Resonance fluorescence spectra of 80Se2

Abstract

The gas-phase resonance fluorescence spectra of ⁸⁰Se₂ excited by the argon ion laser lines at 4880 and 4765 Å consist of long series of Stokes and anti-Stokes R, P doublets. Measurements of these spectra combined with a detailed study of the absorption spectrum in this wavelength region show that the 4880 Å line excites R(38) in the 1–14 band, the 4765 Å line R(15) in the 0–12 band, both in the Ω= 1_u–Ω= 1_g component of the B³Σ^–_u–X³Σ^–_g transition. Improved vibrational and rotational constants for X1_g(³Σ^–_g) are derived, as follows: G= 387.156 (v+½)–0.964 (v+½)²; F₂: B_v= 0.090 16 – 2.98 × 10^–4(v+½); F₃: B_v= 0.090 22 – 3.01 × 10^–4(v+½). The uncorrected relative intensities are in qualitative agreement with calculated Franck-Condon factors. In these series the qualitative variation of intensity with v″ is determined by the shape of the vibrational wavefunction in the upper state.