1. Ultrafast Excited-State Isomerization Dynamics of 1,1‘-Diethyl-2,2‘-Cyanine Studied by Four-Wave Mixing Spectroscopy
Benjamin Dietzek, Niklas hristensson, Torbjörn Pascher, Tõnu Pullerits, and Arkady Yartsev
J. Phys. Chem. B, 2007, 111 (19), pp 5396–5404
Miyasaka Lab.
Masayasu Muramatsu

2. Contents Introduction Experimental method Results ＆ Discussion Summary
Photoinduced Isomerization
1122C　Excited-State bond-twisting motion
　Experimental method
Transient Absorption
TransientGrating
Three-pulse photon echo peak-shift
　Results ＆ Discussion
　Summary

3. Photoinduced Isomerization
Control
　pathway
　rate　.etc
eye sight
trans-stilbene
cis-stilbene
hn’
254nm hn
313nm hn
11-cis retinal
all-trans retinal
200fs
model system　vs 　biological system
　　　→function of the protein matrix

4. Excited-State bond-twisting motion
Methanol
538nm
523nm
500ps
trans-1122C
cis-1122C

5. DA = -log I I0 a → b a b DA A A a b a b Transient Absorption Probe
Pump
Transient species
Sample hn
a → b a b DA A A a b
Reference a b

6. Pulse participation Hole spectrum time Excited State Absorption （ESA）
Ground
State
Bleach
（GSB）
Stimulated
Emission
（SE）
Hole spectrum
time

7. Transient Grating （TG）
2pulse interference
１）　Thermal change
２）　Volume change
３）　Spectrum change
3pulse interference
n(t)：refracture index
k(t)：absorbance

8. Three-pulse photon echo peak-shift
τ≫0：decoherent　　　　　　　　 → 　no echo
T≫0：vanish diffraction fringe　 → 　no echo

9. Three-pulse photon echo peak-shift
Signal in
k3+k2-k1
direction
100fs
1ps
10ps
100ps

10. Transient Absorption Stimulated emission ESA:excited-state population
4.9ps
ESA:excited-state population
405nm
405nm(filled triangle)
573nm(open star)
700nm(open triangle)
850nm(open aquare)
1000nm(filled circle)

11. Transient Grating 548nm Rise:Stimulated Emission (dark state)
Viscosity, large
→Decay time, large
Rise:Stimulated Emission (dark state)
Decay:Internal Conversion

12. Transient Grating 530nm 495nm
495nm：no emission
　　→no rise

13. 3PEPS 548nm Rise:Stimulated Emission (another state)
viscosity
　large
　　↓
inhomogeneity
Rise:Stimulated Emission (another state)
The osillation pattern is insensitive to solvent
　 →　It is not related to torsion

14. 3PEPS 5ps~ Rise: cis isomer formation ?
methanol
propanol
Vibrational
Relaxation
548nm(red), 530nm(green), 495nm(blue)
5ps~ Rise: cis isomer formation ?
or Ultrafast Internal Conversion ?

15. Summary Transient Absorption Transient Grating 3PEPS
ESA(405nm): ~1ps(flat),τ=4.9ps(decay)
SE(548nm):~1ps(decay)→dark state
Transient Grating
wavelength dependent rise ← ESA
solvent dependent decay ← internal conversion
3PEPS
high viscosity
→high inhomogeneity
rise(495nm) →cis isomer?
1ps
4.9ps
500ps
538nm
523nm