Gas Phase LIF Study of theb¹Σ⁺(b0⁺) ↔X³Σ^-(X₁0⁺,X₂1) Transition of NI

Author： Shestakov O. Gielen R. Setzer K.D. Fink E.H.

ISSN： 0022-2852

Source： Journal of Molecular Spectroscopy, Vol.192, Iss.1, 1998-11, pp. : 139-147

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Abstract

First gas phase spectra of the nitrogen monoiodide radical NI are reported. Theb¹Σ⁺(b0⁺) ↔X³Σ^-(X₁0⁺,X₂1) transition of NI has been studied by laser-induced fluorescence measurements. Ground state NI radicals were generated in a fast-flow system by reaction of microwave-discharged nitrogen with iodine vapor. Vibrational levelsv= 0, 1, and 2 of theb¹Σ⁺state were excited with a pulsed dye laser. Rotational and vibrational constants of theX³Σ^-andb¹Σ⁺states were deduced from analysis of high-resolution excitation spectra. Time-resolved measurements of the fluorescence decay and measurements of relative line and band intensities allowed determination of the radiative lifetime of thebstate, of band transition probabilities, and of the ratio of transition moments μ₀/μ₁for theb0⁺→X₁0⁺andb0⁺→X₂1 subtransitions. Comparison of calculated and experimental line intensities and FC factors shows that treatment of theX³Σ^-state in terms of a Hund's case (a) formalism is preferable to use of a case (c) formalism.