An investigation of the SO(X3Σ-) molecule by multiphoton ionization spectroscopy

Abstract

Rydberg states of the SO molecule, in the region 62 500–67 500 cm-1 above the neutral ground state, have been studied using both (3 + 1) and (2 + 1) resonance enhanced multiphoton ionization (MPI) spectroscopy. Band assignment has been assisted by recording spectra with both linearly and circularly polarized radiation, by simulation of rotational band contours and by calculating quantum defects for the observed Rydberg states. Transitions to four Rydberg states (the 3Δ(4pπ), 3Π(3dδ), 3Π(3dσ) and 3Φ(3dδ) states) have been observed corresponding to promotion of an electron from the outermost occupied π molecular orbital in SO(X3Σ-) to the 4pπ, 3dδ and 3dσ Rydberg orbitals. For each state, spectroscopic constants have been derived from the experimental spectra. A (2 + 2) MPI spectrum of a known valence state, the B3Σ-, υ′ = 8 state, has also been obtained.