Single-collision caging of dissociating I2: wave packet calculations and simulation of femtosecond spectra

Based on recent experimental results on caging of I2 by collisions with rare gas atoms at room temperature [Wan et al, J. Chem. Phys. 106 (1997) 4353], wave packet simulations of Ar atoms colliding with I2 excited above the B-state dissociation limit by an ultrashort laser pulse, are presented. With the dependence on the initial orientation and the collision partners of the final vibrational state distribution of caged I2, full time-dependent simulations of the pump–probe experiments performed by Wan et al. for different Ar pressures were conducted. The excellent agreement between theory and experiment confirms the single-collision caging mechanism of Wan et al.