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Abstract:
The UV-laser-induced desorption of CO from an epitaxially grown film of Cr2O3(0001) is reported using a (1 + 1′) REMPI (resonance enhanced multiphoton ionisation) detection technique via the B1Σ+ electronic state for the desorbing molecules to obtain information on single rovibrational states. The final state distributions at three different wavelengths (6.4, 5.0 and 3.5 eV) were almost identical showing bimodal velocity flux distributions for v″ = 0 and monomodal distributions for v″ = 1. The desorption cross-sections varied between (5.1 ± 1) × 10−18 cm2 at 3.5 eV and (3.5 ± 1) × 10−17 cm2 at 6.4 eV. The overall behaviour indicates that the excitation mechanism is due to a primary electronic excitation step within the substrate. Possible mechanisms are discussed.
