Direct Observation of the Rate for Cis→Trans and Trans→Cis Photoisomerization of Stilbene with Picosecond Laser Photolysis
Direct Observation of the Rate for Cis→Trans and Trans→Cis Photoisomerization of Stilbene with Picosecond Laser Photolysis
复制标题
皮秒激光光解直接观察二苯乙烯的顺式→反式和反式→顺式光异构化速率
DOI：
--
复制
发表时间：
1982
期刊：
影响因子：
--
通讯作者：
K. Yoshihara
中科院分区：
文献类型：
--
作者：
M. Sumitani;K. Yoshihara
利用一种新研制的皮秒激光光解监测光源，在紫外区测量了二苯乙烯在溶液中的顺式→反式和反式→顺式光异构化反应速率。在295 K下，反式→顺式异构化在己烷中的速率常数为1.2×1010 s−1。反式二苯乙烯的S1态的荧光衰减速率常数具有相同的值。因此，S1态的衰变是速率限制步骤，并且中间垂直态（1p）的寿命必须非常短。顺式→反式异构化非常快，受激顺式异构体的半衰期小于几皮秒。这些观察结果强烈表明，异构化反应进行通过单重激发态的潜在的表面。
The rates for direct cis→trans and trans→cis photoisomerizations of stilbene in solution were measured with a newly developed monitor light source for picosecond laser photolysis in the UV region. The rate constant of the trans→cis isomerization is 1.2×1010 s−1 in hexane at 295 K. The fluorescence decay rate constant of the S1 state of trans-stilbene has the same value. Thus, the decay of the S1 state is the rate limiting step and the lifetime of an intermediate perpendicular state (1p) has to be very short. The cis→trans isomerization is very fast and the half life of the excited cis-isomer is less than a few picosecond. These observations strongly indicate that the isomerization reaction proceeds through the potential surface of the singlet excited states.