Photodissociation spectroscopy of Ca+–CO2

Abstract

Electronic spectra are observed for the metal cation complex Ca+–CO2, using resonance-enhanced photodissociation spectroscopy. The complexes are produced in a laser vaporization/supersonic expansion source, size selected and excited on resonance, and the mass-analyzed product is measured in a time-of-flight mass spectrometer. Both Ca+ and CaO+ dissociation channels are observed to have sharp resonances. Spectra from two isotopomers, the 40Ca+ and 44Ca+ species, are recorded and analyzed. Transitions from the X 2Σ+(v″=0) ground vibronic state to several vibrational levels in the D 2Πr excited electronic state are measured. The structure of the complex is confirmed to be linear by the presence of prominent spin–orbit multiplets. Spectroscopic constants for the 40Ca+–CO2 complex are determined: ν00=22 099.1 cm−1, Aso′=136.3 cm−1, ωe′=258.9 cm−1, and ωexe′=4.23 cm−1.