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IAMS, Academia Sinica, Taiwan, 台灣 中研院原分所
Course: Molecular Spectroscopy
Taiwan International Graduate Program (TIGP)
Professor: Wen-Bih Tzeng, Lab: 108, Office: 301e-mail : [email protected] : http://www.iams.sinica.edu.tw/lab/wbtzeng/indexa.html
3 lectures on electronic spectroscopy of molecules in the gas phaseTuesday 9:10-12:00, 2013/2/19 - 2012/3/5 (Classroom: 311)
Suggested books (NTU Chemistry Library):1. Modern Spectroscopy, 4th ed. by J. Michael Hollas, John Wiley & Sons, 2004.2. Molecular Spectra and Molecular Structure, G. Herzberg, D. van Nostrand Company, Inc., QC 451.H463v.1 1950.
Lecture Planning
Date
2013/02/19 (Tue) Introduction Some Important Results in Quantum MechanicsElectromagnetic Radiation and its Interaction with Atoms and Molecules (Chapter 1)
2013/02/26 (Tue) Electromagnetic Radiation and its Interaction with Atoms and Molecules (Chapter 2) Electronic spectroscopy (Chapter 7)
2013/03/05 (Tue) Photoelectron spectroscopy and related spectroscopies (REMPI, ZEKE, MATI spectroscopy)
Energy Levels
C6H5NH2+, D0
(7.7206 eV)
(293.87 nm)
IE = 62,271 cm-1
E = 34,029 cm-1
C6H5NH2, S0
C6H5NH2*, S1
Energy Level of Aniline
wbt 5S0
S1
D0 R**
1C-R2PI 2C-R2PI MATI
PFI
Resonant two-photon (R2PI) and mass-analyzedthreshold ionization (MATI) processes
electronicexcitation
ionization
N
H
H
HH
HH
H
Preparation of C6H5NHD and C6H5ND2
+ D2O N
H
D
HH
HH
H
N
D
D
HH
HH
H
(Mass 93)
(Mass 95)
(Mass 94)
Preparation of C6D5NHD and C6D5ND2
+
(Mass 100)
(Mass 98)
(Mass 99)
N
D
D
DD
DD
D N
H
D
DD
DD
D
N
H
H
DD
DD
D
H2O
92 96 100 104 108
100(c)
9998(b)
94
93
(a)
Rel
ativ
e In
tens
ity
Mass / amu
TOF spectra of deuterium substituted aniline isotopomers
λ = 293.94 nm
λ = 292.54 nm
λ = 292.48 nm
93 ↔ C6H5NH2+
94 ↔ C6H5NHD+
98 ↔ C6D5NH2+
99 ↔ C6D5NHD+
100 ↔ C6D5ND2+
One photon energy / cm-1
34000 34200 34400 34600 34800 35000 35200
34038 cm-1
1201
101
I02
6a0100
0(c)
34031 cm-1 1201
101I
02
6a010
00
(b)
34029 cm-1 1201
101
I02
6a01
000
(a)
Rel
ativ
e In
tens
ity
(a) C6H5NH2
(b) C6H5NHD
(b) C6H5ND2
Vibronic spectra of deuterium substituted aniline isotopomers
Vibronic spectra of deuterium substituted aniline isotopomers
Relative Wavenumber / cm-1
Rel
ativ
e In
tens
ity
0 200 400 600 800 1000
34202 cm-1
1201
I026a
01
000(c)
(a)
34195 cm-112
01
I02
6a010
00(b)
34193 cm-1
1201
I02
6a01
000
(a) C6D5NH2
(b) C6D5NHD
(c) C6D5ND2
MATI spectra of deuterium substituted aniline isotopomers
Ion Internal Energy / cm-1
Rel
ativ
e In
tens
ity
0 400 800 1200 1600
62233 cm-1
8a1
9a1121
10b211
0+ (c)
62253 cm-1
8a1
9a112110b2 11
0+ (b)
62271 cm-1
9a1121
11
16a2
10b2
0+ (a)
via S100
via S100
via S100
34029 cm-1
34031 cm-1
34038 cm-1
(a) C6H5NH2
(b) C6H5NHD
(c) C6H5ND2
Ion Internal Energy / cm-1
Rel
ativ
e In
tens
ity
via S100
via S100
via S100
34193 cm-1
34195 cm-1
34202 cm-1
(a) C6D5NH2
(b) C6D5NHD
(c) C6D5ND2
MATI spectra of deuterium substituted aniline isotopomers
0 400 800 1200 1600
62214 cm-1
6a1
121
118a1
0+ (c)
62237 cm-1
6a1
18a1
18a1
11
8a10+ (b)
6a1
62258 cm-1
121
18a1
118a1
0+ (a)
13
Vibronic spectra of m-, o-, p-fluoroanilineby 1C-R2PI
14
Vibronic spectra of m-, o-, p-fluoroanilineby 1C-R2PI
15
Vibronic spectrum of m- and o-fluoroaniline mixture
16
MATI spectra of m-, o-, p-fluoroaniline
m-fluoroanilineNIST: 8.32 - 8.33 eVMATI: 7.9543 ± 0.0006 eV
o-fluoroanilineNIST: 8.2 - 8.5 eVMATI: 7.8909 ± 0.0006 eV
p-fluoroanilineNIST: 7.9 - 8.2 eVMATI: 7.7543 ± 0.0006 eV
17
Vibronic spectra of m-, o-, p-fluoroanisole
m-fluoroanisole has cis and trans rotamers.
18
MATI spectra of m-, o-, p-fluoroanisoletrans-m-fluoroanisoleNIST: 8.4 - 8.7 eVMATI: 8.4686 ± 0.0006 eV
cis-m-fluoroanisoleNIST: 8.4 - 8.7 eVMATI: 8.4144 ± 0.0006 eV
o-fluoroanisoleNIST: -MATI: 8.3508 ± 0.0006 eV
p-fluoroanisoleNIST: 8.3 - 8.6 eVMATI: 8.2371 ± 0.0006 eV
IR and REMPI spectra of guanine
Ref: (a) IR: Delabar et al., Spectrochim Acta 34A, 129 (1978). (b) REMPI: de Vries and coworkers, JACS 121, 4896 (1999).
Possible structures of guanine
(c)
(b) (a)
Ref: de Vries and coworkers, JCP 115, 4606 (2001).
292 293 294 295 296 297 298 299 300 301 302 303 304 305
Ion
inte
nsity
Wavelength / nm
REMPI spectrum of guanine
Ref: SC Yang, JL Lin, Lab 108, IAMS
REMPI spectrum of guanine
Ref: SC Yang, JL Lin, Lab 108, IAMS
32800 33000 33200 33400 33600 33800 34000 34200
000, (c)
000, (a)
000, (b)
32864 cm-1
One photon energy / cm-1
Ion
inte
nsity
MP2/6-311G(d,p): a=7H-Keto, 1 kJ/molb=9H-Keto, 4 kJ/molc=9H-Enol, 0 kJ/mol
REMPI spectrum of guanine
Ref: SC Yang, JL Lin, Lab 108, IAMS
0 200 400 600 800 1000 1200
000, (a)
000, (b)
000, (c)
Ion
inte
nsity
Relative wavenumber / cm-1
32864 cm-1
MP2/6-311G(d,p): a=7H-Keto, 1 kJ/molb=9H-Keto, 4 kJ/molc=9H-Enol, 0 kJ/mol