Electron stimulated desorption from solid CO2 and a hydrogen containing CO2 matrix: A comparative study

Citation
L. Siller et al., Electron stimulated desorption from solid CO2 and a hydrogen containing CO2 matrix: A comparative study, J CHEM PHYS, 110(21), 1999, pp. 10554-10561
Citations number
41
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF CHEMICAL PHYSICS
ISSN journal
00219606 → ACNP
Volume
110
Issue
21
Year of publication
1999
Pages
10554 - 10561
Database
ISI
SICI code
0021-9606(19990601)110:21<10554:ESDFSC>2.0.ZU;2-B
Abstract
We have studied electron stimulated desorption of positive ions from simila r to 15 monolayer (ML) film of pure solid CO2 adsorbed on polycrystalline P t surface at similar to 40 K using incident electrons in the energy range 1 -31 eV. The positive ions O+, C+, CO+, CO2+, and O-2(+) were observed and t heir threshold energies are discussed. Hydrogenation of the CO2 film was fo und to reduce the O-2(+) production but the threshold remained the same as for the pure CO2 matrix. After hydrogenation of the CO2 matrix additional i ons-H+, H3O+, HCO+, and H2CO+-are observed. The formation of formaldehyde c ations (with a threshold energy of 17+/-1.5 eV) in the hydrogenated CO2 mat rix has been observed for the first time and is a product of electron stimu lated ion-molecule reactions, possibly via a process analogue to the so-cal led photosynthesis. These results could be relevant to a better understandi ng of the atmosphere of Mars. (C) 1999 American Institute of Physics. [S002 1-9606(99)70821-4].