2013.11.14
Carl-Zeiss Lecture 3
IPHT Jena
Time-resolved Raman
Spectroscopy
Hiro-o HAMAGUCHI
Department of Applied Chemistry and Institute of Molecular
Science, College of Science, National Chiao Tung University,
Taiwan
「諸行無常」
Nothing can last for ever
Time and Space: When？ Where？
Sun set at Shinjiko Lake. http://blogs.yahoo.co.jp/naru3075/41266684.html
Space
Time
10 cm
109 s
Organ
10 mm
103 s
Cell
1 mm
102 s
Organelle
Biology
Ionic liquid
Liposome
Solvation structure
Chemistry
10 nm
10-10 s
Aggregate
Complex
1 nm
0.1 nm
10-12 s
10-15 s
Molecule
Atom
Physics
Structures of Diphenylacetylene in Different Electronic States
2099 cm-1
1567 cm-1
1974 cm-1
2223 cm-1
Time-resolved Raman Spectroscopy of a Dividing Yeast
0min
6min
11min
24min
31min
41min
53min
62min
69min
72min
1500
1000
-1
500
Wavenumber / cm
Y-S Huang, T. Karashima, M. Yamamoto, H. Hamaguchi, J. Raman Spectrosc., 34, 1-3 (2003).
How Does Chemical Reaction Proceed?
When？ Where？
http://www.ed.kanazawa-u.ac.jp/~kashida/ChemII/chapter1/sec1/c112.htm
Photophysics and Photochemistry of Molecules
Optical transition
Vibrational relaxation
Internal conversion
Intersystem crossing
S2
Chemical
Reactions
S1
Phosphorescenc
Fluorescence
Photoexcitation
S0
T1
Nanosecond Transient Raman Spectrometer (1983)
Photochemical Hydrogen Abstraction Reaction of Benzophenone
3
*
H-atom
abstraction
O
Benzophenone
in the T1 state
(T1-BP)
h ISC
2
OH
H
OH
Benzophenone
ketyl radical
(BPK)
Benzhydrol
(BH)
HO
OH
O
Benzophenone
(BP)
Benzopinacole
Nanosecond Time-resolved Raman Spectroscopy of BP in CCl4
Probe: 532 nm
Tn
Pump + Probe
5 ns duration
15 ns delay
S1
Pump: 266 nm
Intersystem
crossing
T1
Probe only
5 ns duration
S0
T. Tahara, H. Hamaguchi and M. Tasumi, JPC (1987).
T1 Raman Spectra of Isotopically Substituted Benzophenones
Fig.5
d10
d513C
d5
h1013C
h10
in the T1 state
(T1-BP)
ketyl radical
(BPK)
OH
Benzhydrol
Raman Spectrum and Structure
(BH) of T1 Benzophenone
O
1658 cm-1
Benzophenone
(BP)
1800
1222 cm-1
h ISC
HO
T1 state
Benzopinacole
CO stretch
S0 state
1400
1000
Raman Shift / cm-1
OH
600
Photoisomerization of Trans-Stilbene
Why, when and how rotation occurs in the excited state?
Solvent-dependent
isomerization rate
Hexane 70 ps
Dodecane 120 ps
h
Probe solvent dependent structure and dynamics of S1 trans-stilbene by timeresolved Raman spectroscopy
Nanosecond Transient Raman Spectrum
of S1 Trans-Stilbene (1983)
H. Hamaguchi, C. Kato, M. Tasumi, Chem. Phys. Lett., 100, 3-7 (1983).
Picosecond Transform-limited Time-resolved Raman Spectrometer
pulse compressor
AO
sync. pumped
dye laser
SHG
82 MHz
588 nm
cw mode-locked Nd:YAG laser
cw Nd:YAG regenerative amplifier
dye
amplifier
SHG
Sn
PD
588 nm
3.2 ps
3.5 cm-1
UV cut filter
pump
294 nm
2.2 ps
sample
polychromator
band-reject
filter
multichannel detector
(CCD)
SHG
S1
dichroic
mirror
294 nm
2.2 ps
probe
dichroic
mirror
variable
ND
588 nm
3.2 ps
3.5 cm-1
S0
optical
delay
Trans-Stilbene
Iwata, Yamaguchi, and Hamaguchi, Rev. Sci. Instrum. 64 , 2140 (1993).
Picosecond Transform-limited Time-resolved Raman
Spectroscopy
10
Accurate peak position
and band shape
 / cm
-1
8
6
Obs
-1
(t = 3.2 ps,  = 3.5 cm )
4
2
0
0
2
4
6
t / ps
8
10
Picosecond Time-resolved Raman Spectra of S1 trans-Stilbene in CHCl3
-10 ps
-2 ps
-1 ps
0 ps
1 ps
Pump 294 nm
Probe 588 nm (0.1 mW)
C=C stretch vibration
1560 cm-1: double bond
2 ps
3 ps
5 ps
7 ps
10 ps
15 ps
20 ps
30 ps
40 ps
50 ps
70 ps
100 ps
1700
1600
Why rotation occurs
around a double bond ?
1500 1400 1300 1200
-1
Raman Shift / cm
1100
The C=C Stretch Raman Band of S1 trans-Stilbene in Alkanes
Hexane
Heptane
Octane
Nonane
Decane
Dodecane
Hexadecane
1620
1600
1580 1560 1540
-1
Raman Shift / cm
1520
The peak position shifts to higher wavenumbers and the band width decreases
on going from hexane to hexadecane. Why?
Peak Position vs Band Width of the C=C Stretch Raman Band of S1 transStilbene In Alakne Solvents at Different Temperatures
hexane
octane
decane
Peak position / cm -1
1574
1572
1570
1568
Why does linear
Relation hold?
17
18
19
20
Bandwidth / cm-1
21
22
Peak Position of the C=C Stretch Raman Band vs the
Isomerization Rate of S1 trans-Stilbene
1578
Why does linear
relation hold ?
Peak position / cm -1
1576
Why do lines
converge ?
1574
1572
283 K
293 K
298 K
303 K
313 K
1570
1568
1566
0
5
10
kiso / s -1
15
20x10
9
Theory of Vibrational Dephasing and Band Shape
Vibrational frequency is stochastically modulated in solution
Simulation of Acetone/Acetonitrile system
O
N
C
H
双極子モーメント / D
Solventinduced
dynamic
polarization
気相
時間 /ps
Solvent-induced Dynamic Polarization of Acetone in
Acetonitrile
intensity / arb.unit
Formulation of Vibrational Band Shapes under Dynamic
Polarization
1 C=C
2 C+-CW1
Modeling
1. 0
-2
1
W2
2
: 2.04×10 -1 M
: 2.94 ×10 M
: 1.35M
: 2.29M
0. 8
0. 6
0. 4
0. 2
0. 0
960
970
1
980
990
Raman shift / cm -1
2
1000
1010
t=
(1-2)/W2
Extension of the Two Frequency Exchange Model
(a) Two Frequency Exchange Model
Hamaguchi Mol. Phys.89, 463 (1997).
W = W1t/(1+t2)
G = W1t2/(1+t2)
G / W = t
(b) Many Frequency Exchange Model
n
W = W1  (W1 / W1 )t  /(1 + t  ),
2
 =2
n
G = W1  (W1 / W1 )t  /(1 + t  ),
2
 =2
0
(c) Continuous Frequency Modulation Model
W =
W1  G (t )t /(1 + t 2 )dt


0

G (t )dt
0
G =
W1  G (t )t 2 /(1 + t 2 )dt


0

G (t )dt
G / W = t1/2 ； G(t)=exp(-ln2t2/t1/22)
2
Peak Position vs Band Width of the C=C Stretch Raman Band of
S1 trans-Stilbene In Alakne Solvents at Different Temperatures
hexane
octane
decane
Peak position / cm -1
1574
1572
1570
W = W1t/(1+t2)
G = W1t2/(1+t2)
G / W = t
t =1.4
1568
17
18
19
20
Bandwidth / cm-1
21
22
Peak Position of the C=C Stretch Raman Band vs the
Isomerization Rate of S1 trans-Stilbene
1578
1=1577.3 cm-1
Peak position / cm -1
1576
1574
1572
283 K
293 K
298 K
303 K
313 K
1570
1568
1566
0
5
10
kiso / s -1
15
20x10
9
Peak Position of the C=C Stretch Raman Band vs the
Isomerization Rate of S1 trans-Stilbene
0
W =0
W1 / s-1
W = W1t/(1+t2)
1
W / cm-1
t =1.4
2
1x1012
3
283 K
293 K
298 K
303 K
313 K
4
5
0
5
10
kiso / s -1
15
20x10
9
Peak Position of the C=C Stretch Raman Band vs the
Isomerization Rate of S1 trans-Stilbene
0
W1 / s-1
W / cm-1
1
2
1x1012
3
283 K
293 K
298 K
303 K
313 K
4
5
0
5
kiso=
W1P(T)
10
kiso / s -1
15
20x10
9
Fitting of the C=C Stretch Raman Band of S1 transStilbene by the Two Frequency Exchange Model
Fitting of the observed band shapes
Hexane
Obs
Fit
W1=2.7x1012 sec-1 (370 (fs)-1)
W = W1t/(1+t2)
W1
Dodecane
W2
W1=1.5x1012 sec-1 (670 (fs)-1)
1640
1600
1560
1520
-1
Raman shift / cm
1480
isomerization rate
Hexane 70 ps
Dodecane 120 ps
Dynamic Polarization Model of Isomerization
Hamaguchi, Iwata, CPL 208, 465 (1993).
Deckert, Iwata, Hamaguchi, J. Photochem. Photobiol. 102, 35 (1996).
Iwata, Ozawa, Hamaguchi, JCP 106, 3614 (2002).
W1
W2
kiso= W1P(T)
kiso=Aexp(-E/RT) :
Isomerization
Arrhenius formula
E=3.5 kcal mol-1 (fluorecsence lifetime)
kiso=W1P(T): Dynamic Polarization Model
E=3.5~3.7 kcal mol-1 (Raman band shape)
A new view on isomerization has come out of picosecond Raman spectroscopy !
What Are Ionic Liquids？
Liquids that are composed solely of ions
Ionic Liquids
Why are they liquids?
Green Solvents?
Liquid Structures?
Are Ionic Liquids Really Liquids in the Conventional Sense?
Liquid Crystal
Crystal
Liquid
Known condensed phases of matter
Ionic Liquid ?
Transparent but heterogeneous fluid
with well-defined local structures ?
Picosecond Energy Dissipation Dynamics
of Photoexcited S1 Trans-stilbene
Picosecond Raman Thermometer with S1 transstilbene
Transient Raman spectra
S1 trans-stilbene at 50 ps
C＝C str.
at 50 ps
pump 294 nm probe 588 nm
High
temperature
Peak position
Temperature
Low
temperautre
K. Iwata and H. Hamaguchi, J. Phys. Chem. A, 101, 632 (1997)
Raman
thermometer
37
Vibrational Cooling Process of
S１ Trans-stilbene in Decane
Time-resolved
Raman spectra
Cooling
process
Peak shift to
higher wavenumber
C=C str.
vibrational
cooling process
cooling
rate k
= 0.10 ps-1
pump 296 nm probe 592 nm
38
Correlation between
cooling rate and thermal diffusivity
Cooling rate
(Ultrafast dynamics)
Thermal diffusivity
(Bulk property)
K. Iwata and H. Hamaguchi, J. Phys. Chem. A, 101, 632 (1997).
Cooling Rate vs Thermal Diffusivity
Much faster cooling
rates in ionic liquids
Macroscopic and Microscopic Thermal Diffusion in
Ionic Liquids
Cooling rate
(microscopic)
between molecules
Thermal diffusivity
(macroscopic)
between
”Local Structures”
Absorption Spectrum of trans-stilbene in C2mimTf2N
②
①
①
325 nm excitation；
No excess energy
2500
cm-1
②
297 nm excitation；
Excess energy 2500 cm-1
Cooling Kinetics of S1trans-stilbene in C2mimTf2N
Coherent artifact
Simulation of Heat Dissipation in an Ionic Liquid
Local structure
Heat origin
Heat origin:
Hot S1 trans-stilbene + solvent
Hot S1 trans-stilbene
Temperature at the heat origin
T 
  Tr.t. = { [erf{(a /2 + nL) (4 Dth t)1 2 } +erf{(a /2  nL) (4 Dth t)1 2}]}
2 n =-

 { [erf{(b /2 + nL) (4 Dth t)1 2 } +erf{(b /2  nL) (4 Dth t)1 2 }]}
n =-

 { [erf{(c /2 + nL) (4 Dth t)1 2 } +erf{(c /2  nL) (4 Dth t)1 2 }]}
n =-
L: Size of Local Structure
a, b, c : Size of the
heat origin
K. Iwata and H. Hamaguchi,
J. Phys. Chem. A, 101, 632 (1997)

Simulation of the Cooling Kinetics
Size of local structure > 10 nm
Retinal: a prototype molecular system for
Photophysics ; closely lying excited states (S3, S2, S1, T1)
Photochemistry; photoisomerization
efficient
O
inefficient
9-cis
O
all-trans
・Asymmeric trans-cis photoisomerization ・Marked solvent effect
Photobiology; retinoid proteins
・Rhodopsin ・Bcteriorhodopsin ・Sensoryrhodopsin
Photoisomerization of All-trans Retinal
7
9
11
13
A ll-trans
15 O
13-cis
O
O
11-cis
O
9-cis
O
non-polar solvent
7-cis
polar solvent
Why?
O
Proton Pumping by Bacteriorhodopsin
All-trans isomerizes to 13-cis exclusively. Why and How?
http://anx12.bio.uci.edu
S3
What happens in the Excited electronic
States of Retinal ？
S2
S1
T1
S0
h
h
O
All-trans
9-cis
O
Nanosecond Pump/Probe Time-resolved Raman
Spectroscopy of Retinal Isomers
Tn
Probe: 532 nm
5 ns duration
S1
Pump: 355 nm
15 ns delay
Raman
Scattering
Intersystem
crossing
T1
5 ns duration
S0
H. Hamaguchi, H. Okamoto,and M. Tasumi, Chem. Lett. 1984, 549-550.
H. Hamaguchi, H. Okamoto, M. Tasumi, Y. Mukai, and Y. Koyama,
Chem. Phys. Lett. 107, 355-359 (1984).
Raman Spectra of All-trans- and 9-cis-Retinal in the T1 and S0 States
All-trans-retinal
T1 State
S0 State
9-cis-retinal
T1 State
S0 State
One-way Photoisomerization on the T1 surface
S3
S2
S1
T1
S0
h
15 ns after
excitation
h
O
All-trans
9-cis
O
10 Picosecond Time-frequency Two-dimensional
Multiplex CARS Spectroscopy of Retinal Isomers
Tn
1 
2
S1
Pump: 400 nm
500 fs duration
Intersystem
crossing

21-2
1
T1
Probe:
1 523 nm, 5 ns
S0
2 broadband, 5ns
T. Tahara, B. N. Toleutaev, and H. Hamaguchi, J. Chem. Phys. 217, 369-374 (1994).
T. Tahara and H. Hamaguchi, Rev. Sci. Instru. 65, 3332-3338 (1994).
Experimental Setup for 2-D CARS Spectroscopy
Wavenumber range: ~600 cm-1
Time-resolution: 15 ps
Picosecond Two-dimensional Multiplex CARS Spectroscopy
(2-D CARS)
Operation Principle of a Streak Camera
http://cvitae.org/content/view/180/895/
2-D CARS Image for All-trans-retinal in
Cyclohexane
Picosecond Time-resolved CARS Spectra of Retinal Isomers
in Cyclohexane
All-trans
Wavenumber / cm-1
9-cis
Wavenumber / cm-1
Population Rise of the All-trans T1 State Monitored by CARS
890 ps
Photoisomerization on the Triplet Potential Surface
S3
S2
S1
900 ps
T1
S0
Asymmetric: cis
to trans only
h
h
O
All-trans
9-cis
O
Nanosecond Pump/Probe Time-resolved Infrared
Absorption Spectroscopy of Retinal Isomers
Tn
Probe:
cw infrared continuum
S1
Pump: 347 nm
Intersystem
crossing
5 ns duration
S0
T. Yuzawa and H. Hamaguchi, J. Mol. Struct., 352, 489-495.
T. Yuzawa and H. Hamaguchi, in preparation.
T1
Nanosecond Time-resolved Infrared Absorption Spectrometer
4000 cm-1 ~ 700 cm-1
50 ns time resolution
Time-resolved Infrared Absorption Spectra of Photoexcited
All-trans-retinal in Cyclohexane
Singular Value Decomposition (SVD) Analysis
SVD Analysis of the Time-resolved Infrared Absorption Spectra of All-trans Retinal
Spectral component
Singular Values
Temporal component
SVD Analysis of the Time-resolved Infrared Absorption Spectra
of All-trans Retinal
The schematic diagram of the photoisomerization
mechanism of alltrans-retinal of All-trans-retinal
Photoisomerization
Pathway
photoisomerization
via the singlet excited state
Cyclohexane
all-trans S1
ISO = 0.27 ~0.43
(calculated)
ISC = 0.43~0.7
(literature)
[13-cis S0 + 9-cis S0]
h
[photoexcited all-trans S0 ]
all-trans T1
13-cis S0 9-cis S0
3
:
1
all-trans S0
1.0
Amplitude
1.0
Amplitude
ISO =
0.5
0.0
0.5
0.0
0
10 20 30
Time / ms
40
0
10 20 30
Time / ms
40
QY_estimation4
in
Two Relaxation Pathway of the Photoexcited All-trans-retinal
S3
S2
S1
T1
S0
h
5 ms
<< 50 ns
O
All-trans
9-cis
O
Femtosecond Pump/Probe Time-resolved Visible and
Ultraviolet Absorption Spectroscopy of Retinal Isomers
Tn
Probe:
S3
S2
Femtosecond
White Cntinuum
S1
Pump:
Intersystem
crossing
400 nm
T1
50 fs duration
S0
S. Yamaguchi and H. Hamaguchi, J. Mol. Struct. 379, 87-92 (1996).
S. Yamaguchi and H. Hamaguchi, J. Chem. Phys. 109, 1397-1408 (1998).
H. Minami and H. Hamaguchi, to be published.
Femtosecond Time-resolved Visible/Ultraviolet Absorption System
Chirp Correction for the Observed Femtosecond Timeresolved Absorption Spectra
Femtosecond Time-resolved Visible Absorption Spectra in Hexane
All-trans
Wavelength / nm
9-cis
Wavelength / nm
Cascading Decay Kinetics of Photoexcited All-trans-retinal in
Heptane
Excitation: 400 nm
Femtosecond Photoexcitation Dynamics of Retinal Isomers
S3
S2
50 fs
50 fs
S1
700 fs
400 fs
900 ps
32 ps
34 ps
T1
S0
h
h
5 ms
O
All-trans
9-cis
O
Femtosecond Time-resolved Ultraviolet Absorption
Spectra of All-trans retinal in Hexane
Wavelength / nm
SVD Analysis of the Femtosecond Time-resolved Ultraviolet
Absorption Spectra of All-trans-retinal in Hexane
Trans to Cis Isomerization via the S2 state
S3
S2
S1
7 ps
T1
S0
O
All-trans
9-cis
O
Photoisomerization Pathways and Dynamics of Retinal Isomers
S3
S2
50 fs
50 fs
S1
700 fs
400 fs
34 ps
7 ps
32 ps
900 ps
T1
S0
h
h
5 ms
O
All-trans
9-cis
O
Picosecond Time-resolved 2-D CARS Spectroscopy with an
Optical Kerr Gating
Optical delay
Ti:sapphire
oscillator / regenerative
amplifier system
Streak
camera
Spectrograph
Filter
SHG
Sample
Kerr cell
Analyzer
Polarizer
Filter
Gating pulse waveplate
~800 nm
Excitation
pulse
~400 nm
ns Nd:YLF
& dye laser
Optical Kerr Gating
Analyzer: 0°
Detector
CARS signal: 90º
Actinic light: 90°
Kerr medium (CS2)
Gate pulse: 45º
1: 90°
2: 90°
Optical Kerr Gated Picosecond CARS
Spectroscopy
Picosecond Time-resolved CARS Spectra of
Photoexcited All-trans Retinal in Ethanol : Simulation
K. Ishii and H. Hamaguchi, Chem. Phys. Lett, 367, 672 (2003).
First Observation of the key intermediate S2
S0
S2
S0+T1
S3
Very fast vibrational dephasing
S1
h
Large band width of the C=C band (100 cm-1)
T1
Dynamic polarization model of isomerization
S0
trans
S2
P*
P0
“perpendicular”
S0
cis
S0の減少
0
S２の生成、消滅
S0の回復
Cis体の生成
Ｔ１の生成
S3
h
S1
T1
S0
trans
S2
P*
・S2の振動スペクトル測定に初めて成功
・C=C伸縮バンドの顕著な広幅化(100cm-1)
異性化反応の動的分極理論と符合
P0
“perpendicular”
S0
cis
動的分極
Time-resolved Spectroscopies Look at Photoisomerization of
Retinal
S3
Fs UV-VIS
Ps CARS
S2
S1
10ps CARS
T1
Ns Raman
S0
Ns IR
O
All-trans
9-cis
O
Dynamic Polarization Model of Isomerization
Hamaguchi, Iwata, CPL 208, 465 (1993).
Deckert, Iwata, Hamaguchi, J. Photochem. Photobiol. 102, 35 (1996).
Iwata, Ozawa, Hamaguchi, JCP 106, 3614 (2002).
W1
W2
kiso= W1P(T)
Isomerization
kiso=Aexp(Arrhenius formula
E/RT) :
E=3.5 kcal mol-1 (fluorecsence lifetime)
kiso=W1P(T): Dynamic Polarization Model
E=3.5~3.7 kcal mol-1 (Raman band shape)
A new view on isomerization has come out of picosecond Raman spectroscopy !
Dynamic Polarization Model for the Retinal
Photoisomerization
Why are 13-cis and 9-cis selected?
7
9
11
13
15
O
hyperconjugation
7
9
11
13
15
O
hyperconjugation
7
9
11
13
15
O
014
Absolute Temperature Determination
with Stokes/anti-Stokes Raman spectroscopy
Temperature
at the laser focal spot?
Stokes/anti-Stokes Raman Scattering
Boltzmann factor
|v=1>
|v=0>
Stokes
antiStokes
Off-resonance Raman scattering
Sensitivity Calibration with Standard Light
Accuracy of
Sensitivity Calibration
Accuracy of the
Standard Intensity
Rotational Raman spectra as primary intensity standard
Previous study [1]
Sensitivity calibration with D2
D2[1]
This study
Sensitivity calibration with N2
-200 ~ +200 cm-1, 40 lines
Suitable for low-frequency region
[1] H. Hamaguchi, I. Harada, T. Shimanouchi, Chem. Lett. 1974, 12, 1405-1410.
Calculated Raman Cross Section Ratios of N2
1.0
cross-section ratio
0.8
0.6
cross-section
0.4
Intensity
Standard
0.2
0.0
5
10
Initial J
15
20
Low Frequency Raman Microspectrometer
Sample
Beam
sampler
Halogen lamp
Objective (x20
NA0.45)
Nd:YVO4
Laser (532 nm)
Long pass
filter
Polarizer
Spectrometer
f=50 cm
1800 gr/mm
Pinhole
(75 um)
Raman
scattering
Dichroic
mirror
Optical
image
CCD
Brag Notch filters
Intensity / a.u.
Rotational Raman Spectrum of N2
0
200
100
0
-100
Raman shift / cm
-200
-1
532 nm, 20 mW, x 20 Objective,
exposure: 30 min, resolution: 1.3 cm-1
Background (glass, air) was subtracted
Trace Naphthalene Melting
Sample
Thermocouple
(on the stage)
Peltier
heat/cool stage
Naphthalene
Mp. 353 K (80 °C)
532 nm, 4 mW, x 20 Objective
Exposure: 0.1 sec
Cycle: 0.22 sec / spectrum
Heat speed: 20 K / min
(on the heat stage)
Low-frequency Raman Spectrum of Naphthalene
Temperature determination
(-30 to -170 cm-1)
solid
532 nm, 4 mW, x 20 Objective,
exposure: 80 sec
Unusual Thermal Behavior before Melting
420
(a)
(b)
400
380
Temperature / K
192.7 s
Solid
360
m.p.
191.4 s
340
Liquid
320
> 50
K
300
100 μm
Heating
280
0
0) at r.t.
(< 0 s)
50
174.6 s
100
Heat time / sec
2)
plateau
1)
(50~120
increasing s)
to m.p.
Local
(0~50 s)
150
3)
fluctuation
(120 ~ 192 s)
200
400
200
0
Raman shift / cm -1
4) melting
(192.7 s~)
temperature fluctuation just before melting?
-200