open access

https://hdl.handle.net/2115/13165

Hot-atom mechanism in photodesorption of molecular oxygen from a stepped platinum (113) surface

英語

1998-06-22

American Institute of Physics

The Journal of Chemical Physics

108(24)

10231-10238

The photodesorption of oxygen admolecules was studied on a stepped Pt(113) = (s)2(111) × (001) surface with 193 nm irradiation at 110 K. Multidirectional desorptions were found to collimate at ±12–20° and ±45–49° off the surface normal and also along the surface normal in a plane along the trough. The first component is always dominant, and the weak second component only appears at higher oxygen coverages. The normally directed desorption is not significant. The translational energy of desorbing O2 peaks around 15–20° and 50°, confirming the inclined desorptions. It is proposed that these inclined components are due to the desorption induced by the impact of oxygen admolecules with hot oxygen atoms from the photodissociation of adsorbed molecular oxygen, emitted along the trough. A simple cosine distribution was found to fit the thermal desorption from oxygen admolecules and also the recombinative desorption of oxygen adatoms. The 193 nm irradiation also produces additional, less tightly bound oxygen adatoms, which yield a desorption component collimated at 15° from the surface normal in the step-down direction

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Copyright © 1998 American Institute of Physics

0021-9606