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![Page 1: Observation of Coherent molecular oscillation : Herzberg-Teller type Wave Packet Motion in Porphyrin J-aggregates MIYASAKA Lab. Tetsuro KATAYAMA.](https://reader036.fdocuments.us/reader036/viewer/2022062304/56649d205503460f949f5687/html5/thumbnails/1.jpg)
Observation of Coherent molecular oscillation : Herzberg-Tell
er type Wave Packet Motion
in Porphyrin J-aggregates
MIYASAKA Lab.Tetsuro KATAYAMA
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Contents
“Observation of Herzberg - Teller-type Wave Packet Motion
in Porphyrin J-Aggregates Studied by Sub-5-fs Spectroscopy”
H. Kano, T. Saito,and T. Kobayashi . J. Phys. Chem. A, 2002, 106, 3445
Coherent molecular oscillation
Franck-Condon typeWave Packet Motion
Herzberg-Teller typeWave Packet Motion
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Introduction
N. F. Scherer, et al., JCP,1993, 99, 153
Coherent molecular oscillation observed by femtosecond transient spectroscopy
Coherent molecular oscillation : コヒーレントな分子振動Iodine : ヨウ素 (I2)
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Coherent molecular oscillation
Probe
Pump
Detector
Delay TimeSample
0
0 t
t
A
⊿
A
⊿
τ
・ Photoinduced absorption
・ Photo-bleaching , stimulated emission
Pump-probe spectroscopy
Photoinduced (Transient) absorption : 過渡吸収Stimulated emission : 誘導放出
Photo-bleaching : ブリーチ
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Franck-Condon type wave packet motion Linear coupling assuming harmonic oscillator
En
erg
y
Nucleus separation
・ The curvature is the same.・ Equilibrium nuclear position is different.・ Coherent oscillation of transient absorption and stimulated emission are observed
・ Raman transitions causes wave packet motion in the ground state which can be observed in the photo-bleaching
excitedstate
groundstate
Franck-Condon type wave packet motion : フランクコンドン型波束運動Raman transitions : ラマン遷移Equilibrium nuclear position : 平衡核
間距離
oscillate
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Overtone was observed at 526nm probe for iodine
580 nm pump580 nm probe
580 nm pump526 nm probe
211 cm-1
420 cm-1
Overtone : 倍音 N. F. Scherer, et al., JCP,1993, 99, 153
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Why was overtone observed ? Typical Franck-Condon type wave packet
motion
524 nm
Center
Turning point
580 nm ,480 nm
I2 excited state energy surfaces
ground state
N. F. Scherer, et al., JCP,1993, 99, 153
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Theory Herzberg-Teller type wave packet motion
En
erg
y
Nucleus separation
・ The curvature is the same. ・ No displacement between the equilibrium position.
・ Transition frequency do not depend on the wave packet position. ・ In Herzberg-Teller type model .
Transition dipole moment depends on the wave packet position
μ+δμ
μ
μ-δμ
Herzberg-Teller type wave packet motion : ヘルツベルグテラー型波束運動
constant
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Two types of wave packet motion
Wavelength Wavelength
⊿
Franck-Condon type
Herzberg-Teller type
A
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Experimental Sample Tetraphenylporphine tetrasulfonic acid
( TPPS4 )
~ 2nm
J-aggregate
R. Rotomskis et al J. Phys. Chem.B, 2004, 108, 2833
J-aggregate : J会合体
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AFM image of Macroscopic TPPS4 J-aggregates
AFM : 原子間力顕微鏡法
(AFM image) (Optical microscopy)
Optical microscopy : 光学顕微鏡 R. Rotomskis et al J. Phys. Chem.B, 2004, 108, 2833
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Stationary absorption and fluorescence
H.Kano.et at.Journal of the Chinese Chemical Society, 2000, 47, 859
Stokes shift is very small(>20meV)
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Transient absorption spectrum
Photo-bleaching andstimulated emission
Transient absorption
320fs
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Probe wavelength dependence of the coherent oscillation
Overtone wasn’t observed
AmplitudeReversed at ~ 1.78eV
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Resonance Raman spectrum
ruffling mode
It is attributed to out-of-plane ruffling mode
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Frequency dependence of the initial phase and amplitude
Initial phase is constant
Amplitude is reversed around 1.78eV(697nm)
It might not be Franck-Condon type
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Oscillation was observed in the integrated signal
Oscillation was also observed in the integrated signal from 1.65 to 1.91eV(752nmto 649nm)
It might not be Franck-Condon type
247cm-1
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Justification of Herzberg-Teller type
1 Stokes shift was small(>20meV)
2 Over tone wasn’t observed at any
wavelength
3Amplitude was reversed around 1.78eVbut phase was constant.
4Coherent oscillation was also observedfrom integrated signal
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Summary
The wave packet observed in the present study can be classified as a Herzberg-Teller type in contrast with the frequently studied conventional Franck-Condon type.
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vibration
: Window function
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X-ray Crystallography Ⅰ
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X-ray Crystallography Ⅱ
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How know formation of j-aggregate?
J-band
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Dynamic IntensityBorrowing
-Vibronic coupling
-Configration interaction
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Vibronic coupling parity-forbidden
a vibration of the molecule can destroy the Inversion symmetry
The removal of the centre of symmetry gives rise to a vibronically allowed transition.
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Experimental Setup
Laser system
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Introduction Pump-Probe Spectroscopy
Probe
Pump
TransmittanceDetection
Delay TimeSample
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・・ What is Window function ?What is Window function ?
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J-aggregate
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Why is Stokes shift small ? Frenkel exiciton
: TPPS
: Transition dipole moment
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Frenkel exiciton make a mode strong
Atkins,D.L. et al ,J. Phys. Chem., 1996, 100, 14391
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Problem Really was it observed ?
E.A.Carson,et al.,J.phys.Chem.A 2004,108,1489-1500
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Theory Herzberg-Teller type
μ
μ+δμ
- δμ+δμ
μμ
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Why does a wave packet form?
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Results & Discussions Stationary absorption
T. Ogawa et al..Chemical Physics Letters ,2005,408 ,186
J-band
(J-aggregate) (Monomer)
The laser spectrum
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Resonance Raman spectrum