UV photodissociation dynamics of CH2I2 molecule

Photodissociation dynamics of CH2I2 moleculae was investigated at different wavelengths of 277 to 305nm by an ion imaging spectrometer operated under optimal conditions for velocity mapping, where the ions were generated from (2 + 1) resonance-enhanced ionization (REMPI) of the photofragments I(P-2(3/2)) and I* (P-2(1/2)) at the same wavelength as that of the photolysis UV laser. The released kinetic energies and the angular distributions of both fragments at different photolysis wavelengths were derived from the three-dimensional velocity images. It was found that the photofragment of CH2I radical was highly excited. About 80% of the total released energy deposits into internal freedom. This fact can be explained by the impulse model. A remarkable difference between the kinetic energy distributions of I(P-2(3/2)) and I* (P-2(1/2)) was found. The dissociation mechanism of the formation of both I(P-2(3/2)) and I* (P-2(1/2)) fragments is discussed in terms of anisotropy parameter and energy partition. The kinetic energy distributions of the I(P-2(3/2)) and I* (P-2(1/2)) fragments are determined by the adiabatic and nonadiabatic dissociation processes in the electronically excited states of CH2I2