The formation of OH(A 2Σ+) from H2O in a longitudinal discharge

The production of OH molecules in the A 2Σ+ state by a discharge in a glass tube containing either H2O or H2O–rare gas mixtures was examined in a pressure range of about 1–10 mbar. The population density of A 2Σ+ OH molecules was determined to be in the order of 1013 cm−3. The formation of excited OH molecules is mainly due to electron impact dissociation of H2O.