PHOTOPHYSICAL PROPERTIES OF LASER-DYES - PICOSECOND LASER FLASH-PHOTOLYSIS STUDIES OF RHODAMINE-6G, RHODAMINE-B AND RHODAMINE-101

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(n) <-- S1 absorption process were measured, for each dye, by both comparative and complete-depletion methods. Values for the S4 <-- S1 absorption process, in ethanol, were found to be 3.7 x 10(4) (452 nm), 4.4 x 10(4) (428 nm) and 4.3 x 10(4) (430 nm) dm3 mol-1 cm-1 for Rhodamine 101, Rhodamine 6G and Rhodamine B respectively with the corresponding values for the S3 <-- S1 absorption process being measured as 7.7 x 10(4) (576 nm), 6.4 x 10(4) (532 nm) and 3.8 x 10(4) (566 nm) dm3 mol-1 cm-1. These results are compared and contrasted with available literature values.