State-Selective Angular and Velocity Distributions of Associatively Desorbing CuF Molecules Determined by CCD Imaging

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 1998-11, Vol.102 (47), p.9327-9333
• Main Authors: Li, X, Wach, Th, Wanner, J, Kompa, K. L
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp980794s

The present contribution focuses on a new method of determining state-selective angular and velocity distributions of molecules desorbing from surfaces. It is based on the Doppler-resolved CCD imaging technique, i.e., exciting the molecules with an actively stabilized ring dye laser and imaging the fluorescence by a CCD camera. To analyze the two-dimensional images, a closed form mathematical procedure is used. The technique is applied to associatively desorbing CuF molecules in the reaction of molecular fluorine with copper surfaces. For all rovibrational CuF product levels investigated, the desorbing molecules exhibit a cos n θ, n = 1, distribution. Assuming that the velocity distributions of the desorbing CuF molecules are Maxwellian, the fitted translational temperatures are equal to the surface temperature within the error limits, proving an indirect reaction mechanism in agreement with previously determined internal state distributions [Bracker, A.; Jakob, P.; Näher, U.; Rüdiger, M.; Sugawara, K.; Wanner, J. Can. J. Chem. 1994, 72 (J. C. Polanyi Special Issue), 643].