Spectrum of the hydroxyl radical

Abstract

The B 2 Σ + → A 2 Σ + and C 2 Σ + → A 2 Σ + systems of OH and OD were photographed at high resolution. The apparent dissociation energy D 0 (A 2 Σ + ) is calculated to be (18 847 ± 15) cm −1 for OH and (19 263 ± 15) cm −1 for OD. An upper limit to D 0 (X 2 Π 3/2 ) of OH is deduced to be (35 420 ± 15) cm −1 . Evidence for a potential maximum in the B 2 Σ + state, which is about 100 cm −1 larger than that in the A 2 Σ + state, is presented.The broadening of the rotational lines in several bands of both systems has established a strong predissociation of the A 2 Σ + state near ν = 5 in OH. The lifetime of these predissociated levels is ≈10 −11 s. A definite identification of the predissociating state has not been possible.Newly-discovered vibrational levels in the C 2 Σ + state have led to the following constants, in cm −1 , of the OH radical in the C 2 Σ + state:[Formula: see text]Rotational constants and spin splitting constants in the A 2 Σ + and B 2 Σ + states, more accurate than previously available, are presented.