An experimental and theoretical investigation of the radiative properties of the A 3Π state of NH

• Published in: Chemical physics letters 1987, Vol.138 (2), p.185-194
• Main Authors: Gustafsson, O., Kindvall, G., Larsson, M., Olsson, B.J., Sigray, P.
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Exact sciences and technology; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); Molecular properties and interactions with photons; Physics
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/0009-2614(87)80366-4

The experimental high-frequency deflection (HFD) technique and the theoretical complete active space SCF (CAS SCF) ab initio method have been used to investigate the radiative properties of the A 3Π state of NH. Fluorescence lifetimes of rotational fine-structure levels were measured for ν' = 0 and 1. These measurements gave a lifetime of τ (ν' = 0, N' = 1, F le)=453 ± 10 ns. Radiative lifetimes were calculated with the help of non-orthogonal CAS SCF wavefunctions and the result for ν = 0 was 408 ns. Small discrepancies between measured and calculated lifetimes are discussed in terms of a predissociation in the A 3Π state caused by the continuum of the X 3Σ − ground state. Model calculations suggest that these discrepancies can be removed if the nonradiative process A 3Π (bound)→ X 3Σ − (continuum) is taken into account.