Branching ratios and anisotropy parameters in ICl photolysis from 400 to 570 nm using slice imaging

Abstract

ICl photolysis in the visible region of the spectrum (400-570 nm) is studied using the slice imaging technique. The Cl((2)P(1/2))/Cl((2)P(3/2)) branching ratio between the I((2)P(3/2))+Cl((2)P(3/2)) and I((2)P(3/2))+Cl((2)P(1/2)) channels is extracted from the iodine photofragment images and it is found to range from 0 to 2.5, rising from 570 to 490 nm and dropping at higher photolysis energies. The I+Cl angular distribution exhibits a similar trend, changing from purely perpendicular at 570 nm to isotropic at 545 nm, fairly parallel at 490 nm and again perpendicular at 440 nm. Following previous work, we discuss these changes in light of avoided curve crossing and determine the crossing probability as a function of wavelength. The angular anisotropy parameter beta of the second channel ranges between 0.6 and 1.4.