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MIYASAKA Lab. Tetsuro KATAYAMA

Observation of Coherent molecular oscillation : Herzberg-Teller type Wave Packet Motion in Porphyrin J-aggregates. MIYASAKA Lab. Tetsuro KATAYAMA. Contents. Coherent molecular oscillation. Franck-Condon type Wave Packet Motion. Herzberg-Teller type Wave Packet Motion.

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MIYASAKA Lab. Tetsuro KATAYAMA

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  1. Observation of Coherent molecular oscillation : Herzberg-Teller type Wave Packet Motion in Porphyrin J-aggregates MIYASAKA Lab. Tetsuro KATAYAMA

  2. Contents Coherent molecular oscillation Franck-Condon type Wave Packet Motion Herzberg-Teller type Wave Packet Motion “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

  3. Introduction • 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) N. F. Scherer, et al., JCP,1993, 99, 153

  4. Coherent molecular oscillation • Pump-probe spectroscopy Pump A ⊿ Detector t 0 ･Photoinduced absorption Probe A ⊿ t 0 Sample τ Delay Time ･Photo-bleaching , stimulated emission Photoinduced (Transient) absorption　：　過渡吸収 Photo-bleaching ： ブリーチ Stimulated emission　：　誘導放出

  5. Franck-Condon type wave packet motion ･The curvature is the same. ･Equilibrium nuclear position is different. • Linear coupling assuming harmonic oscillator excited state ･Coherent oscillation of transientabsorption and stimulatedemission are observed Energy ground state ･Raman transitions causes wave packet motion in the ground state which can be observed in the photo-bleaching oscillate Nucleus separation Franck-Condon type wave packet motion ： フランクコンドン型波束運動 Equilibrium nuclear position ： 平衡核間距離 Raman transitions ： ラマン遷移

  6. 211 cm-1 420 cm-1 Overtone was observed at 526nm probe for iodine 580 nm pump 580 nm probe 580 nm pump 526 nm probe Overtone ： 倍音 N. F. Scherer, et al., JCP,1993, 99, 153

  7. Why was overtone observed ? • Typical Franck-Condon type wave packet motion 580 nm ,480 nm I2 excited state energy surfaces Turning point 524 nm ground state Center N. F. Scherer, et al., JCP,1993, 99, 153

  8. Theory • Herzberg-Teller type wave packet motion ･The curvature is the same. ･No displacement between the equilibrium position. ･Transition frequency do not depend on the wave packetposition. Energy μ+δμ μ-δμ ･In Herzberg-Teller type model . Transition dipole moment depends on the wave packet position μ constant Nucleus separation Herzberg-Teller type wave packet motion ： ヘルツベルグテラー型波束運動

  9. Two types of wave packet motion Franck-Condon type Herzberg-Teller type A ⊿ Wavelength Wavelength

  10. Experimental • SampleTetraphenylporphinetetrasulfonic acid ( TPPS4 ) • J-aggregate ～2nm J-aggregate ： Ｊ会合体 R. Rotomskis et al J. Phys. Chem.B,2004, 108, 2833

  11. AFM image of Macroscopic TPPS4 J-aggregates (Optical microscopy) (AFM image) AFM ： 原子間力顕微鏡法 Optical microscopy ： 光学顕微鏡 R. Rotomskis et al J. Phys. Chem.B,2004, 108, 2833

  12. Stationary absorption and fluorescence Stokes shift is very small(>20meV) H.Kano.et at.Journal of the Chinese Chemical Society, 2000, 47, 859

  13. Transient absorption spectrum Transient absorption 320fs Photo-bleaching and stimulated emission

  14. Probe wavelength dependence of the coherent oscillation Amplitude Reversed at～1.78eV Overtone wasn’t observed

  15. Resonance Raman spectrum It is attributed to out-of-plane ruffling mode ruffling mode

  16. Frequency dependence of the initial phase and amplitude Initial phase is constant It might not be Franck-Condon type Amplitude is reversed around 1.78eV(697nm)

  17. Oscillation was observed in the integrated signal Oscillation was also observed in the integrated signal from 1.65 to 1.91eV(752nm to 649nm) 247cm-1 It might not be Franck-Condon type

  18. Justification of Herzberg-Teller type

  19. 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.

  20. What is Window function ? : Window function vibration

  21. X-ray CrystallographyⅠ

  22. X-ray CrystallographyⅡ

  23. How know formation of j-aggregate? J-band

  24. Dynamic IntensityBorrowing -Vibronic coupling -Configration interaction

  25. Vibronic coupling • parity-forbidden • avibration of the molecule can destroy theInversion symmetry • The removal of the centre of symmetry gives rise to a vibronically allowed transition.

  26. Experimental • Setup Laser system

  27. Introduction • Pump-Probe Spectroscopy Transmittance Detection Pump Probe Sample Delay Time

  28. ･What is Window function ?

  29. J-aggregate

  30. Why is Stokes shift small ? • Frenkel exiciton : TPPS :Transition dipole moment

  31. Frenkel exiciton make a mode strong Atkins,D.L. et al ,J. Phys. Chem., 1996, 100, 14391

  32. Problem • Really was it observed ? E.A.Carson,et al.,J.phys.Chem.A2004,108,1489-1500

  33. Theory • Herzberg-Teller type +δμ －δμ μ+δμ μ μ μ

  34. Why does a wave packet form?

  35. Results ＆ Discussions • Stationary absorption The laser spectrum J-band (Monomer) (J-aggregate) T. Ogawa et al..Chemical Physics Letters ,2005,408 ,186

  36. Resonance Raman spectrum

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