Photoelectron spectroscopy of (CO2)n− revisited: core switching in the 2 ⩽ n ⩽ 16 range

Photoelectron spectra of (CO2)n− have been measured a photon energy of 4.66 eV, and the vertical detachment energy (VDE) determined as a function of the cluster size, 2 ⩽ n ⩽ 16. The n-dependence of the VDE shows sharp discontinuities between n = 6 and 7, and between n = 13 and 14, indicating that CO2− and C2O4− are formed as the core anions in (CO2)7− and (CO2)14− and vice versa when ‘core switching’ results from the formation of geometrically favored structures.