Stable Compositions and Structures of Copper Oxide Cluster Cations Cu n O m + (n = 2-8) Studied by Ion Mobility Mass Spectrometry.

Abstract

Stable compositions and structures of copper oxide cluster cations have been studied by ion mobility mass spectrometry (IMMS) and density functional theory calculations. Cluster ions of the series CunOm+ were predominantly observed with n:m ≈ 2:1 in the mass spectrum. Collision cross sections (CCSs) of the cluster ions with n:m ≈ 2:1, determined by IMMS, were found to increase monotonically with cluster size. In addition, the CCSs of CunOn+ and CunOn–1+ (n = 2–8) were examined, and stepwise increases were observed for CunOn–1+ series. These cluster structures were assigned by comparison of the CCSs obtained via the IMMS experiment with theoretical orientation-averaged CCSs of optimized structures.