Effects of coadsorbed O2 on hydrogen ortho-para conversion on Ag surfaces
Abstract
Ortho-para (o-p) conversion of H2 and para-ortho (p-o) conversion of D2 were investigated on a Ag surface coadsorbed with O2 by resonance-enhanced multiphoton ionization combined with photostimulated desorption. Compared with a bare Ag surface, both H2 o-p conversion and D2 p-o conversion were accelerated on O2 -covered surfaces, and the conversion time was found to decrease with increasing O2 coverage. In order to analyze the conversion kinetics, Monte Carlo simulations taking account of hydrogen diffusion on the surfaces were performed and compared with the experimental data. The conversion time of H2 and D2 in the vicinity of adsorbed O2 was estimated to be 8.3 and 53.4 s, respectively. The isotope dependence of the conversion is discussed.
- Publication:
-
Physical Review B
- Pub Date:
- February 2009
- DOI:
- 10.1103/PhysRevB.79.085408
- Bibcode:
- 2009PhRvB..79h5408N
- Keywords:
-
- 82.65.+r;
- 68.43.-h;
- 82.20.Bc;
- 82.37.Vb;
- Surface and interface chemistry;
- heterogeneous catalysis at surfaces;
- Chemisorption/physisorption: adsorbates on surfaces;
- State selected dynamics and product distribution;
- Single molecule photochemistry