Spectrum of the hydroxyl radical

The B²Σ⁺→A²Σ⁺ and C²Σ⁺→A²Σ⁺ systems of OH and OD were photographed at high resolution. The apparent dissociation energy D°(A²Σ⁺) is calculated to be (18847 ± 15) cm⁻¹ for OH and (19263 ± 15) cm⁻¹ for OD. An upper limit to D°(X²π₃/₂) OH is deduced to be (35420 ± 15) cm⁻¹. Evidence for a dispersion hump in the B(²Σ⁺) state which is about 100 cm⁻¹ larger than the hump in the A(²Σ⁺) state is presented. The broadening of the rotational lines in several bands of both systems has established a strong predissociation of the A(²Σ⁺) state near v = 5 in OH. The lifetime of these predissociated levels is ≈10⁻¹¹ seconds. A definite identification of the predissociating state has not been possible. Newly discovered vibrational levels in the C(²Σ⁺) state have led to the following constants, in cm⁻¹, of the OH radical in the C²Σ⁺ state Te = 89500 Be = 4.247 D° = 29418 ± 15 ∝e = 0.078 ωe = 1232.9 Ɣ(v=O) = 1.09 Ωeχe = 19.1 Ɣ(v=1) = 0.88 Rotational constants and spin splitting constants in the A(²Σ⁺) and B(²Σ⁺) states, more accurate than previously available are presented.Science, Faculty ofPhysics and Astronomy, Department ofGraduat