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 Cu (n) O (m) (+) 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 Cu (n) O (n) (+) and Cu (n) O (n-1) (+) (n = 2-8) were examined, and stepwise increases were observed for Cu (n) O (n-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.