Observation of the adsorption and desorption kinetics of weakly bound CO on Si(001)-c(4×2) by means of scanning tunneling microscopy

• Published in: Surface science 2014-09, Vol.627, p.29-33
• Main Authors: Momose, T., Ohno, S., Kitajima, T., Suzuki, T., Tanaka, M.
• Format: Article
• Language: English
• Subjects: Adsorption; Carbon monoxide; CO molecule; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Desorption; Exact sciences and technology; Exposure; Formations; Islands; Physics; Reaction kinetics; Scanning tunneling microscopy; Si surface; Surface chemistry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2014.04.008

The weak adsorption state of CO molecules on a Si(001)-c(4×2) surface at the temperature of 75K has been investigated by means of scanning tunneling microscopy (STM). Lateral expansion of CO-adsorbed islands and preferential formation of a weakly adsorbed state near the CO adsorbed islands were directly observed with STM at low CO exposure. We found that the weakly adsorbed CO is desorbed from the surface when CO exposure is stopped. At high CO exposure, we observed multilayered CO islands, which disappeared after cessation of CO exposure. [Display omitted] •We discovered that two types of weakly bound CO exist on Si(001)-c(4x2) only during CO exposure and at low coverage.•We discovered that multilayer CO islands are formed on Si(001)-c(4x2) only during CO exposure and at high coverage.•The life time of metastable CO species is evaluated to be about 70-80s at low coverage and about 100s at high coverage.•We constructed the reaction models for metastable CO species both at low and high coverage regime.