Direct High-Resolution Determination of the Singlet–Triplet Splitting in NH Using Stimulated Emission Pumping

A completely resolved spectrum of the strongly forbidden NH (a1Δ → X3Σ−) transition is observed. The NH radicals in the excited a1Δ state are exclusively generated in a Nd:YAG laser photolysis of hydrazoic acid at a wavelength of 266 nm. The NH (a1Δ → X3Σ−) intercombination transition around 794 nm...

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Bibliographic Details
Published in:Journal of molecular spectroscopy 1999-11, Vol.198 (1), p.115-122
Main Authors: Rinnenthal, Jan Leo, Gericke, Karl-Heinz
Format: Article
Language:English
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Summary:A completely resolved spectrum of the strongly forbidden NH (a1Δ → X3Σ−) transition is observed. The NH radicals in the excited a1Δ state are exclusively generated in a Nd:YAG laser photolysis of hydrazoic acid at a wavelength of 266 nm. The NH (a1Δ → X3Σ−) intercombination transition around 794 nm is used to produce NH (X3Σ−) applying the stimulated emission pumping technique. The ground state radicals are detected by laser-induced fluorescence (LIF). The energy splitting between the NH (X3Σ−, v = 0, J = 1, N = 0) state and the NH (a1Δ, v = 0, J = 2) state is determined with an accuracy of 0.1 cm−1 to ΔE = 12 687.865 cm−1. In addition, the radiative lifetime τ of the NH (a1Δ → X3Σ−) transition was estimated by a determination of the saturation intensity to be τ ≈ 12.5 s.
ISSN:0022-2852
1096-083X
DOI:10.1006/jmsp.1999.7947