Table of Contents
Laser Chemistry
Volume 4 (1984), Issue 1-6, Pages 121-128

Picosecond Laser Study of Thioindigoid Dyes Photoisomerization

Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow region, Chernogolovka 142432, Russia

Received 16 February 1983; Accepted 10 May 1983

Copyright © 1984 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The transient species in the transcis photoisomerization of the perinaphto–thioindigoid dye were identified by picosecond laser spectroscopy in the time domain 10 ps–5 ns. An excitation of the trans isomer with a 6 ps, 528 nm pulse to the singlet state S1 (the peak of SnS1 absorption at 700 nm) results in the intersystem crossing S1T1 (the peak of TnT1 absorption at 730 nm) with the quantum yield of 0.7 and rate constant (1.4 ± 0.3)· 109s1. An excitation of the cis isomer results also in the intersystem crossing (the peak of Tn> ← T1 absorption at 670 nm) with the rate constant (3.7 ± 1.2)· 1010s1. The triplet mechanism of the photoisomerization in the both directions is proposed.