Theoretical study on angular momentum polarization parameters, branching ratios, and anisotropy parameters of chlorine atoms from Photodissociation of Iodine Monochloride

Low-lying excited state potential energy curves (PECs), nonadiabatic coupling terms, and transition dipole moments of ICl have been obtained by a spin-orbit configuration interaction method. The angular momentum polarization parameters of photofragments can be calculated from these properties of the molecule. The first-rank parameter Im[a₁⁽¹⁾(//,)] of the ground state photofragment Cl(²P_3/2) in the first absorption band (490-560 nm) is very sensitive to the PECs of the low-lying excited states, especially the A(1) and B(0⁺) states. The phase part of the calculated parameter Im[a₁⁽¹⁾(//,)] agrees well with experiment. We further clarify the characteristics of avoided crossing between the X(0⁺) and B(0⁺) states. We calculated the product fraction of Cl*(²P_1/2) and the anisotropy parameter β to demonstrate the effect of photoabsorption caused by the z(1) state, which supports a recent experimental analysis.