DEPENDENCE OF RADIATIONLESS RELAXATION IN ACRIDINE ON SOLVENT USING PICOSECOND SPECTROSCOPY

We have studied by means of picosecond spectroscopy the solvent dependence of internal conversion, intersystem crossing, and quantum yield of intersystem crossing of acridine in hexane, acetonitrile, isopropanol, and ethanol by following the growth rate of the Tn ←T1 transient absorption. Solvent dependence of the measured lifetime of the lowest excited singlet and the quantum yield of intersystem crossing on solvent strongly indicates that the 1n π*-1ππ* vibronic interaction, through a distortion of the lowest excited singlet state, is responsible for the unusual solvent dependent fluorescence behavior of this molecule. © 1978 American Institute of Physics.