Photophysical properties of laser dyes: picosecond laser flash photolysis studies of Rhodamine 6G, Rhodamine B and Rhodamine 101

Abstract

The UV–VIS absorptive and emissive properties of three laser dyes, viz. Rhodamine 6G, Rhodamine B and Rhodamine 101, have been studied in ethanolic and methanolic solutions. Time-resolved methods were used to study the decay of the first excited singlet state of each dye. The absorptive properties of the lowest excited singlet states of Rhodamine 6G, Rhodamine B and Rhodamine 101 were generated using picosecond laser pulses. Values for the molar absorption coefficient for the S_nâ†� S₁ absorption process were measured, for each dye, by both comparative and complete-depletion methods. Values for the S₄â†� S₁ absorption process, in ethanol, were found to be 3.7 × 10⁴(452 nm), 4.4 × 10⁴(428 nm) and 4.3 × 10⁴(430 nm) dm³ mol^–1 cm^–1 for Rhodamine 101, Rhodamine 6G and Rhodamine B respectively with the corresponding values for the S₃â†� S₁ absorption process being measured as 7.7 × 10⁴(576 nm), 6.4 × 10⁴(532 nm) and 3.8 × 10⁴(566 nm) dm³ mol^–1 cm^–1. These results are compared and contrasted with available literature values.