Direct translation-to-vibrational energy transfer of HCl on gold: Measurement of absolute vibrational excitation probabilities

✍ Scribed by Qin Ran; Daniel Matsiev; Daniel J. Auerbach; Alec M. Wodtke

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 474 KB
• Volume: 258
• Category: Article
• ISSN: 0168-583X
• DOI: 10.1016/j.nimb.2006.12.077

✦ Synopsis

Vibrational excitation of HCl molecules (m = 0 ! 1) has been observed when HCl molecular beams at energies of 0.59-1.37 eV are scattered from a Au(1 1 1) surface at low surface temperature (T s = 273 K). The incident and scattered HCl is probed state-selectively using 2 + 1 REMPI. The vibrational excitation probability depends strongly on incidence kinetic energy, E i , exhibiting a threshold near $E i = 0.57 eV. We measured the absolute vibrational excitation probability which varies from 10 À6 to 10 À5 over this energy range, 1-2 orders of magnitude higher than the thermal equilibrium expectation value. The magnitude of the excitation probability, the near specular angular distributions of the scattered m = 1 molecules and the dramatic narrowing of the angular distribution near threshold are all consistent with a direct translation to vibration (T-V) mechanical energy transfer mechanism.