Chemiluminescent channels in reactions of Ba(1P1) with water, alcohols, and ethers

Abstract

The present paper investigates chemiluminescence in reactions of excited barium atoms (6s6p 1P1) with water and a series of alcohols and ethers. The electronically excited product molecule from the reaction with H2O (and D2O) is BaOH (and BaOD) in the A 2Π, A′ 2Δ, and B 2Σ levels. The product molecule is always Ba–ORx in reactions with alcohols ROH, whatever the size of the alcohol (methanol to butanol), and whatever its class (primary to tertiary). By comparison, no chemiluminescence was observed when the reactant was dimethyl and diallyl ether although allowed energetically. The nature of the product molecules in reaction with alcohols, and the absence of reaction with ethers that were found here are remarkably close to what was found by Davis et al. (submitted to J. Chem. Phys.) for the formation of ground state products in reactions of Ba(6s5d 1D2) with water, methanol, and dimethyl ether. The present work thus allows us to extend the model of Davis et al. for the reactivity of Ba(6s5d 1D2) as a powerful and general description of the reactivity of electronically excited barium atoms—the close approach of excited barium to water or alkyl alcohol molecules induces migration of the H atom that is bonded to oxygen. The reaction and the nature of the reaction product is determined by the departure of this H atom. The present paper also provides as side results determination of the Ba–OCH3 binding energy 3.8±0.1 eV, and spectroscopic information on several barium monoalkoxides.