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CIS-STILBENE PHOTOCHEMISTRY - DIRECT OBSERVATION OF PRODUCT FORMATION AND RELAXATION THROUGH 2-COLOR UV PUMP-PROBE RAMAN-SPECTROSCOPY
被引:44
作者:
PHILLIPS, DL
[1
]
RODIER, JM
[1
]
MYERS, AB
[1
]
机构:
[1] UNIV ROCHESTER,DEPT CHEM,ROCHESTER,NY 14627
关键词:
D O I:
10.1016/0301-0104(93)80224-W
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
The formation of hot trans-stilbene by photoisomerization of cis-stilbene, and its subsequent vibrational cooling, have been monitored by picosecond two-color UV pump-probe anti-Stokes Raman spectroscopy. Pairs of pump (295 nm) and probe (278 nm) pulses at a 500 Hz repetition rate interrogate flowing samples of cis-stilbene in cyclohexane or methanol, and the anti-Stokes Raman scattering due mainly to the trans-stilbene product is detected. Hot ground-state trans-stilbene appears promptly within our 10 ps experimental time resolution, and the anti-Stokes intensity decays with a time constant of 39 +/- 10 ps in cyclohexane and 17 +/- 5 ps in methanol. The decay of the anti-Stokes intensity is accompanied by a shift of the C=C stretching vibrations by about 20 cm-1 to higher frequencies. The question of whether or not the initial vibrational distribution is statistical is addressed, but the present data do not allow firm conclusions to be drawn.
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页码:1 / 12
页数:12
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