Observations of Population Inversion between theΛ-Doublet States of OH

Abstract
Inverted population distribution between Λ-doublet states of OH produced in the reaction H + NO2 → OH + NO has been observed in a beam maser and in a molecular-beam electric-resonance spectrometer. The observed inversions are of the order of 4-6% for the Π322, J=32, 52, 72, and the Π122, J=12 states, and less than 1% for the Π122, J=32, 52, 72, and 92 states.