PHOTOINDUCED REACTIONS OF CH2I2 IN SOLUTION STUDIED BY THE ULTRAFAST TRANSIENT ABSORPTION-SPECTROSCOPY

We have studied the photo-induced reactions of CH2I2 upon excitation a t 268 nm in CH3CN by femtosecond transient absorption spectroscopy. Th e time profile of transients observed at 400 nm consists of three comp onents: fast rise (200 fs), fast decay (500 fs), and slow rise (7-13 p s). The first two components are independent of the solute concentrati on and are assigned to the photofragment CH2I radical. The slow rise b ecomes faster by increasing concentration and is assigned to the forma tion of a charge-transfer complex between the photofragment I and CH2I 2 in solute aggregate. This is followed by full electron transfer from CH2I2 to I forming CH2I2+.