Very low rate constants of bimolecular CO adsorption on anionic gold clusters: Implications for catalytic activity

Absolute bimolecular rate constants for radiative stabilization of CO on gold cluster anions are measured by Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry, employing a sequence of reaction gas pulses to acquire sufficient product intensities of these exceedingly inefficient reactions. While some of the observed reactivity patterns seem to be in agreement with the jellium model if CO is viewed as a two electron donor, it cannot provide an explanation for some other observations, for instance for the secondary reactions of Au-10(-) and Au-11(-). Interesting cooperative effects are observed in conjunction with O-2, which is present as a trace component of the reaction gas. No evidence is found for catalytic CO2 formation on the clusters.