Laser induced desorption of small alcohols from Ag(111) by resonant vibrational excitation
| Autor: | H. A. Donsig, D. Ranier, K.‐C. Chan, L. S. Brown |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 11:2084-2089 |
| ISSN: | 1520-8559 0734-2101 |
| Popis: | Laser induced photodesorption of methanol, ethanol, and 1‐propanol from films condensed on a Ag(111) crystal by resonant excitation of the O–H stretching vibration has been examined, and preliminary results are presented. The desorption yield depends exponentially on the laser pulse energy. For a particular pulse energy, the desorption yield decreased with increasing molecular weight of the alcohol, which is consistent with the variation of the heats of adsorption for these molecules. For methanol, a strong dependence of the desorption yield on the film morphology was observed as well, with crystalline films producing desorption signals as much as an order of magnitude greater than amorphous films of the same thickness. Time‐of‐flight measurements have been used to determine the kinetic energy of the desorbed molecules, and it was found that this energy also depends on the laser pulse energy. For a fixed pulse energy, the observed kinetic energy increased with increasing molecular weight of the alcohol. All of these results are at least qualitatively consistent with a resonant heating mechanism for the photodesorption process. |
| Databáze: | OpenAIRE |
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