SOLVATION DYNAMICS OF COUMARIN-153 IN MOLTEN-SALTS

Static and time-resolved fluorescence techniques are employed to measu re the solvation statics and dynamics of electronically excited coumar in 153 in several molten tetraalkylammonium salts. The solvation of co umarin 153 occurs on two time scales which are both dependent on the c ation size. The larger the cation size, the longer the relaxation time . For coumarin 153 in molten tetrabutylammonium hydrogen sulfate, the Stokes shift relaxation times are approximately 40 and 220 ps for the short and long component respectively. For coumarin 153 in molten tetr adodecylammonium perchlorate, the relaxation times are 200 and 2000 ps . The steady-state emission band position is strongly dependent on the molten salt cation size. The band maximum position for coumarin 153 i n molten tetrapropylammonium hydrogen sulfate is at 18 250 cm-1 (548 n m), while for tetradodecylammonium perchlorate the band maximum is at 20 120 cm-1 (497 nm).