UV photodissociation dynamics of CH2I2 molecule
紫外波段CH2I2分子的光解离动力学研究

Photodissociation dynamics of CH 2I 2 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( 2P 3/2) and I *( 2P 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 CH 2I 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( 2P 3/2) and I *( 2P 1/2) was found. The dissociation mechanism of the formation of both I( 2P 3/2) and I *( 2P 1/2) fragments is discussed in terms of anisotropy parameter and energy partition. The kinetic energy distributions of the I( 2P 3/2) and I *( 2P 1/2) fragments are determined by the adiabatic and nonadiabatic dissociation processes in the electronically excited states of CH 2I 2.