The electronic spectrum of PrO. Energy linkages, rotational analysis, and hyperfine structure for systems XVII and XXI

Abstract

Doppler-limited laser excitation spectra for four bands of PrO have been recorded: System XvII 0-0, System XXI 0-0 and 0–1, and the 0-0 intercombination between the upper and lower states, respectively, of Systems XVII and XXI. First lines in R and P branches prove that Systems XVII and XXI are, respectively, Ω′ = 4.5 − Ω″ = 3.5 and Ω′ = Ω″ = 4.5. Hyperfine components are well resolved for all four excitation bands. Rotational and hyperfine constants are determined by least-squares fits of data from all four bands together. In addition, fluorescence spectra, recorded from various J′, v′ = 0 levels of the upper states of Systems XVII and XXI, reveal five new low-lying states. Principal constants (in cm−1) for nine Ω-states follow (1σ uncertainty in parentheses): StateTvBvd(hfs)Ω′ = 4.5 (System XXI)18 882.388 (2)0.353001 (18)0.12403 (71)Ω′ = 4.5 (System XVII)16 594.075 (1)0.353736 (20)0.12977 (67)Ω″ = 3.53 887.15 (16)0.35751 (28)—Ω″ = 3.52 931.66 (15)0.35712 (21)—Ω″ = 4.52 155.16 (30)0.36264 (67)—Ω″ = 5.52 099.16 (31)0.35079 (71)—Ω″ = 3.52 064.34 (13)0.35654 (20)—Ω″ = 4.5 (System XXI)217.383 (1)0.362134 (20)0.27744 (66)Ω″ = 3.5 (System XVII)0.00.360948 (16)−0.00809 (85)