Resonant Desorption from Clean and Carbon-Covered Alkali Halide Surfaces: State-Specific Detection by REMPI

Abstract

Desorption of NO from multilayer systems condensed on NaC1(100) as well as on C-films evaporated onto NaCl(100) was induced by resonant excitation of the symmetric stretch vibration υ1 of the NO cis-dimer with the frequency doubled radiation of a CO2 laser. On C-film-NaC1(100), additional non-resonant desorption was observed at lower condensate coverages (≈16 monolayers). Translational temperatures as derived from the time-of-flight distributions of the desorbed NO monomers are higher than or equal to the calculated maxima of the laser-induced surface temperatures. State-selective detection of desorbed NO molecules by resonance enhanced multi-photon ionization (REMPI) indicates rotational temperatures of 190 ± 20 K at corresponding desorbate translational temperatures of 120 K.