chapter 1 femtosecond condensed phase spectroscopy...
TRANSCRIPT
FEMTOSECOND STRUCTURAL DYNAMICS
Chapter 1
Femtosecond Condensed Phase Spectroscopy: Structural Dynamics
NIBBERING
2 NIBBERING
FEMTOSECOND STRUCTURAL DYNAMICS 3
FEMTOSECOND CONDENSED PHASE SPECTROSCOPY: STRUCTURAL DYNAMICS
Erik T. J. Nibbering
Max Born Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany; email:
Key Words femtosecond optical spectroscopy, ultrafast vibrational spectroscopy, pump-probe spectroscopy,
photon echo spectroscopy, ultrafast photochemistry, femtochemistry, dephasing dynamics, spectral
diffusion, solvation dynamics, time-resolved Stokes shift in fluorescence emission, wavepacket dynamics,
vibrational structural marker mode, anharmonic coupling between vibrational modes, intramolecular
vibrational redistribution (IVR), vibrational cooling Based on a contribution published in Encyclopedia of Modern Optics, Volume 5, R. D. Guenther, D. G. Steel
and L. Bayvel, eds., pp. 253-263 (Elsevier, Oxford, 2004).
ULTRAFAST CHEMISTRY
Chemistry means rearrangement of atoms in/between molecules. Chemical bonds are broken and/or formed,
leading to a change in chemical composition from reactants to products during a reaction. Following the
temporal behaviour of the reaction all the way from reactant – via possible intermediates – towards the product
state(s) amounts to deciphering the molecular processes that lead to these chemical reaction dynamics. Molecular
rearrangements from reactant to product may encompass many orders of magnitude in time (see Fig. 1).
Typically the larger and more involved the rearrangements are, the more time it takes for a molecular species to
reach the final state. Rearrangements of biomolecular structure occur in micro- to milliseconds (spontaneous
folding of small proteins consisting of several hundreds of amino acid units),[1, 2] or longer (DNA multiplication,
protein synthesis in ribosomes).[3, 4] In these conformational dynamics hundreds to thousands of chemical bonds
change their nature. Bimolecular reaction dynamics in liquid solution occur on time scales of nanoseconds or
longer, being controlled by the relatively slow diffusional motions of the reaction partners to each other.[5] Many
elementary processes in chemistry, however, occur on much faster time scales.[6-9] In fact, when one considers
the dynamical event of a single bond rearrangement the relocation of the (relatively few) atoms appear to take
place as ultrafast events. Bond fission,[8, 10-12] hydrogen and proton transfer,[13-20] electron transfer,[21-25] and
cis/trans-isomerizations [26-29] have been found to occur on femto- to picosecond time scales (“femtochemistry” [8, 30-34]). The dynamics of these elementary processes are not only determined by the energy landscapes of the
reacting partners. The energy landscapes (potential energy surfaces) are determined by molecular parameters
4 NIBBERING
such as relative orientation (distances, angles) of the reaction partners.[35-37] the energy levels of the reactant,
intermediate and product species, and – very important – the energy barriers represented by transition states.[38-
40] When considering condensed phase reaction dynamics the important role of the surrounding solvent has been
recognized.[41-45] The solvent shells modulate energy levels of the reactant, intermediate and product states
through electrostatic interactions. In the liquid phase the solvent fluctuations lead through these interactions to
fluctuating energy levels of the reaction partners. In addition, the solvent may facilitate chemical reactions
through energy exchange with the reaction partners, leading to efficient dissipation of excess energy, making
chemical reactions often irreversible. The processes that are extremely dominated by these solvent interactions
(such as molecular collisions,[46, 47] electronic [48-54] and vibrational dephasing,[55] and vibrational relaxation [56-59])
are also often found to occur on femto- to picosecond time scales. The outcome of a bond fission may be a null
effect, when the dissociating fragments are forced by the surrounding solvent to recombine and relax (“cage
effect” [60, 61]).
Spectroscopy has been a prime tool to obtain insight into these key molecular processes. Reactant,
intermediate and products contribute to the spectra with their respective molecular resonances. With spectral
domain spectroscopy one may in principle obtain a precise determination of structural information. Fluctuations
of energy levels of these species by the solvent interactions, and finite lifetimes contribute to a broadening of
these molecular resonances.[62-64] Using steady-state spectroscopy one could try to determine these effects
through a lineshape analysis. [65-67] Using this approach, the results have to be analysed with an a priori defined
model representing the dynamics. The disadvantage lies in the averaging over all time scales inherent in spectral
domain spectroscopy, where details of transient states may be lost in this averaging procedure. In contrast, in
experiments designed to grasp the molecular dynamics in real time the temporal resolution is the prerequisite
COLLISION TIME
IN LIQUIDSMOLECULAR ROTATION
SOLVENTRELAXATION
ELECTRONICDEPHASING
VIBRATIONAL DEPHASING
INTRAMOLECULAR VIBRATIONAL
REDISTRIBUTION
VIBRATIONAL MOTIONINTERNAL CONVERSION
INTERSYSTEM CROSSING
PHYSICS
femto nano10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3
pico micro milli
10-15
RADIATIVE DECAY
CHEMISTRYAND BIOLOGY
HYDROGEN AND PROTON TRANSFER
PROTEIN INTERNAL MOTIONS
ELECTRON TRANSFERIN PHOTOSYNTHESIS
TORSIONALDYNAMICS
OF DNA
PHOTODISSOCIATION
PHOTOCHEMICAL ISOMERIZATION
CAGERECOMBINATION
HELIX COIL TRANSITION
PROTEIN FOLDINGTERTIAIRY STRUCTURE
VIBRATIONAL COOLING
ELECTRON TRANSFER
ION PUMPING THROUGH MEMBRANES
ENZYME CATALYSIS
COLLISION TIMEIN LIQUIDS
MOLECULAR ROTATION
SOLVENTRELAXATION
ELECTRONICDEPHASING
VIBRATIONAL DEPHASING
INTRAMOLECULAR VIBRATIONAL
REDISTRIBUTION
VIBRATIONAL MOTIONINTERNAL CONVERSION
INTERSYSTEM CROSSING
PHYSICS
femto nano10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3
pico micro milli
10-15
femto nano10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3
pico micro milli
10-15
RADIATIVE DECAY
CHEMISTRYAND BIOLOGY
HYDROGEN AND PROTON TRANSFER
PROTEIN INTERNAL MOTIONS
ELECTRON TRANSFERIN PHOTOSYNTHESIS
TORSIONALDYNAMICS
OF DNA
PHOTODISSOCIATION
PHOTOCHEMICAL ISOMERIZATION
CAGERECOMBINATION
HELIX COIL TRANSITION
PROTEIN FOLDINGTERTIAIRY STRUCTURE
VIBRATIONAL COOLING
ELECTRON TRANSFER
ION PUMPING THROUGH MEMBRANES
ENZYME CATALYSIS
Figure 1 Chart showing the ultrafast time scales of fundamental physical and chemical processes (inspired by charts
of G. R. Fleming (1986) [6] and A. H. Zewail (2000) [9]).
FEMTOSECOND STRUCTURAL DYNAMICS 5
UV-VISPump
UV/VISProbe
UV/VISProbe
UV/VISProbe
UV-VISPump
UV-VISProbe
UV-VISProbe UV-VIS
Probe
n
n
1
1
0
n
10
n
1
Figure 2 Ultrafast time-resolved electronic spectroscopy. A UV/vis-pump pulse excited an electronic resonance, and
a probe pulse determines, depending on the tuning in the UV/vis population changes in the reactant ground or excited
states or in the product state.
quantity in observation of these processes. In time-resolved experiments one can trigger a chemical reaction at a
well-defined point in time, after which one can follow the conformational changes from reactant – via possible
intermediates – to the product, and identify any possible transition states along the reaction pathways.
During the last century the technological advances in time-resolved spectroscopy have prompted significant
breakthroughs in the study of chemical reaction dynamics. Initially the temporal resolution was given by the
duration of flashes from light bulbs (“flash” spectroscopy) or by rapid mixing of reaction partners (stopped-flow
technique), as developed by Nobel Laureates Eigen, Norrish and Porter,[68] and many others. These techniques
allow a temporal resolution of at best milliseconds. Already up to the early 1960s it was understood that
elementary reaction dynamics occurs on much faster time scales.[69-72] Fourier spectroscopy may improve time
resolution down to microseconds or slightly less. With the advent of pulsed laser sources with ever increasing
temporal resolution, a wide arena of time-resolved spectroscopic techniques has emerged. Nanosecond laser
systems are known since the early 1960s,[73] picosecond pulses can be generated since the 1970s,[74, 75] the first
femtosecond laser system was reported in 1981,[76] and currently laser engineering groups are breaking into the
attosecond domain. [77-79] The majority of pulsed laser systems operates at visible and near-infrared wavelengths.
This means that usually chemical events in ultrafast time-resolved spectroscopy are initiated by electronic
excitation (“photochemistry”). Subsequent molecular rearrangements have then to be followed by probing the
electronic states through electronic resonances (UV/vis-pump – UV/vis-probe or UV/vis four-wave mixing
6 NIBBERING
UV-VISPump
Mid-IRProbe
Mid-IRProbe
Mid-IRProbe
UV-VISPump
Mid-IRProbe
Mid-IRProbe
Mid-IRProbe
n
n
1
1
0
n
10
n
1
Figure 3 Ultrafast time-resolved infrared spectroscopy. A UV/vis-pump pulse excites an electronic resonance, after
which the populations are followed with an IR-probe pulse by inspection of marker modes in the different electronic
states.
spectroscopy) (Fig. 2), or via vibrational resonances (UV/vis-pump – IR/Raman-probe spectroscopy) (see Figs. 3
and 4).
LASER TECHNOLOGY Since the beginning of the 1990s a major advancement in femtosecond laser technology has emerged by the
discovery of Kerr lens mode locking in laser oscillators [80] with Ti:sapphire as lasing material.[81] Ultrastable and
ultrashort laser pulses tunable between 700 and 1000 nm can be generated with durations as short as 5 fs.[82] The
second advancement is due to the ability of Ti:sapphire as laser amplifying material using the method of chirped
pulse amplification.[83-86] Pulses with output powers up to several W with repetition rates in the kHz-regime are
now routinely generated.[87-91] These developments facilitate the efficient generation of ultrashort pulses tunable
from the UV/vis [92-101] to the mid-infrared [102, 103] and even beyond to the THz-regime [104] using schemes based
on nonlinear optics. Frequency conversion of the fundamental output of an amplified Ti:sapphire laser system is
then achieved with nonlinear processes [105] such as self-phase modulation and supercontinuum generation, nth-
order harmonic generation (n = 2,3,4..), sum and difference frequency generation, or parametric generation and
amplification. As a result one can now almost arbitrarily tune the excitation and probe wavelengths of the
applied laser pulses. Additional parameters that one may alter are pulse duration (from less than 10 fs up to
several ps) and pulse energy (in the mJ-range or less; typically one uses for condensed phase spectroscopy pulse
FEMTOSECOND STRUCTURAL DYNAMICS 7
UV-VISPump
RamanProbe
RamanProbe
RamanProbe
UV-VISPump
RamanProbe
RamanProbe Raman
Probe
n
n
1
1
0
n
10
n
1
Figure 4 Ultrafast time-resolved Raman spectroscopy. A UV/vis-pump pulse excites an electronic resonance, after
which the populations are followed with (resonance) Raman-probe pulse by inspection of marker modes in the different
electronic states.
energies in the range of nJ to µJ). More advanced pulse manipulation schemes use amplitude and phase
masks.[106] The latter aspect holds the promise of amplitude and phase control of molecular excitation, feeding
the ultrafast chemist’s dream of laser control of molecular reaction dynamics.[107-112]
ULTRAFAST ELECTRONIC SPECTROSCOPIC TECHNIQUES Pulsed laser sources enable a variety of experimental approaches to determine transient states. Already since the
development of nanosecond laser sources time-resolved pump-probe and four-wave mixing spectroscopy have
been widely used. In a first approach often one uses these forms of spectroscopy to probe in real time
populations of reactant, transient and product states as function of pulse delay.[6] With the advent of pico- and
femtosecond laser sources the dynamics of coherence properties of the material response [53, 54, 113-115] have been
investigated as well.
The following techniques have been widely used in ultrafast electronic condensed phase spectroscopy
a) UV/VIS-PUMP – UV/VIS-PROBE SPECTROSCOPY
In this technique a “pump” pulse resonant to a transition promotes the molecules to an electronic excited state,
and the time-dependent populations are determined by measurement of the transmission of a time-delayed
“probe” pulse (Fig. 5). The absorbance change ∆A(τ) = -10log[T(τ)/T(τ =0)] (with T for transmission change and
8 NIBBERING
DetectorSample
Eprobe
Epump
Eprobe
P(3)τ
Sample
Eprobe
P(3)
Monochromatorand Detector
Eprobe
Epump
τ
(a)
(b)
DetectorSample
Eprobe
Epump
Eprobe
P(3)τ
Sample
Eprobe
P(3)
Monochromatorand Detector
Eprobe
Epump
τ
(a)
(b)
Figure 5 Pump-probe technique: A pump pulse induces an absorbance change in a sample, that is subsequently
measured by a time delayed probe pulse, either spectrally integrated (a) or spectrally resolved (b).
τ the pulse delay) is a direct indication of populations of states. Here one can tune the probe pulse to the same
transition as the pump pulse, and one measures an absorbance decrease due to a bleach of ground state
population (i.e. fraction of molecules being excited), and due to molecules in the excited state stimulated back to
the ground state. One could also tune the probe pulse to transitions between the transient state and higher lying
states. For electronic spectroscopy often transitions between the ground and first excited state (S0 → S1) overlap
with excited state absorptions (S1 → Sn). One has to rely then on numerical analysis procedures [116] such as
singular value decomposition and decay associated spectra, that correlate spectral features with temporal
behaviour.
The time resolution of the experiment is given by the cross-correlation between pump and probe pulses. In
the case of extremely short pulses one has to consider the effects of group velocity dispersion between different
frequency components due to different travel times through the samples, leading to pulse temporal broadening.
For the case of pump and probe tuned to different wavelengths the time-resolution is usually dominated by group
velocity mismatch between pump and probe pulses.
When ultrashort laser pulses are used, often the applied spectral bandwidth enables simultaneous excitation
of several vibrational sub-levels in vibronic transitions. Due to the phase-relationship of the applied laser pulses
these vibrational sub-levels are prepared in states that are well-defined in temporal phase with respect to each
other. Such a coherent superposition of vibrational eigenstates is nothing less than a vibrational wavepacket, that
will evolve in time. The occurrence of vibrational wavepacket motions leads to oscillatory modulations of the
pump-probe signals.
b) TIME-RESOLVED FLUORESCENCE SPECTROSCOPY
Here again a “pump” pulse excites an electronic resonance. The transient excited states are now probed through
their spontaneous fluorescence emission, either by use of time-correlated single photon counting or by
fluorescence upconversion with a gating pulse in a nonlinear medium (Fig. 6). Single-photon counting has a time
resolution of at best a few picoseconds. Fluorescence upconversion can be performed with a time resolution of
100 – 200 fs. The advantage lies in the fact that the measured signals are more likely due to the specific excited
states only, and not corrupted by other contributions.
FEMTOSECOND STRUCTURAL DYNAMICS 9
Sample
Epump
Single Photon Counter
CollimatingLens
(a)
(b)
Detector
SampleEpump
UpconversionCrystal
Esum
P(2)
Egate
τ
CollimatingLens
Sample
Epump
Single Photon Counter
CollimatingLens
Sample
Epump
Single Photon Counter
CollimatingLens
(a)
(b)
Detector
SampleEpump
UpconversionCrystal
Esum
P(2)
Egate
τ
CollimatingLens
Detector
SampleEpump
UpconversionCrystal
Esum
P(2)
Egate
τ
CollimatingLens
Figure 6 Time-resolved emission detection: The fluorescence emission is either temporally resolved by time-
correlated single photon counting (a) or by up-conversion with a gating pulse (b).
c) ELECTRONIC FOUR WAVE MIXING SPECTROSCOPY
In time-resolved degenerate electronic four-wave mixing spectroscopy, where all the three applied laser pulses
(with wavevectors k1, k2 and k3) are tuned to the same electronic resonance, one can detect a nonlinear signal in
the phase-matched direction kS = k3 + k2 – k1 (Fig. 7). The first laser pulse generates a coherent superposition
between the electronic ground and excited states. This electronic coherence evolves in time during the period
(denoted as coherence time τ), until the second pulse converts this coherence in a population frequency grating
in the electronic ground and excited states.[113] After a second time period of free evolution (denoted as
population or waiting time T), this frequency grating is again transformed into an electronic coherence, which
after some time evolution generates a macroscopic polarization in the phase-matched directions. This
macroscopic polarization is either directly measured by a time-integrating detector (in which case one measures
the intensity signal proportional to the absolute square of the nonlinear polarization), or one uses another light
pulse that mixes as local oscillator with the nonlinear polarization (and the signal is proportional to the amplitude
of the polarization). The time resolution is determined by the third-order autocorrelation of the applied pulses.
10 NIBBERING
Sample
k2
k1P(3)
k3 + k2 - k1
Detector
k3
τΤ
Sample
k2
k1 P(3)
k3 + k2 - k1 Detector
k3
ELO
τΤ
(a)
(b)
Sample
k2
k1P(3)
k3 + k2 - k1
Detector
k3
τΤ
Sample
k2
k1P(3)
k3 + k2 - k1
Detector
k3
τΤ
Sample
k2
k1 P(3)
k3 + k2 - k1 Detector
k3
ELO
τΤ
Sample
k2
k1 P(3)
k3 + k2 - k1 Detector
k3
ELO
τΤ
(a)
(b)
Figure 7 Beam geometry for time-resolved four-wave mixing (grating/photon echo) spectroscopy: The nonlinear
signal is transmitted by the sample in a phase-matched direction and its intensity signal (a) or its amplitude by
interference with a local oscillator field (b) is detected by a time-integrating detector.
Depending on the delay between the three input pulses, and which delay one varies, different dynamics can
be measured.[64, 113, 117] When one performs an experiment with τ scanned and T set at zero, one measures the
electronic coherence decay (due to electronic dephasing) time in a two-pulse photon echo experiment. When on
the other hand τ is set to zero, and T is scanned, one measures the evolution of a population grating, and
electronic lifetimes can be deduced. In a three pulse photon echo experiment both pulse delays are scanned, and
the signals give insight into both electronic coherence and frequency grating decay (due to electronic dephasing
and spectral diffusion respectively). A novel extension of four-wave mixing technique is the three pulse echo
peak shift (3PEPS).[118-120] In a 3PEPS measurement the delay time τmax is determined, where the echo signal has
a maximum along the coherence delay τ, as a function of the population delay T. This method provides direct
insight into the frequency fluctuation correlation function that governs the linear and nonlinear signals.
Extension of the method to multi-colour four-wave mixing spectroscopy [121, 122] has been demonstrated.
Photon echo spectroscopy of electronic transitions has until now been performed using homodyne detection
geometries, where the photon echo intensity signal is measured by a time-integrating detector (Fig. 7(a)). A
recent development in phase-stable heterodyne detection schemes involving an additional local oscillator pulse
(fig. 7(b)), enables measurement of the complex amplitude of the photon echo signal.[123-125] This advancement
has set the route for multi-dimensional spectroscopy, correlating coherences between coupled two level systems.
FEMTOSECOND STRUCTURAL DYNAMICS 11
ELECTRONIC CONDENSED PHASE SPECTROSCOPY:
FEMTOCHEMISTRY AND SOLVATION DYNAMICS In the narrow sense of meaning “femtochemistry” deals with the real-time observation of nuclear motions during
chemical reactions. Quantum mechanics teaches us that this is only possible when molecular systems are
prepared in vibrational superpositions.[126] Only in the case of quantum states describing vibrational wavepackets
evolving in time the narrow-defined positions of nuclei allow for a real-time description of molecular
rearrangements, or in other words: dynamics. This has been demonstrated in the gas-phase in landmark
experiments [8] by Nobel Laureate Zewail [68] (Fig. 8).
In the condensed phase at room temperature, however, often such well-defined quantum states are harder to
prepare, since the ensembles of molecular systems exist in mixed states. Coherent laser excitation on an
ensemble will then prepare mixed states as well, and then information that one obtains from the experiments is
less explicit. In addition, room temperature liquid solutions induce extremely fast fluctuations in the states of the
molecules under study and as a consequence the electronic and vibrational coherences show ultrafast decaying
behaviour. This limits the temporal window with which one can follow the evolution of vibrational
wavepackets.[127]
Most of the ultrafast spectroscopic experimental work performed on photochemistry in the condensed phase,
being described as “femtochemistry”, only deals with the time scales of changes in electronic states (usually
indicated with reaction rates typefied with exponentially decaying or rising functions). In this regard it is better
to speak of “kinetics” rather than “dynamics”, although both terms are used in condensed phase spectroscopy.
Due to the relative broad electronic spectra of condensed phase molecules masking any structural detail, it is
hard to derive nuclear motions in real time, and as such it is difficult to make any statements about dynamics of
molecular structures during chemical reactions.
1
0
nuclear coordinate Q
v=0v=1
v=2
v=0v=1
v=21
0
nuclear coordinate Q
v=0v=1
v=2
bound potential
dissociative potential
Figure 8 Ultrafast excitation with broadband pulses creates coherent superpositions of vibrational eigenstates, i.e.
vibrational wavepackets. These wavepackets are generated in electronic excited and ground states (a), and their time-
dependence can be determined in pump-probe and four-wave mixing experiments. When level crossing occurs to
another electronic state, the vibrational wavepacket may be observed to evolve along the reaction coordinate (b).
12 NIBBERING
Electronic resonances have also been used to probe the dynamical interactions between a non-reactive solute
and the surrounding fluctuating solvent.[21, 49-54, 128] The idea behind these experiments is to achieve information
about the time scales of solvent fluctuations on (and solvent motions due to a change in) the electronic charge
distribution in a molecule (as induced by an electronic excitation). Usually the solvent motions are characterized
with a frequency fluctuation correlation function (Fig. 9). This information is highly relevant for the case of
reacting molecules, where electronic motions accompany the relocations of nuclei, even in electron transfer
reactions, where the nucleic rearrangements are modest. Solvent motions have been shown to often control
reaction rates. Solvent rearrangement as a response to a change in electronic charge distribution is known as
solvation dynamics. Experimental probes for solvent motional fluctuations are electronic coherence decay
(electronic dephasing) and population frequency grating decay (spectral diffusion) that can be measured in two
and three pulse photon echoes.[48-51, 53, 54] Solvent adaptation to new charge distributions can be followed with the
time-dependent Stokes-shift in fluorescence emission,[21, 52, 128] as well as in three pulse photon echoes [49, 53, 54]
(in so-called three pulse echo peak shift measurements). Ultimately these experiments resolve the temporal
characteristics of the frequency fluctuation correlation function. Multi-dimensional photon echo spectroscopy
does not only provide insight into the dephasing and spectral diffusion of electronic transitions, but also has the
potential to reveal the couplings between chromophores.[129-131] This information is important in the context of
transfer of electronic excitation in pigments, in particular light harvesting complexes.[23, 132, 133]
0.0
0.2
0.4
0.6
0.8
1.0
E2E1* E3
τ ΤEcho
E2E1* E3
τ ΤEcho
E2E1* E3
τ Τ
EchoE2E1* E3
τ Τ
Echo
C(t)
Time t
Popu
latio
n gr
atin
g
Frequency
Popu
latio
n gr
atin
g
Frequency
Popu
latio
n gr
atin
g
Frequency
Popu
latio
n gr
atin
g
Frequency
Figure 9 Solute-solvent interactions as characterized by the transition frequency fluctuation correlation function C(t)
= <δω(t)δω(t=0)>, with δω(t) the fluctuating part of the transition frequency. This quantity can be measured in photon
echo and time-resolved fluorescence experiments. In a three pulse photon echo experiment phase information as given
by the excited state frequency grating created with the first two interactions, is washed out due to solvent fluctuations
and Stokes-shifts to lower frequencies due to solvent rearrangement. A similar plot can be drawn for the ground state
frequency grating. (Figure adapted from Ref. [54]).
FEMTOSECOND STRUCTURAL DYNAMICS 13
ULTRAFAST VIBRATIONAL SPECTROSCOPY IN PHOTOCHEMISTRY: STRUCTURAL DYNAMICS Vibrational spectroscopy has despite a smaller signal sensitivity due to smaller transition cross sections several
advantages over electronic spectroscopy. Vibrational transitions have typically smaller bandwidths than
electronic transitions due to longer dephasing times (the exception to the rule: O-H/O-D stretching bands of
hydrogen bonded hydroxyl groups). Specific signal contributions are thus easier tractable in vibrational
spectroscopy than in electronic spectroscopy. Vibrational bands can often be correlated to specific vibrational
motions by inspection of the transition frequencies, (e.g. O-H, N-H, and C-H stretching bands can be found in
the 3000 cm-1 range, C=O and C=N stretching modes are located near 1600-1750 cm-1, O-H, N-H and C-H
bending vibrations between 1500-1650 cm-1, C-O stretching mode around 1200-1300 cm-1 etc.), and in particular
the frequency range between 1000 and 1800 cm-1 is called the fingerprint region because of this reason.
Measurement of vibrational bands thus leads to identification of particular vibrational motions, and conclusions
can be drawn on specific structural motifs in the molecules. Vibrational bands can be infrared (IR) or Raman
active (sometimes: both), and both IR and Raman techniques have been widely applied in structural
determination studies ranging from small molecules to larger biomolecular systems. In ultrafast photochemistry
one thus excites the molecules with a UV/vis-pump pulse, and an IR/Raman-probe pulse follows the outcome of
the chemical reaction by inspection of vibrational bands of reactant, transients and products.
Vibrational spectroscopy has the potential of revealing site-specific information if the marker modes are due
to nuclear motions of specific molecular side-groups.[134-138] For instance, hydrogen bonding induces marked
shifts of O-H, N-H, C=O and C=N bands.[139, 140] Observation of changes in spectral shifts reveal important
information on hydrogen bond interactions (weakening/strengthening or even hydrogen bond cleavage).[134-136,
141, 142] Infrared spectroscopy is able to probe small molecular species in solution that typically have their
electronic resonances in the far-UV (making electronic spectroscopy impossible, since normally the solvent
would absorb this radiation) (Fig. 10). For instance, in acid-base neutralization reactions,[143, 144] where the
acidity of a so-called photoacid is switched on by use of a UV pulse, a vis probe pulse would only be able to
probe the photoacid (or its conjugate photobase), thus revealing only when a proton leaves the photoacid. An
infrared pulse can, besides probing vibrational resonances of the photoacid, also probe bands of a small base (or
its conjugated acid) indicating when a proton arrives at the base.
In the case that the vibrational normal modes do not allow such a structural insight into site-specific groups,
one can make a comparison of the experimentally observed vibrational bands with predictions made by quantum
chemical calculations.[145-147] When a full correspondence between experiment and theory is possible, one can
make statements about the three-dimensional structure. With current quantum chemical calculational routines
such as density functional theory, medium-sized molecules are routinely calculated for electronic ground state
conformations. Reliable results of transient and product states in electronic excited states can be obtained with
the routine ab initio complete active space self-consistent field (CASSCF),[148] albeit for mid-size molecules of at
most on the order of about 20 atoms. New developments in numerical procedures, such as time-dependent
density functional theory (TD-DFT) [149] may prove fruitful in the calculation of larger molecular systems in
electronic excited states.
14 NIBBERING
-O3S
SO3--O3S
O--O3S
SO3--O3S
O
H
-O3S
SO3--O3S
O
HD-O3S
SO3--O3S
O-
250 psdeuteron transfer to solvent water + +D O2
+D O3
D
~ 10-100 ps
CCH
O
O 3
_ CCH
O
OD 3
deuteron scavenging by acetate + +
CCH
O
O 3
_
CCH
O
OD 3
indirect deuteron transfer to
acetate
+~ 200-500 ps
-O3S
SO3--O3S
O--O3S
SO3--O3S
O
H
-O3S
SO3--O3S
O
HD-O3S
SO3--O3S
O
HD-O3S
SO3--O3S
O-
250 psdeuteron transfer to solvent water + +D O2
+D O3
D
~ 10-100 ps
CCH
O
O 3
_ CCH
O
OD 3
deuteron scavenging by acetate + +
CCH
O
O 3
_
CCH
O
OD 3
indirect deuteron transfer to
acetate
+~ 200-500 ps
Figure 10 In excited state acid-base neutralization experiments the proton dissociation can be followed on two sides
with ultrafast infrared spectroscopy. Vibrational marker modes of photoacid and conjugated photobase indicate when
the proton leaves the acid. The marker mode of acid formed by proton pick-up by the accepting base is a direct measure
of the arrival time of the proton at the base. Depending on relative concentrations either the indirect proton transfer via
the solvent or direct scavenging of the proton by the base dominates the dynamics. (Adapted from Refs. [143, 144]), where
the experiment was performed on photoacid-base pairs in deuterated water).
During the last years femtosecond IR spectroscopy has been used in photoinduced chemical reactions
ranging from hydrogen bond rearrangements,[134-136, 141, 142] excited state hydrogen [137, 138] and proton transfer,[143,
144, 150] transformations of photochromic switches,[151-154] excited state charge transfer,[145-147, 155, 156] bond fission [12, 157-163] and cis-trans isomerizations.[164-167] Here an ultrashort UV/vis “pump” pulse promotes the molecule to
an electronic excited state, and the reaction is followed by a measurement of the absorbance change of a “probe”
pulse tuned in the mid-IR region where the vibrational marker modes sensitive to structural changes have their
resonances. Experimentally one performs spectrally-resolved transient IR spectroscopy. Femtosecond IR
parametric devices deliver pulses with bandwidths of 150 cm-1 or more. In order to be able to observe shifts as
small as the linewidths of IR-active vibrations, one usually measures the IR absorbance change with a detector
after spectral dispersion with a monochromator. As a side-effect of this spectral dispersion ground-state bleach
signals often appear to grow in at negative pulse delay with the dephasing time of the transition.[168, 169] This
effect, known as “perturbed free induction decay” is a common feature of spectrally-resolved nonlinear pump-
probe spectroscopy of bleached transitions with dephasing times much longer than the time resolution of the
experiment. The time resolution of the experiment is given by the cross-correlation between the UV/vis-pump
and IR-probe pulse (about 100-200 fs), and is typically dominated by group velocity mismatch in samples with
thicknesses of about 100 µm.
In principle the same approach can be followed by probing Raman-active vibrations.[170, 171] In this case the
spectral resolution is not only determined by the monochromator through which the spontaneous Raman
emission is dispersed, but also by the bandwidth of the gating pulse by which the Raman effect is induced. As a
result UV/vis-pump – Raman-probe spectroscopy has a temporal resolution of around 1 ps (a compromise
between spectral and time resolution). Due to the even weaker cross sections of Raman transitions one often uses
resonance enhancement by tuning the gating pulse close to or resonant with an electronic transition of the state
that is probed. The advantage is that one usually only observes Raman bands of the state under inspection. The
FEMTOSECOND STRUCTURAL DYNAMICS 15
drawback is that fluorescence resulting from the resonant electronic excitation often inhibits detection of Raman
bands in extended spectral ranges. Unwanted fluorescence can be suppressed by gating the Raman signal,
rejecting the fluorescence emitted on longer time scales,[172] or can be circumvented by applying coherent
vibrational spectroscopic techniques, e.g. coherent anti-Stokes Raman scattering (CARS).[173-175]
Raman spectroscopy offers an additional insight into how chemical reactions evolve. By comparison of the
intensities of anti-Stokes and Stokes lines of a particular vibration, it is possible to derive time-dependent
changes in the excitation level of this vibration.[176-179] One can draw conclusions on whether particular modes
initially drive a chemical reaction (“state transition promoting modes”), or only get excited after the transition is
made, by taking up the excess energy released by the reaction (“accepting modes”). In such a way insight is
obtained on the energy flow inside a molecular system (intramolecular vibrational redistribution, abbreviated as
IVR) and vibrational energy dissipation to the surrounding solvent (vibrational cooling). Infrared spectroscopy is
less powerful in revealing this, since red-shifted transient absorption of vibrational bands may either mean that
the particular mode is highly excited (the red-shift is a consequence of the diagonal anharmonicity of the
vibration), or it may mean that other modes are highly excited and these cause a red-shift of the marker mode
under inspection (the red-shift is then due to off-diagonal anharmonic coupling with other modes).
EQUILIBRIUM STRUCTURAL DYNAMICS IN THE ELECTRONIC GROUND STATE Existence of anharmonic coupling between vibrational modes means that the vibrational motions are not
decoupled from each other. These couplings always exist, since otherwise no IVR and vibrational cooling [57, 58]
(no relaxation) would occur. When the couplings are significantly large, excitation of one specific mode will
induce a significant instantaneous shift of other vibrations anharmonically coupled to this particular mode.
Estimation of the magnitude of these couplings should lead to a determination of the curvatures of potential
energy surfaces along the respective coordinates. With current state-of-the-art femtosecond infrared technology
(with time resolution of about 150 fs or less) it is possible to excite infrared-active vibrations and to probe the
same or other vibrations (either in the IR or by the Raman process), enabling insight into the anharmonic
couplings between these vibrational modes.[180]
Direct anharmonic couplings are probed in IR-pump – IR-probe and IR photon echo spectroscopy (Fig.
11).[55, 181] In the case of peptides the excitonic (Davydov) couplings between amide I vibrations of the amino
acid units have been the subject of extensive study since these lead to spatial information of the relative
orientations of the different amide I modes, and – thus – of the spatial orientation of the amino acid units inside
the peptide.[182, 183] Exploring the effects of the delay between the IR pulses on the observed signals give insight
into the fluctuations of these orientational features, or in other words: into structural dynamics of peptides.[184, 185]
In the case of hydrogen bonded O-H/O-D stretching vibrations the anharmonic couplings with underdamped
low-frequency modes modulating the hydrogen bond distance lead to marked modulations of observed pump-
probe [186-190] and echo signals [189, 191, 192] as function of pulse delay. These experiments reveal which modes
couple strongly to the hydrogen stretching oscillator.
Fluctuations in couplings between vibrational modes (in particular with those of the solvent) induce
dephasing of the vibrational coherences.[181, 193-195] The dephasing and spectral diffusion dynamics of vibrational
transitions, e.g. the O-H stretch vibration of HOD dissolved in D2O,[196-201] or the O-D stretch of HOD in
H2O,[202] have been determined by IR photon echo spectroscopy. From these studies the time scales of structural
memory decay of hydrogen bond networks can be derived.[55, 59, 203, 204] As opposed to isotopically diluted
16 NIBBERING
q
nuclear coordinate Q
v = 0
q
Qv = 1Q
v = 2Q
v = 0Qv = 1Q
v = 2Q
Q(t)
q(t)
Q(t)
q(t)
q(t) O-H stretching vibrationhigh frequency ~ 3000 cm-1
period ~10 fsdephasing ~ 100 fs
Q(t) O....O H-bond vibrationlow frequency ~ 50-350 cm-1
period ~ 100-500 fsdephasing ~ 1 ps
anharmonic coupling
q(t) O-H stretching vibrationhigh frequency ~ 3000 cm-1
period ~10 fsdephasing ~ 100 fs
Q(t) O....O H-bond vibrationlow frequency ~ 50-350 cm-1
period ~ 100-500 fsdephasing ~ 1 ps
anharmonic coupling
Figure 11 In hydrogen-bonded hydroxyl groups a strong anharmonic coupling exists between the hydroxyl stretching
and modes modulating the hydrogen-bond distance. A Born-Oppenheimer like separation of time scales of vibrational
motion between the high-frequency O-H/O-D stretching and the low-frequency hydrogen bond modes enables a
description with potential energy surfaces for the low-frequency mode as function the quantum state of the hydroxyl
stretching vibration. The formation of low-frequency vibrational wavepackets in ultrafast IR spectroscopy of O-H/O-D
stretching modes is then fully analogous to wavepacket formation in ultrafast electronic spectroscopy.
O- H/O-D stretching oscillators (HOD in D2O or HOD in H2O), the vibrational dynamics in neat liquid H2O
appears to be much faster. An accurate determination of the population relaxation, anisotropy decay, vibrational
dephasing and spectral diffusion has recently been performed in two-dimensional heterodyne detected photon
echo experiments.[205] In neat H2O the couplings of the O-H stretching and bending [206] oscillators with
librational modes (hindered rotations of the hydrogen bond network) have been assigned as the reason for these
ultrafast dynamics.
Couplings between vibrational modes ultimately lead to population relaxation through intramolecular
vibrational redistribution effects and vibrational cooling. Ultrafast two-colour IR-pump – IR-probe reveals
whether excitation of one IR-active vibration is followed by population transfer into another IR-active mode.[207,
208] With IR-pump – Raman-probe one can estimate whether Raman-active vibrations are transiently excited.[209]
In the case of hydrogen-bonded O-H/O-D stretching bands an extremely short population relaxation time T1
(below 1 ps) is observed, as well as an ultrarapid dephasing time T2 (200 fs or less).[55] These values are
definitely longer for other vibrations, from which it has been concluded that the strong anharmonicities [210, 211]
in hydrogen-bonded vibrational systems enable dephasing [198] and relaxation processes [212-214] to have such a
rapid impact.
FEMTOSECOND STRUCTURAL DYNAMICS 17
FUTURE DEVELOPMENTS Future activities in the determination of dynamically evolving molecular structures in the condensed phase may
involve the aforementioned application of amplitude and phase controlled excitation pulses in optimal control of
chemical reactions.[215] Vibrational spectroscopy may be used as a tool in determination of evolving structures
after electronic excitation by a shaped pulse tuned in the UV/vis. Infrared pulses could also be shaped in
amplitude and phase,[216] and may be used in the exploration of steering of chemical reactions in the electronic
ground state. Multi-dimensional vibrational spectroscopy is an object of extensive research.[129, 130, 217, 218]
Extension of the method to determination of structure of transient states [155, 165] will be lead to new results on
molecular rearrangements, e.g. polypeptides reaching a new equilibrium after inducing a UV-excitation induced
geometric change of a photochromic switch incorporated in the peptide structure. Much activity is currently also
put in the development of ultrafast structure resolving techniques such as electron diffraction,[219-223] X-ray
diffraction [160, 224-231] and X-ray spectroscopy.[232] While still extremely demanding at a technological level,
definitive implementation of these structure resolving techniques will open up new areas of ultrafast chemical
dynamics.
OUTLINE OF THE HABILITATION THESIS In this Habilitation Thesis a review of ultrafast vibrational spectroscopy of the hydrogen stretching oscillator as a
probe for structural dynamics of hydrogen bond equilibrium dynamics is presented in Chapter 2 (see Fig 12).
Our results, obtained with a research effort embedded within the collaborative research centre Analysis and
Control of Ultrafast Photoinduced Reactions (SFB 450) are summarized together with those of other groups
worldwide active in the research field of ultrafast hydrogen bond dynamics. In Chapter 3 a review is given on
recent efforts of ultrafast vibrational spectroscopy on elementary chemical transformations, ranging from excited
state intramolecular hydrogen transfer, intermolecular proton transfer in bimolecular acid-base neutralization
reactions, hydrogen bond dynamics in solvation dynamics studies, charge transfer, bond fission, cis/trans
isomerizations and more elaborate rearrangements. The most notable research efforts on these – more or less in
chronological order – from the Max Born Institut are collected in detailed reports in the following chapters.
Hydrogen bond and solvation dynamics of a coumarin laser dye is discussed in Chapter 4. Here an optical
excitation of the coumarin chromophore induces breaking of the hydrogen bond with hydrogen bond donors, and
rearrangements of the solvation shells. In Chapter 5 excited state intramolecular hydrogen transfer is studied in
2-(2’-hydroxyphenyl)benzothiazole. In this case the hydrogen transfer is induced along an existing
intramolecular reaction coordinate. Bimolecular proton transfer in photoacid-base pairs including a study of the
excited state characteristics of the photoacid pyranine is treated in Chapter 6, where the solution phase proton
transfer reaction dynamics is intertwined with diffusional motions of the reactants towards each other. The
competition between internal conversion and photoinduced conversion in the photochromic switch pair
spiropyran–merocyanine is discussed in Chapter 7. Finally Chapter 8 reports on polarization-sensitive infrared
spectroscopy of model compounds for photosensor proteins as well as of photoactive yellow protein describe
how structural information on cis/trans isomerization in transient states can be extracted.
18 NIBBERING
Hydrogen bond dynamics in the condensed phase
Structure: - hydrogen bond network - anharmonic coupling between vibrational modes Dynamics: - coherent hydrogen bond wave packet motion - hydrogen bond fluctuation - intramolecular vibrational redistribution - vibrational energy dissipation
Ultrafast chemistry: probing through vibrations
CO
HO
electronic spectroscopy vibrational spectroscopy Physics: - electronic state coupling - vibrational energy redistribution and dissipation Chemistry: - excited state intramolecular hydrogen transfer - bimolecular proton transfer - electron transfer - hydrogen bond rearrangements - bond fission - cis-trans isomerizations
Figure 12(a) Overview of the Habilitation Thesis: hydrogen bond dynamics in the electronic ground state (Chapter
2), and general overview of determination of ultrafast chemistry through probing of vibrations (Chapter 3).
FEMTOSECOND STRUCTURAL DYNAMICS 19
Solute-solvent hydrogen bond dynamics
coumarin 102
hydrogen bond cleavage +
phenol dimer rearrangement
H
H HH
phenoldimercoumarin 102
hydrogen bond cleavage +
phenol dimer rearrangement
H
H HH
phenoldimer
Structure: - site-specific hydrogen bond interaction - solute-solvent coupling Dynamics: - hydrogen bond rearrangement - solvation dynamics
Excited-state intramolecular hydrogen transfer
HN
S
O
HBT-enol
HN
S
O
HBT-enol
hydrogentransfer
hydrogentransfer
HBT-keto
OHN
S
Structure: - electronic state coupling - hydrogen bond reaction coordinate - anharmonic coupling between vibrational modes Dynamics: - intramolecular hydrogen transfer - intramolecular vibrational redistribution - vibrational energy dissipation
Figure 12(b) Overview of the Habilitation Thesis: hydrogen bond dynamics after electronic excitation of a laser dye
(Chapter 4), and excited state intramolecular hydrogen transfer (Chapter 5).
20 NIBBERING
Bimolecular proton transfer in aqueous solution
-O3S
SO3--O3S
O
HD
pyraninephotoacid
-O3S
SO3--O3S
O
HD-O3S
SO3--O3S
O
HD
pyraninephotoacid
CCH
O
O 3
_
acetate
CCH
O
O 3
_
acetate
-O3S
SO3--O3S
O-
pyraninephotobase
-O3S
SO3--O3S
O-
pyraninephotobase
CCH
O
OD 3
acetic acid
CCH
O
OD 3
acetic acid
++bimolecular
deuterontransfer
bimoleculardeuterontransfer
Structure: - acid-base complexation - hydrogen bond reaction coordinate - involvement of water bridges - solvent stabilisation of charge separated states Dynamics: - diffusion - on-contact reaction dynamics - von Grotthuss proton transmission
Photophysics of photochromic spiropyrans
ONCH3
CH3 CH3
NO2NCH3
CH3 CH3
O
NO2
δ−
δ+
spiropyranmerocyanine
ring opening +
cis-trans isomerization
ONCH3
CH3 CH3
NO2ONCH3
CH3 CH3
NO2NCH3
CH3 CH3
O
NO2
δ−
δ+NCH3
CH3 CH3
O
NO2
δ−
δ+
spiropyranmerocyanine
ring opening +
cis-trans isomerization
Structure: - electronic state coupling - large displacement of vibrational modes - anharmonic coupling between vibrational modes Dynamics: - internal conversion - intramolecular vibrational redistribution - vibrational energy dissipation - ring-opening - cis-trans isomerisation
Figure 12(c) Overview of the Habilitation Thesis: bimolecular proton transfer in aqueous solution (Chapter 6) and
photophysics of photochromic spiropyran-merocyanine (Chapter 7).
FEMTOSECOND STRUCTURAL DYNAMICS 21
Photosensor protein chromophore dynamics
HO
NN
CH3
O
CH3HO
N
N
O CH3
CH3
excited statetwist
E-HBDIZ-HBDI
HO
NN
CH3
O
CH3HO
N
N
O CH3
CH3
HON
N
O CH3
CH3
excited statetwist
excited statetwist
E-HBDIZ-HBDI
Structure: - chromophore-solvent or chromophore-protein interaction - site-specific hydrogen bond interaction - single twist vs. hula twist coordinate - electronic state coupling - anharmonic coupling between vibrational modes Dynamics: - hydrogen bond rearrangement - internal conversion - cis-trans isomerisation - intramolecular vibrational redistribution - vibrational energy dissipation - solvent or protein rearrangement
Figure 12(d) Overview of the Habilitation Thesis: photosensor protein chromophore dynamics (Chapter 8).
22 NIBBERING
REFERENCES
[1] M. Gruebele, J. Sabelko, R. Ballew, J. Ervin, Acc. Chem. Res. 1998, 31, 699-707.
[2] A. Troullier, D. Reinstadler, Y. Dupont, D. Naumann, V. Forge, Nat. Struct. Biol. 2000, 7, 78-86.
[3] A. Fersht, Structure and Mechanism in Protein Science: A Guide to Enzyme Catalysis and Protein
Folding, 2 ed., W. H. Freeman and Company, New York, 1999.
[4] B. Nölting, Protein Folding Kinetics, Springer, Berlin, 1999.
[5] S. A. Rice, Diffusion-Limited Reactions, [Comprehensive Chemical Kinetics,Vol. 25], Elsevier,
Amsterdam, 1985.
[6] G. R. Fleming, Chemical Applications of Ultrafast Spectroscopy, [The International Series of
Monographs on Chemistry,Vol. 13], Oxford University Press, Oxford, 1986.
[7] W. Kaiser (Ed.), Ultrashort Laser Pulses and Applications, [Topics in Applied Physics,Vol. 60], Springer,
Berlin, 1988.
[8] A. H. Zewail, Science 1988, 242, 1645-1653.
[9] A. H. Zewail, J. Phys. Chem. A 2000, 104, 5660 -5694.
[10] M. Dantus, M. J. Rosser, A. H. Zewail, J. Chem. Phys. 1988, 89, 6128-6140.
[11] M. Dantus, R. M. Bowman, A. H. Zewail, Nature 1990, 343, 737-789.
[12] M. Lim, T. A. Jackson, P. A. Anfinrud, Science 1995, 269, 962-966.
[13] P. F. Barbara, L. E. Brus, P. M. Rentzepis, J. Am. Chem. Soc. 1980, 102, 5631-5635.
[14] T. Elsaesser, W. Kaiser, Chem. Phys. Lett. 1986, 128, 231-237.
[15] F. Laermer, T. Elsaesser, W. Kaiser, Chem. Phys. Lett. 1988, 148, 119-124.
[16] A. Douhal, S. K. Kim, A. H. Zewail, Nature 1995, 378, 260-263.
[17] A. Douhal, F. Lahmani, A. H. Zewail, Chem. Phys. 1996, 207, 477-498.
[18] T. Elsaesser, in Ultrafast hydrogen bonding dynamics and proton transfer processes in the condensed
phase, Vol. 23 (Eds.: T. Elsaesser, H. J. Bakker), Kluwer Academic Publishers, Dordrecht, 2002, pp. 119-
153.
[19] E. Pines, D. Pines, in Ultrafast hydrogen bonding dynamics and proton transfer processes in the
condensed phase, Vol. 23 (Eds.: T. Elsaesser, H. J. Bakker), Kluwer Academic Publishers, Dordrecht,
2002, pp. 155-184.
[20] T. Schultz, E. Samoylova, W. Radloff, I. V. Hertel, A. L. Sobolewski, W. Domcke, Science 2004, 306,
1765-1768.
[21] P. F. Barbara, W. Jarzeba, Adv. Photochem. 1990, 15, 1-68.
[22] P. F. Barbara, G. C. Walker, T. P. Smith, Science 1992, 256, 975-981.
[23] G. R. Fleming, R. van Grondelle, Phys. Today 1994, 47, 48-55.
[24] J. Jortner, M. Bixon (Eds.), Electron Transfer - From Isolated Molecules to Biomolecules, Part 1, [Adv.
Chem. Phys.,Vol. 106], Wiley, New York, 1999.
[25] J. Jortner, M. Bixon (Eds.), Electron Transfer - From Isolated Molecules to Biomolecules, Part 2, [Adv.
Chem. Phys.,Vol. 107], Wiley, New York, 1999.
[26] R. A. Mathies, C. H. B. Cruz, W. T. Pollard, C. V. Shank, Science 1988, 240, 777-779.
[27] R. W. Schoenlein, L. A. Peteanu, R. A. Mathies, C. V. Shank, Science 1991, 254, 412-415.
[28] R. J. Sension, S. T. Repinec, A. Z. Szarka, R. M. Hochstrasser, J. Chem. Phys. 1993, 98, 6291-6315.
[29] F. Gai, K. C. Hasson, J. C. McDonald, P. A. Anfinrud, Science 1998, 279, 1886-1891.
FEMTOSECOND STRUCTURAL DYNAMICS 23
[30] D. A. Wiersma (Ed.), Femtosecond Reaction Dynamics, [Koninklijke Nederlandse Akademie van
Wetenschappen Verhandelingen, Afd. Natuurkunde, Eerste Reeks, deel 42, North-Holland, Amsterdam,
1994.
[31] J. Manz, L. Wöste (Eds.), Femtosecond Chemistry, Vol. 1 and 2, VCH, Weinheim, 1995.
[32] V. Sundström (Ed.), Nobel Symposium: Femtochemistry and Femtobiology: Ultrafast Reaction Dynamics
at Atomic-Scale Resolution, World Scientific, Singapore, 1996.
[33] F. C. De Schryver, S. De Feyter, G. Schweitzer (Eds.), Femtochemistry, Wiley-VCH, Weinheim, 2001.
[34] M. M. Martin, J. T. Hynes (Eds.), Femtochemistry and Femtobiology: Ultrafast Events in Molecular
Science, Elsevier, Amsterdam, 2004.
[35] A. J. R. Heck, D. W. Chandler, Annu. Rev. Phys. Chem. 1995, 46, 335-372.
[36] H. Sato, Chem. Rev. 2001, 101, 2687-2725.
[37] T. P. Rakitzis, A. J. van den Brom, M. H. M. Janssen, Science 2004, 303, 1852-1854.
[38] P. Hänggi, P. Talkner, M. Borkovec, Rev. Mod. Phys. 1990, 62, 251-341.
[39] J. C. Polanyi, A. H. Zewail, Acc. Chem. Res. 1995, 28, 119-132.
[40] P. Talkner, P. Hänggi (Eds.), New Trends in Kramers' Reaction Rate Theory, [Understanding Chemical
Reactivity,Vol. 11], Kluwer, Dordrecht, 1995.
[41] J. T. Hynes, Annu. Rev. Phys. Chem. 1985, 36, 573-597.
[42] G. R. Fleming, P. G. Wolynes, Phys. Today 1990, 43, 36-43.
[43] G. R. Fleming, P. Hänggi (Eds.), Activated Barrier Crossing: Applications in Physics, Chemistry and
Biology, World Scientific, Singapore, 1993.
[44] G. A. Voth, R. M. Hochstrasser, J. Phys. Chem. 1996, 100, 13034-13049.
[45] O. Tapia, J. Bertrán (Eds.), Solvent Effects and Chemical Reactivity, [Understanding Chemical
Reactivity,Vol. 17], Kluwer, Dordrecht, 1996.
[46] C. Lienau, A. H. Zewail, J. Phys. Chem. 1996, 100, 18629-18649.
[47] A. Materny, C. Lienau, A. H. Zewail, J. Phys. Chem. 1996, 100, 18650-18665.
[48] P. C. Becker, H. L. Fragnito, J. Y. Bigot, C. H. Brito Cruz, R. L. Fork, C. V. Shank, Phys. Rev. Lett. 1989,
63, 505-507.
[49] J. Y. Bigot, M. T. Portella, R. W. Schoenlein, C. J. Bardeen, A. Migus, C. V. Shank, Phys. Rev. Lett.
1991, 66, 1138-1141.
[50] E. T. J. Nibbering, D. A. Wiersma, K. Duppen, Phys. Rev. Lett. 1991, 66, 2464-2467.
[51] E. T. J. Nibbering, K. Duppen, D. A. Wiersma, Chem. Phys. 1993, 183, 167-185.
[52] R. Jimenez, G. R. Fleming, P. V. Kumar, M. Maroncelli, Nature 1994, 369, 471-473.
[53] G. R. Fleming, M. Cho, Annu. Rev. Phys. Chem. 1996, 47, 109-134.
[54] W. P. de Boeij, M. S. Pshenichnikov, D. A. Wiersma, Annu. Rev. Phys. Chem. 1998, 49, 99-123.
[55] E. T. J. Nibbering, T. Elsaesser, Chem. Rev. 2004, 104, 1887 -1914.
[56] C. B. Harris, D. E. Smith, D. J. Russell, Chem. Rev. 1990, 90, 481-488.
[57] T. Elsaesser, W. Kaiser, Annu. Rev. Phys. Chem. 1991, 42, 83-107.
[58] J. C. Owrutsky, D. Raftery, R. M. Hochstrasser, Annu. Rev. Phys. Chem. 1994, 45, 519-555.
[59] K. B. Møller, R. Rey, J. T. Hynes, J. Phys. Chem. A 2004, 108, 1275 -1289.
[60] J. Franck, E. Rabinowitch, Trans. Faraday Soc. 1934, 30, 120.
[61] Q. L. Liu, J. K. Wang, A. H. Zewail, Nature 1993, 364, 427-430.
24 NIBBERING
[62] P. W. Anderson, P. R. Weiss, Rev. Mod. Phys. 1953, 25, 269-276.
[63] R. Kubo, J. Phys. Soc. Jpn. 1954, 9, 935-944.
[64] S. Mukamel, Principles of Nonlinear Optical Spectroscopy, [Oxford Series in Optical and Imaging
Sciences,Vol. 6], Oxford University Press, Oxford, 1995.
[65] P. W. Anderson, J. Phys. Soc. Jpn. 1954, 9, 316-339.
[66] R. Kubo, Adv. Chem. Phys. 1969, 15, 101-126.
[67] S. Mukamel, Phys. Rep. 1982, 93, 1-60.
[68] Web-information: http://www.nobel.se
Nobel web-site showing information on Nobel Laureates M. Eigen, R. G. W. Norrish and G. Porter (The
Nobel Prize in Chemistry 1967: "for their studies of extremely fast chemical reactions, effected by
disturbing the equlibrium by means of very short pulses of energy") and A. H. Zewail (The Nobel Prize in
Chemistry 1999: "for his studies of the transition states of chemical reactions using femtosecond
spectroscopy").
[69] K. H. Grellmann, A. Weller, Angew. Chem. Intl. Ed. 1960, 72, 632-633.
[70] A. Weller, Progr. React. Kin. 1961, 1, 187-213.
[71] M. Eigen, Angew. Chem. Intl. Ed. 1964, 3, 1-19.
[72] M. Eigen, W. Kruse, G. Maass, L. DeMaeyer, Progr. React. Kin. 1964, 2, 285.
[73] F. J. McClung, R. W. Hellwarth, J. Appl. Phys. 1962, 33, 828-&.
[74] E. P. Ippen, C. V. Shank, in Ultrashort Light Pulses. Picosecond Techniques and Applications, Vol. 18
(Ed.: S. L. Shapiro), Springer, Berlin, 1977, pp. 83-122.
[75] G. H. C. New, Rep. Prog. Phys. 1983, 46, 877-971.
[76] R. L. Fork, B. I. Greene, C. V. Shank, Appl. Phys. Lett. 1981, 38, 671-672.
[77] A. Baltuška, T. Udem, M. Uiberacker, M. Hentschel, E. Goulielmakis, C. Gohle, R. Holzwarth, V. S.
Yakoviev, A. Scrinzi, T. W. Hänsch, F. Krausz, Nature 2003, 421, 611-615.
[78] A. Baltuška, T. Udem, M. Uiberacker, M. Hentschel, E. Goulielmakis, C. Gohle, R. Holzwarth, V. S.
Yakovlev, A. Scrinzi, T. W. Hänsch, F. Krausz, Nature 2003, 422, 189-189.
[79] R. Kienberger, E. Goulielmakis, M. Uiberacker, A. Baltuška, V. Yakovlev, F. Bammer, A. Scrinzi, T.
Westerwalbesloh, U. Kleineberg, U. Heinzmann, M. Drescher, F. Krausz, Nature 2004, 427, 817-821.
[80] D. E. Spence, P. N. Kean, W. Sibbett, Opt. Lett. 1991, 16, 42-44.
[81] P. F. Moulton, J. Opt. Soc. Am. B 1986, 3, 125-133.
[82] R. Ell, U. Morgner, F. X. Kärtner, J. G. Fujimoto, E. P. Ippen, V. Scheuer, G. Angelow, T. Tschudi, M. J.
Lederer, A. Boiko, B. Luther-Davies, Opt. Lett. 2001, 26, 373-375.
[83] P. Maine, D. Strickland, P. Bado, M. Pessot, G. Mourou, IEEE J. Quantum Electron. 1988, 24, 398-403.
[84] D. Strickland, G. Mourou, Opt. Commun. 1985, 56, 219-221.
[85] S. Backus, C. G. Durfee, III, M. M. Murnane, H. C. Kapteyn, Rev. Sci. Instrum. 1998, 69, 1207-1223.
[86] T. Brabec, F. Krausz, Rev. Mod. Phys. 2000, 72, 545-591.
[87] F. Salin, J. Squier, G. Mourou, Opt. Lett. 1991, 16, 1964-1966.
[88] J. V. Rudd, G. Korn, S. Kane, J. Squier, G. Mourou, P. Bado, Opt. Lett. 1993, 18, 2044-2046.
[89] S. Backus, J. Peatross, C. P. Huang, M. M. Murnane, H. C. Kapteyn, Opt. Lett. 1995, 20, 2000-2002.
[90] M. Lenzner, C. Spielmann, E. Wintner, F. Krausz, A. J. Schmidt, Opt. Lett. 1995, 20, 1397-1399.
FEMTOSECOND STRUCTURAL DYNAMICS 25
[91] S. Sartania, Z. Cheng, M. Lenzner, G. Tempea, C. Spielmann, F. Krausz, K. Ferencz, Opt. Lett. 1997, 22,
1562-1564.
[92] M. Nisoli, S. DeSilvestri, O. Svelto, Appl. Phys. Lett. 1996, 68, 2793-2795.
[93] M. Nisoli, S. DeSilvestri, O. Svelto, R. Szipocs, K. Ferencz, C. Spielmann, S. Sartania, F. Krausz, Opt.
Lett. 1997, 22, 522-524.
[94] E. T. J. Nibbering, O. Dühr, G. Korn, Opt. Lett. 1997, 22, 1335-1337.
[95] O. Dühr, E. T. J. Nibbering, G. Korn, Appl. Phys. B 1998, B67, 525-527.
[96] O. Dühr, E. T. J. Nibbering, G. Korn, G. Tempea, F. Krausz, Opt. Lett. 1999, 24, 34-36.
[97] T. Wilhelm, J. Piel, E. Riedle, Opt. Lett. 1997, 22, 1494-1496.
[98] G. Cerullo, M. Nisoli, S. Stagira, S. De Silvestri, Opt. Lett. 1998, 23, 1283-1285.
[99] A. Shirakawa, I. Sakane, M. Takasaka, T. Kobayashi, Appl. Phys. Lett. 1999, 74, 2268-2270.
[100] A. Kummrow, M. Wittmann, F. Tschirschwitz, G. Korn, E. T. J. Nibbering, Appl. Phys. B 2000, B71,
885-887.
[101] G. Cerullo, S. De Silvestri, Rev. Sci. Instrum. 2003, 74, 1-18.
[102] P. Hamm, R. A. Kaindl, J. Stenger, Opt. Lett. 2000, 25, 1798-1800.
[103] R. A. Kaindl, M. Wurm, K. Reimann, P. Hamm, A. M. Weiner, M. Woerner, J. Opt. Soc. Am. B 2000, 17,
2086-2094.
[104] K. Reimann, R. P. Smith, A. M. Weiner, T. Elsaesser, M. Woerner, Opt. Lett. 2003, 28, 471-473.
[105] Y. R. Shen, The Principles of Nonlinear Optics, Wiley, New York, 1984.
[106] A. M. Weiner, Rev. Sci. Instrum. 2000, 71, 1929-1960.
[107] W. S. Warren, H. Rabitz, M. Dahleh, Science 1993, 259, 1581-1589.
[108] A. Assion, T. Baumert, M. Bergt, T. Brixner, B. Kiefer, V. Seyfried, M. Strehle, G. Gerber, Science 1998,
282, 919-922.
[109] H. Rabitz, R. de Vivie-Riedle, M. Motzkus, K. Kompa, Science 2000, 288, 824-828.
[110] T. Brixner, N. H. Damrauer, P. Niklaus, G. Gerber, Nature 2001, 414, 57-60.
[111] J. L. Herek, W. Wohlleben, R. J. Cogdell, D. Zeidler, M. Motzkus, Nature 2002, 417, 533-535.
[112] C. Daniel, J. Full, L. González, C. Lupulescu, J. Manz, A. Merli, S. Vajda, L. Wöste, Science 2003, 299,
536-539.
[113] D. A. Wiersma, K. Duppen, Science 1987, 237, 1147-1154.
[114] C. A. Walsh, M. Berg, L. R. Narasimhan, M. D. Fayer, Acc. Chem. Res. 1987, 20, 120-126.
[115] L. R. Narasimhan, K. A. Littau, D. W. Pack, Y. S. Bai, A. Elschner, M. D. Fayer, Chem. Rev. 1990, 90,
439-457.
[116] N. P. Ernsting, S. A. Kovalenko, T. Senyushkina, J. Saam, V. Farztdinov, J. Phys. Chem. A 2001, 105,
3443-3453.
[117] K. Duppen, D. A. Wiersma, J. Opt. Soc. Am. B 1986, 3, 614-621.
[118] A. M. Weiner, S. De Silvestri, E. P. Ippen, J. Opt. Soc. Am. B 1985, 2, 654-662.
[119] W. P. de Boeij, M. S. Pshenichnikov, D. A. Wiersma, Chem. Phys. Lett. 1996, 253, 53-60.
[120] T. Joo, Y. Jia, J.-Y. Yu, M. J. Lang, G. R. Fleming, J. Chem. Phys. 1996, 104, 6089-6108.
[121] K. Duppen, D. P. Weitekamp, D. A. Wiersma, Chem. Phys. Lett. 1984, 108, 551-554.
[122] M. Yang, G. R. Fleming, J. Chem. Phys. 1999, 110, 2983-2990.
[123] W. P. de Boeij, M. S. Pshenichnikov, D. A. Wiersma, Chem. Phys. Lett. 1995, 238, 1-8.
26 NIBBERING
[124] M. L. Cowan, J. P. Ogilvie, R. J. D. Miller, Chem. Phys. Lett. 2004, 386, 184-189.
[125] T. Brixner, I. V. Stiopkin, G. R. Fleming, Opt. Lett. 2004, 29, 884-886.
[126] E. J. Heller, Acc. Chem. Res. 1981, 14, 368-375.
[127] L. Dhar, J. A. Rogers, K. A. Nelson, Chem. Rev. 1994, 94, 157-193.
[128] S. J. Rosenthal, X. Xiaoliang, D. Mei, G. R. Fleming, J. Chem. Phys. 1991, 95, 4715-4718.
[129] D. M. Jonas, Annu. Rev. Phys. Chem. 2003, 54, 425-463.
[130] S. Mukamel, D. Abramavicius, Chem. Rev. 2004, 104, 2073-2098.
[131] T. Brixner, J. Stenger, H. M. Vaswani, M. Cho, R. E. Blankenship, G. R. Fleming, Nature 2005, 434, 625-
628.
[132] V. Sundström, T. Pullerits, R. van Grondelle, J. Phys. Chem. B 1999, 103, 2327-2346.
[133] G. R. Fleming, G. D. Scholes, Nature 2004, 431, 256-257.
[134] C. Chudoba, E. T. J. Nibbering, T. Elsaesser, Phys. Rev. Lett. 1998, 81, 3010-3013.
[135] C. Chudoba, E. T. J. Nibbering, T. Elsaesser, J. Phys. Chem. A 1999, 103, 5625-5628.
[136] E. T. J. Nibbering, C. Chudoba, T. Elsaesser, Isr. J. Chem. 1999, 39, 333-347.
[137] M. Rini, A. Kummrow, J. Dreyer, E. T. J. Nibbering, T. Elsaesser, Faraday Discuss. 2003, 122, 27-40.
[138] M. Rini, J. Dreyer, E. T. J. Nibbering, T. Elsaesser, Chem. Phys. Lett. 2003, 374, 13-19.
[139] A. Novak, Struct. Bonding (Berlin) 1974, 18, 177-216.
[140] D. Hadži, S. Bratos, in The Hydrogen Bond: Recent developments in theory and experiments, Vol. II.
Structure and Spectroscopy (Eds.: P. Schuster, G. Zundel, C. Sandorfy), North Holland, Amsterdam, the
Netherlands, 1976, pp. 565-611.
[141] E. T. J. Nibbering, T. Elsaesser, Appl. Phys. B 2000, B71, 439-441.
[142] E. T. J. Nibbering, F. Tschirschwitz, C. Chudoba, T. Elsaesser, J. Phys. Chem. A 2000, 104, 4236-4246.
[143] M. Rini, B.-Z. Magnes, E. Pines, E. T. J. Nibbering, Science 2003, 301, 349-352.
[144] M. Rini, D. Pines, B. Z. Magnes, E. Pines, E. T. J. Nibbering, J. Chem. Phys. 2004, 121, 9593-9610.
[145] C. Chudoba, A. Kummrow, J. Dreyer, J. Stenger, E. T. J. Nibbering, T. Elsaesser, K. A. Zachariasse,
Chem. Phys. Lett. 1999, 309, 357-363.
[146] J. Dreyer, A. Kummrow, J. Am. Chem. Soc. 2000, 122, 2577-2585.
[147] A. Kummrow, J. Dreyer, C. Chudoba, J. Stenger, E. T. J. Nibbering, T. Elsaesser, J. Chin. Chem. Soc.
2000, 47, 721-728.
[148] B. O. Roos, K. Andersson, M. P. Fulscher, P.-Å. Malmqvist, L. Serrano Andre's, K. Pierloot, M.
Mercha'n, Adv. Chem. Phys. 1996, 93, 219-331.
[149] M. A. L. Marques, E. K. U. Gross, Annu. Rev. Phys. Chem. 2004, 55, 427-455.
[150] O. F. Mohammed, J. Dreyer, B.-Z. Magnes, E. Pines, E. T. J. Nibbering, ChemPhysChem 2005, 6, 625-
636.
[151] P. Hamm, S. M. Ohline, W. Zinth, J. Chem. Phys. 1997, 106, 519-529.
[152] M. Rini, A.-K. Holm, E. T. J. Nibbering, H. Fidder, J. Am. Chem. Soc. 2003, 125, 3028-3034.
[153] A.-K. Holm, M. Rini, E. T. J. Nibbering, H. Fidder, Chem. Phys. Lett. 2003, 376, 214-219.
[154] H. Fidder, M. Rini, E. T. J. Nibbering, J. Am. Chem. Soc. 2004, 126, 3789-3794.
[155] J. Bredenbeck, J. Helbing, P. Hamm, J. Am. Chem. Soc. 2004, 126, 990-991.
[156] I. V. Rubtsov, N. P. Redmore, R. M. Hochstrasser, M. J. Therien, J. Am. Chem. Soc. 2004, 126, 2684-
2685.
FEMTOSECOND STRUCTURAL DYNAMICS 27
[157] J. C. Owrutsky, A. P. Baronavski, J. Chem. Phys. 1996, 105, 9864-9873.
[158] H. Yang, K. T. Kotz, M. C. Asplund, M. J. Wilkens, C. B. Harris, Acc. Chem. Res. 1999, 32, 551-560.
[159] D. A. Steinhurst, A. P. Baronavski, J. C. Owrutsky, Chem. Phys. Lett. 2002, 361, 513-519.
[160] F. Schotte, M. H. Lim, T. A. Jackson, A. V. Smirnov, J. Soman, J. S. Olson, G. N. Phillips, M. Wulff, P.
A. Anfinrud, Science 2003, 300, 1944-1947.
[161] J. S. Yeston, T. T. To, T. J. Burkey, E. J. Heilweil, J. Phys. Chem. B 2004, 108, 4582-4585.
[162] V. Lehtovuori, J. Aumanen, P. Myllyperkiö, M. Rini, E. T. J. Nibbering, J. Korppi-Tommola, J. Phys.
Chem. A 2004, 108, 1644-1649.
[163] T. Zemojtel, M. Rini, K. Heyne, T. Dandekar, E. T. J. Nibbering, P. M. Kozlowski, J. Am. Chem. Soc.
2004, 126, 1930-1931.
[164] J. Herbst, K. Heyne, R. Diller, Science 2002, 297, 822-825.
[165] J. Bredenbeck, J. Helbing, R. Behrendt, C. Renner, L. Moroder, J. Wachtveitl, P. Hamm, J. Phys. Chem.
B 2003, 107, 8654-8660.
[166] M. L. Groot, L. J. G. W. van Wilderen, D. S. Larsen, M. A. van der Horst, I. H. M. van Stokkum, K. J.
Hellingwerf, R. van Grondelle, Biochemistry 2003, 42, 10054-10059.
[167] A. Usman, O. F. Mohammed, K. Heyne, J. Dreyer, E. T. J. Nibbering, Chem. Phys. Lett. 2005, 401, 157-
163.
[168] K. Wynne, R. M. Hochstrasser, Chem. Phys. 1995, 193, 211-236.
[169] P. Hamm, Chem. Phys. 1995, 200, 415-429.
[170] W. M. Kwok, C. Ma, P. Matousek, A. W. Parker, D. Phillips, W. T. Toner, M. Towrie, S. Umapathy, J.
Phys. Chem. A 2001, 105, 984 -990.
[171] C. Ma, W. M. Kwok, P. Matousek, A. W. Parker, D. Phillips, W. T. Toner, M. Towrie, J. Phys. Chem. A
2002, 106, 3294-3305.
[172] P. Matousek, M. Towrie, A. Stanley, A. W. Parker, Appl. Spectrosc. 1999, 53, 1485-1489.
[173] Y. Zhou, L. Ujj, T. E. Meyer, M. A. Cusanovich, G. H. Atkinson, J. Phys. Chem. A 2001, 105, 5719-
5726.
[174] G. H. Atkinson, Y. Zhou, L. Ujj, A. Aharoni, M. Sheves, M. Ottolenghi, J. Phys. Chem. A 2002, 106,
3325-3336.
[175] A. C. Terentis, Y. D. Zhou, G. H. Atkinson, L. Ujj, J. Phys. Chem. A 2003, 107, 10787-10797.
[176] S. Hogiu, W. Werncke, M. Pfeiffer, T. Elsaesser, Chem. Phys. Lett. 1999, 312, 407-414.
[177] S. Hogiu, W. Werncke, M. Pfeiffer, J. Dreyer, T. Elsaesser, J. Chem. Phys. 2000, 113, 1587-1594.
[178] V. Kozich, W. Werncke, J. Dreyer, K. W. Brzezinka, M. Rini, A. Kummrow, T. Elsaesser, J. Chem. Phys.
2002, 117, 719-726.
[179] V. Kozich, W. Werncke, A. I. Vodchits, J. Dreyer, J. Chem. Phys. 2003, 118, 1808-1814.
[180] M. D. Fayer (Ed.), Ultrafast infrared and Raman spectroscopy, [Practical Spectroscopy Series,Vol. 26],
Marcel Dekker, Inc., New York, 2001.
[181] P. Hamm, R. M. Hochstrasser, in Ultrafast infrared and Raman spectroscopy, Vol. 26 (Ed.: M. D. Fayer),
Marcel Dekker, Inc., New York, 2001, pp. 273-347.
[182] M. Lim, P. Hamm, R. M. Hochstrasser, Proc. Natl. Acad. Sci. USA 1998, 95, 15315-15320.
[183] P. Hamm, M. Lim, R. M. Hochstrasser, J. Phys. Chem. B 1998, 102, 6123-6138.
[184] P. Hamm, M. Lim, W. F. DeGrado, R. M. Hochstrasser, J. Phys. Chem. A 1999, 103, 10049-10053.
28 NIBBERING
[185] M. T. Zanni, M. C. Asplund, R. M. Hochstrasser, J. Chem. Phys. 2001, 114, 4579-4590.
[186] J. Stenger, D. Madsen, J. Dreyer, E. T. J. Nibbering, P. Hamm, T. Elsaesser, J. Phys. Chem. A 2001, 105,
2929-2932.
[187] D. Madsen, J. Stenger, J. Dreyer, P. Hamm, E. T. J. Nibbering, T. Elsaesser, Bull. Chem. Soc. Jpn. 2002,
75, 909-917.
[188] K. Heyne, N. Huse, E. T. J. Nibbering, T. Elsaesser, Chem. Phys. Lett. 2003, 369, 591-596.
[189] K. Heyne, N. Huse, E. T. J. Nibbering, T. Elsaesser, J. Phys. Condens. Mat. 2003, 15, S129-S136.
[190] K. Heyne, N. Huse, J. Dreyer, E. T. J. Nibbering, T. Elsaesser, S. Mukamel, J. Chem. Phys. 2004, 121,
902-913.
[191] J. Stenger, D. Madsen, J. Dreyer, P. Hamm, E. T. J. Nibbering, T. Elsaesser, Chem. Phys. Lett. 2002, 354,
256-263.
[192] N. Huse, K. Heyne, J. Dreyer, E. T. J. Nibbering, T. Elsaesser, Phys. Rev. Lett. 2003, 91, 197401.
[193] A. Tokmakoff, M. D. Fayer, Acc. Chem. Res. 1995, 28, 437-445.
[194] K. D. Rector, M. D. Fayer, Int. Rev. Phys. Chem. 1998, 17, 261-306.
[195] P. Hamm, M. Lim, R. M. Hochstrasser, Phys. Rev. Lett. 1998, 81, 5326-5329.
[196] G. M. Gale, G. Gallot, F. Hache, N. Lascoux, S. Bratos, J. C. Leicknam, Phys. Rev. Lett. 1999, 82, 1068-
1071.
[197] S. Woutersen, H. J. Bakker, Phys. Rev. Lett. 1999, 83, 2077-2080.
[198] J. Stenger, D. Madsen, P. Hamm, E. T. J. Nibbering, T. Elsaesser, Phys. Rev. Lett. 2001, 87, 027401.
[199] J. Stenger, D. Madsen, P. Hamm, E. T. J. Nibbering, T. Elsaesser, J. Phys. Chem. A 2002, 106, 2341-
2350.
[200] S. Yeremenko, M. S. Pshenichnikov, D. A. Wiersma, Chem. Phys. Lett. 2003, 369, 107-113.
[201] C. J. Fecko, J. D. Eaves, J. J. Loparo, A. Tokmakoff, P. L. Geissler, Science 2003, 301, 1698-1702.
[202] J. B. Asbury, T. Steinel, C. Stromberg, S. A. Corcelli, C. P. Lawrence, J. L. Skinner, M. D. Fayer, J. Phys.
Chem. A 2004, 108, 1107-1119.
[203] R. Rey, K. B. Møller, J. T. Hynes, J. Phys. Chem. A 2002, 106, 11993-11996.
[204] C. P. Lawrence, J. L. Skinner, J. Chem. Phys. 2003, 118, 264-272.
[205] M. L. Cowan, B. D. Bruner, N. Huse, J. R. Dwyer, B. Chugh, E. T. J. Nibbering, T. Elsaesser, R. J. D.
Miller, Nature 2005, 434, 199-202.
[206] N. Huse, S. Ashihara, E. T. J. Nibbering, T. Elsaesser, Chem. Phys. Lett. 2005, 404, 389-393.
[207] K. Heyne, N. Huse, E. T. J. Nibbering, T. Elsaesser, Chem. Phys. Lett. 2003, 382, 19-25.
[208] K. Heyne, E. T. J. Nibbering, T. Elsaesser, M. Petković, O. Kühn, J. Phys. Chem. A 2004, 108, 6083-
6086.
[209] J. C. Deàk, S. T. Rhea, L. K. Iwaki, D. D. Dlott, J. Phys. Chem. A 2000, 104, 4866-4875.
[210] D. W. Oxtoby, D. Levesque, J. J. Weis, J. Chem. Phys. 1978, 68, 5528-5533.
[211] D. W. Oxtoby, Adv. Chem. Phys. 1979, 40, 1-48.
[212] R. Rey, K. B. Møller, J. T. Hynes, Chem. Rev. 2004, 104, 1915-1928.
[213] C. P. Lawrence, J. L. Skinner, J. Chem. Phys. 2003, 119, 1623-1633.
[214] C. P. Lawrence, J. L. Skinner, J. Chem. Phys. 2003, 119, 3840-3848.
[215] M. Wollenhaupt, V. Engel, T. Baumert, Annu. Rev. Phys. Chem. 2005, 56, 25-56.
[216] T. Witte, K. L. Kompa, M. Motzkus, Appl. Phys. B 2003, 76, 467-471.
FEMTOSECOND STRUCTURAL DYNAMICS 29
[217] M. Khalil, N. Demirdöven, A. Tokmakoff, J. Phys. Chem. A 2003, 107, 5258-5279.
[218] S. Mukamel, Annu. Rev. Phys. Chem. 2000, 51, 691-729.
[219] H. Ihee, V. A. Lobastov, U. M. Gomez, B. M. Goodson, R. Srinivasan, C. Y. Ruan, A. H. Zewail, Science
2001, 291, 458-462.
[220] C. Y. Ruan, V. A. Lobastov, R. Srinivasan, B. M. Goodson, H. Ihee, A. H. Zewail, Proc. Natl. Acad. Sci.
USA 2001, 98, 7117-7122.
[221] B. J. Siwick, J. R. Dwyer, R. E. Jordan, R. J. D. Miller, Science 2003, 302, 1382-1385.
[222] C. Y. Ruan, F. Vigliotti, V. A. Lobastov, S. Y. Chen, A. H. Zewail, Proc. Natl. Acad. Sci. USA 2004, 101,
1123-1128.
[223] C. Y. Ruan, V. A. Lobastov, F. Vigliotti, S. Y. Chen, A. H. Zewail, Science 2004, 304, 80-84.
[224] C. Rischel, A. Rousse, I. Uschmann, P. A. Albouy, J. P. Geindre, P. Audebert, J. C. Gauthier, E. Forster,
J. L. Martin, A. Antonetti, Nature 1997, 390, 490-492.
[225] C. W. Siders, A. Cavalleri, K. Sokolowski-Tinten, C. Toth, T. Guo, M. Kammler, M. H. von Hoegen, K.
R. Wilson, D. von der Linde, C. P. J. Barty, Science 1999, 286, 1340-1342.
[226] M. F. DeCamp, D. A. Reis, P. H. Bucksbaum, B. Adams, J. M. Caraher, R. Clarke, C. W. S. Conover, E.
M. Dufresne, R. Merlin, V. Stoica, J. K. Wahlstrand, Nature 2001, 413, 825-828.
[227] D. A. Reis, M. F. DeCamp, P. H. Bucksbaum, R. Clarke, E. Dufresne, M. Hertlein, R. Merlin, R. Falcone,
H. Kapteyn, M. M. Murnane, J. Larsson, T. Missalla, J. S. Wark, Phys. Rev. Lett. 2001, 86, 3072-3075.
[228] A. Rousse, C. Rischel, S. Fourmaux, I. Uschmann, S. Sebban, G. Grillon, P. Balcou, E. Foster, J. P.
Geindre, P. Audebert, J. C. Gauthier, D. Hulin, Nature 2001, 410, 65-68.
[229] E. Collet, M. H. Lemee-Cailleau, M. Buron-Le Cointe, H. Cailleau, M. Wulff, T. Luty, S. Y. Koshihara,
M. Meyer, L. Toupet, P. Rabiller, S. Techert, Science 2003, 300, 612-615.
[230] K. Sokolowski-Tinten, C. Blome, J. Blums, A. Cavalleri, C. Dietrich, A. Tarasevitch, I. Uschmann, E.
Forster, M. Kammler, M. Horn-von-Hoegen, D. von der Linde, Nature 2003, 422, 287-289.
[231] M. Bargheer, N. Zhavoronkov, Y. Gritsai, J. C. Woo, D. S. Kim, M. Woerner, T. Elsaesser, Science 2004,
306, 1771-1773.
[232] F. Raksi, K. R. Wilson, J. Zhimig, A. Ikhlef, C. Y. Cote, J. C. Kieffer, J. Chem. Phys. 1996, 104, 6066-
6069.
30 NIBBERING