Eur. Phys. J. D 24, 327-330 (2003)
https://doi.org/10.1140/epjd/e2003-00185-6

Size dependent reaction kinetics of small gold clusters with carbon monoxide: Influence of internal degrees of freedom and carbonyl complex stability

¹ Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
² Abteilung für Oberflächenchemie und Katalyse, Universität Ulm, 89069 Ulm, Germany

Corresponding author: ^a tbernhar@physik.fu-berlin.de

Received: 10 September 2002
Published online: 3 July 2003

Abstract

The reactions of free gold clusters Au^-, Au, and Au with carbon monoxide are studied in an rf-octopole ion trap experiment at cryogenic temperatures. While Au^- is unreactive toward CO over the whole temperature range investigated, the two and three atom cluster anions show a maximum adsorption of two CO molecules at temperatures below 250 K. From time resolved trapping experiments the strongly cluster size dependent reaction kinetics are obtained and a distinct reaction mechanism is deduced. The size dependence of the measured rate coefficients reveals the preferred formation and particular stability of the carbonyl complex Au₃(CO). Through RRK analysis of the absolute termolecular rate coefficients we are able to estimate the binding energy of CO to Au and Au.