INTERPRETATION OF THE 2-PHOTON, LASER-ASSISTED REACTIONS OF XENON WITH CL2, F2, AND CLF AND KRYPTON WITH F2

The excitation spectra and the transition rates (absorption cross sections) for the two-photon, laser-assisted reactions between Xe/Cl2, Xe/CIF, Xe/F2, and Kr/F2 pairs have been measured for modest pressures and 300 K. For these conditions the photoassisted reactions occur with approximately equal concentrations of bound van der Waals molecules and free pairs. The shapes of the Xe/Cl2, Xe/ClF, and Kr/F2 excitation spectra are similar, and the maximum in the spectrum is associated with the transition originating from pairs located near the minimum of the van der Waals potential and terminating on the reactive ionic potential surface. The vertical electron affinities of Cl2, ClF, and F2 are 1.0, 0.48, and 0.52 eV, respectively, according to this model. The widths of the excitation spectra reflect the gradients on the reactive ionic potentials. The Xe/F2 excitation spectrum is significantly broader than the excitation spectra for Xe/Cl2, Xe/ClF, and Kr/F2; this additional breadth is attributed to weak covalent bonding between Xe and F2 in the lower potential.