Precursor dynamics in dissociative hydrogen adsorption on W (100)

✍ Scribed by David A. Butler; Brian E. Hayden; John D. Jones

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 699 KB
• Volume: 217
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)e1395-w

✦ Synopsis

A study of the dynamics of dissociative adsorption on H2 of W ( 100) has been carried out using a supersonic molecular beam source. For beam energies in the range 200-l 3 meV, a 30% increase in the initial sticking probability so is observed with decreasing translational energy. At low beam energies, a complex incident angular dependence of s0 is also observed. The sticking probability s exhibits a linear decrease with hydrogen coverage at higher energies, however in the lower energy regime a more complex coverage dependence is exhibited, manifested in an initial independence, or increase, in s with increasing coverage. This behaviour is also associated with the contribution of an indirect route to dissociation at lower energies, in addition to a direct channel which predominates above = 150 meV. The value of so at a beam energy of 13 meV, where the contribution of the indirect channel should be greatest, appears to be independent of surface temperature within the accessible range 150 c T.(K) i 370. We suggest that the probability that the precursor will go on to dissociate rather than desorb depends on the surface structure.