THE EFFECT OF TEMPERATURE ON PHOTOPROCESSES IN ACETONE SOLUTIONS OF CR(NH3)2(NCS)4-

The photolysis yields and emission lifetimes for solutions of Cr(NH3)2(NCS)4- in fluid acetone have been recorded as a function of temperature in the range - 93 to 10-degrees-C. The 2E levels are quenched by 02 and the relative contributions of the fast and slow photoreactions have been determined by comparing the photolysis yields in deaerated and 02 saturated solutions. The quantum yield of the prompt process is 0.02 and is temperature independent. The thermal enhancement of the slow photolysis correlates with depopulation of 2E and the results are consistent with back-intersystem crossing as the pathway for this process.