Laser-induced thermal desorption of NO from a cryogenic C1NO film. Evidence for desorption barrier from time-of-flight distributions
✍ Scribed by Changlong Ning; Josef Pfab
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 674 KB
- Volume
- 223
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The dynamics of the 193 nm laser-induced thermal desorption of NO monomer from an irradiated ClNO film held at 80 K has been studied using state-resolved laser-induced fluorescence of NO. The rotational and electronic (spin-orbit) populations of the desorbed NO( v=O) deduced from LIF excitation spectra are described well by a Boltzmann distribution with a temperature close to that of the film. Translational distributions with an asymmetric and forward peaked shape with a sharp onset were found and explained by a small desorption barrier of 27 f 5 meV. The velocity distributions were only found to be Maxwellian provided this activation energy for desorption is included in the usual expression for a Maxwell-Boltzmann distribution of desorbate velocities. Both the internal and translational distributions support the conclusion that the desorption of cold NO(v=O) proceeds by a thermal desorption mechanism.