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 ： wbt@po.iams.sinica.edu.twwebsite ： 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