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(2P3/2) 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*(2P1/2) and the anisotropy parameter β to demonstrate the effect of photoabsorption caused by the z(1) state, which supports a recent experimental analysis.
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