Observation of the A2Σ+ ← X2Π Electronic Transition of NaO

Abstract

The gas-phase infrared spectrum of the A2Σ+ ← X2Π electronic transition of the NaO radical was observed for the first time utilizing tunable diode laser differential absorption spectroscopy; 109 lines were found within the region 2015−2095 cm-1 and 45 lines within 2654−2696 cm-1. The NaO radical was produced by reaction of sodium vapor with N2O in a fast flow tube and detected using an astigmatic Herriott multipass absorption cell combined with rapid sweep integration absorption signal processing. Simple kinetic studies were performed in order to differentiate the NaO radical features from precursor N2O lines. The NaO A2Σ+ ← X2Π vibronic band structure was modeled using ab initio calculations by Langhoff and co-workers; the simulated NaO band profile agrees reasonably well with that observed. A preliminary assignment of some observed lines and the resulting molecular constants are presented. Quantitative absorption strength measurements indicate that either absorption line strengths for this transition are significantly smaller than indicated by ab initio calculations or the Na + N2O reaction produces a significant fraction of NaO(A) state which resists collisional quenching under our experimental conditions.