Populations of BaO states in the Ba+N2O chemiluminescent flame using the BaO C 1Σ+ state as a probe

Abstract

The reaction Ba+N2O→BaO+N2 in the presence of argon buffer gas (25 μ) has been studied using laser induced fluorescence to probe the nonchemiluminescent states present. We have observed ground electronic state (X 1Σ+) vibrational levels from v″=7 to v″=32 by exciting them using a N2 laser pumped tunable dye laser to various vibrational levels of a highly excited electronic state (C 1Σ+) and observing the resulting ultraviolet fluorescence to low ground state vibrational levels (v″<12). Low ground state vibrational levels (v″=0–9) have also been observed by exciting the molecules to the A 1Σ+ state and observing vibrationally resolved visible fluorescence. We find the C 1Σ+ state to be highly perturbed, but still useful as a population probe for the X 1Σ+ state. We measure the C 1Σ+ radiative life time to be 25±10 nsec. The X 1Σ+ vibrational population from v″=5 out to v″=32 has a characteristic temperature of about 3600 °K. We find evidence of nonthermal population of v″=13–16. We also observed population in the A′1π and the a 3π states with v″=0–4. The implications of these results on the identity of the nonchemiluminescent precursor states in the Ba+N2O reaction are discussed.