Electronic spectroscopy of cations at reduced temperatures

Abstract

The application of the techniques of matrix-absorption, laser-excitation and laser-absorption spectroscopies of mass-selected ion beams to the study of small open-shell cations at reduced temperatures is described. The spectroscopic characterization of the B ⁴Σ^–_uâ†� X ⁴Σ^–_g transition of C⁺₂ was carried out first in a neon matrix, then at high-resolution using laser-excitation spectroscopy. Two-photon ion-absorption experiments which are being developed to characterize cations spectroscopically are demonstrated on N₂O⁺. The instrument used is a triple-quadrupole mass spectrometer designed to select primary ions, constrain them for photon absorption and to detect fragment ions.