A femtosecond-time-scale photolysis study of vapor-phase GaCl

Time-resolved absorption spectra are recorded for Ga atoms produced by the photolytic action of 300 fs, 248.5 nm laser pulses on gas-phase GaCl molecules. Photodissociation of GaCl at 248.5 nm produces both ground-state ( 2P1/2) and spin-orbit-excited (2P 1/2) Ga atoms, resulting in strong transient-absorption features at 403.3 and 417.2 nm, respectively. The experimental spectra are analyzed to obtain the kinetic energy of the photofragments, which is estimated to be ≃0.08 eV for both channels. The analysis suggests that the dissociation limits are (1) Ga 2P1/2+Cl* 2P 1/2 for the 403.3 nm channel; and (2) Ga* 2P 3/2+Cl 2P3/2 for the 417.2 nm channel. From these results, a new estimate for the dissociation energy of GaCl is obtained: D00=4.80±0.03 eV. © 1993 American Institute of Physics.