UV LASER-INDUCED DESORPTION OF CO FROM CR2O3(111) - A FULLY QUANTUM STATE-RESOLVED MAPPING OF THE DESORBING SPECIES

The laser-induced desorption of CO adsorbed on an epitaxially grown film of Cr2O3(111) has been studied using 193 nm (6.4 eV) laser light. The velocity flux distributions of the desorbing neutral CO in its ground electronic state were recorded quantum state specifically by making use of a (1 + 1') REMPI (resonance enhanced multiphoton ionization) technique. Single rovibrational states of the desorbing CO could be selected by using the (B1SIMGA+ <-- X1SIGMA+) transition in the VUV at almost-equal-to 115 nm for the first excitation step of the REMPI process. Excellent resolution was obtained in contrast to the most commonly used (2 + 1) REMPI process for the same intermediate state. The velocity flux distributions were bimodal for upsilon'' = 0 and monomodal for upsilon'' = 1. The high desorption cross section of (3.5 +/- 1) x 10(-17) cm2 is typical for the desorption from oxide surfaces.