Time-sliced ion imaging study of I2 and I2+ photolysis at 532 nm

Photodissociation of I2 and I2+ at 532.10 nm was studied using VUV photoionization/time-sliced velocity map imaging. The dissociation energies D0 of I2(X 1sigma g+) and I2(X 2pi 1/2g) were found to be 12,416 +/- 48 and 16,439 +/- 48 cm(-1), respectively. Absorption of 532.10 nm mainly corresponds to the excitation of I2(X 1sigma g+) to the 1pi(1u) and/or A3pi(1u) states, and the excitation of I2+(X 2pi 1/2g) to the A2pi 1/2u state, with a small fraction to the A2pi 3/2u and 4sigma u+ states. A method for accurate calibration of magnification factor of ion imaging system was presented. The improvement of energy resolution for large ionization volume experiments, like the crossed molecular beam and one-photon VUV photoionization experiments, was discussed.