Temperature dependence of the fluorescence lifetime and quantum yield of pseudoisocyanine monomers

Abstract

Fluorescence intensities and lifetimes of 1,1'-diethyl-2,2'-cyanine chloride (pseudoisocyanine) at 1.0 × 10 −2 M in glycerol have been measured in the temperature range 84–298 K. Comparison with previous results shows that the solution consists of dye monomers. Arrhenius plots yield two activation energies for internal conversion: 2247.7 and 334.7 cm −1. Fluorescence quantum yields, evaluated from measured lifetimes and τ o = 3.7ns, are between 2.6% (298 K) and 47.5% (84 K).