Adsorption of intact methanol on Ru(0001)

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Abstract

Fourier transform infrared absorption spectroscopy has been used to study the adsorption of methanol on the clean Ru(0001) surface at T <= 80 K. Thereby, clear evidence for intact adsorption has been found. This observation contradicts previous studies which suggested an OH(OD) bond scission upon adsorption of methanol on Ru(0001), even at low temperatures, as well as partial recombinative desorption at higher T. Our conclusion is based on isotopic shifts of vibrational modes associated with the OH (OD) group of adsorbed CH3OH and CH3OD. Density functional theory (B3LYP) confirms these findings, as it reproduces the observed frequencies and isotopic shifts well. Additional support for our conclusion of nondissociative adsorption of methanol on Ru(0001) is provided by thermal desorption experiments of CH3OH coadsorbed with deuterium on Ru(0001). We find that CH3OD formation is clearly below detection threshold, while desorption of CH3OH is quite prominent; a recombinative desorption of dissociated methanol and hydrogen/deuterium as suggested in the literature is therefore discarded. At very low coverages and temperatures the presence of isolated methanol molecules or dimers is suggested. With increasing density or by annealing a low coverage methanol layer, hydrogen bonding leads to cluster formation, as evidenced by an intensity loss of those vibrational modes affected by hydrogen bonds, in conjunction with a substantial line broadening. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3151674]

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  • Atom and Molecular Physics and Optics
Original languageEnglish
Article number224703
JournalJournal of Chemical Physics
Volume130
Issue number22
Publication statusPublished - 2009
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Chemical Physics (S) (011001060)