Electronic excited state energy transfer,trapping by dimers and fluorescence quenching in concentrated dye solutions: Picosecond transient grating exp

Picosecond transient grating experiments are used to examine electronic excited state dynamics in concentrated dye solutions. A model based on radiationless excited state transport and trapping by dimers describes the phenomena responsible for fluorescence quenching. The trapping rate constant is found to have a cubic concentration dependence. Rhodamine 6G dimer lifetimes in glycerol and ethanol are 830 ps and <50 ps respectively. The difference arises due to the viscosity dependence of the dimer radiationless relaxation rate.