Influence of solvents on the relaxation times of polymethine dyes in the picosecond range

An investigation was made of the dependence of the relaxation time r of the excited states of fourteen polymethine dyes with an absorption maximum near 1.06 μ on the nature of the solvent. The measurements were made by the direct method of picosecond flash photolysis. It was established that a choice of a suitable solvent could alter the value of the relaxation time τ by a factor of 1.5–5. A study of the dyes in various solvents made it possible to select materials for passive switches with relaxation times in the range from 2 to 130 psec.