The A′2Δ state of ScO: Analysis of the A′2Δ (v = 3) ∼ A2Π (v = 1) perturbation

Abstract

Detailed information about the ScO A′2Δ state is obtained from analysis of the A2Π (v = 1) ∼ A′2Δ (v = 3) perturbation. The deperturbation analysis is based on 774 and 51 lines in the A2Π-X2Σ+ (1-0) and (1-1) bands, measured respectively to 0.006 and 0.010 cm−1 accuracy in fluorescence excitation spectra recorded with a single mode, continuous wave (cw) dye laser. One hundred and one “extra,” nominally A′2Δ, rotational levels are observed: 6.5 ≤ J ≤ 36.5 in 2Δ32 (the 2Δ32 ∼ 2Π32 crossing occurs near J = 31.5) and J = 64.5 in 2Δ52 (2Δ52 crosses 2Π32 near J = 64.5). The observed lines were assigned, fitted, and deperturbed by an iterative procedure utilizing a nonlinear least-squares fittoa 2Π ∼ 2Δ effective Hamiltonian matrix model. Deperturbed molecular constants and perturbation parameters are obtained for A2Π (v = 1) and A′2Δ (v = 3). Values obtained for previously unknown molecular constants include Be(A′2Δ) = 0.4815 cm−1 (re = 1.723 Å) and Av=3(A′2Δ) = 47.1 ± 0.3 cm−1. The fitted values for the spin-orbit and orbit-rotation perturbation parameters are used to estimate the 4p, 3d composition of the A2Π state within the context of a one-electron Sc2+O2− electronic structure model. The molecular constants and orbital character are compared against ab initio calculations.