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 fi lm of Cr2O3(111) has been studied using 193 nm (6.4 eV) laser light. T he velocity flux distributions of the desorbing neutral CO in its grou nd electronic state were recorded quantum state specifically by making use of a (1 + 1') REMPI (resonance enhanced multiphoton ionization) t echnique. Single rovibrational states of the desorbing CO could be sel ected by using the (B1SIMGA+ <-- X1SIGMA+) transition in the VUV at al most-equal-to 115 nm for the first excitation step of the REMPI proces s. Excellent resolution was obtained in contrast to the most commonly used (2 + 1) REMPI process for the same intermediate state. The veloci ty 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.