Optical spectroscopic study of thermal-energy charge transfer between He+ and CO2

Abstract

The thermal-energy charge transfer between He+ and CO2 has been studied by optical spectroscopy in a flowing afterglow apparatus fitted with pulse modulation equipment. CO+ (A 2Π–X 2Σ+) emission from v′(vi:)=0 to v′(vi:)=11 has been identified in the 300–500 nm region. The excitation rate constant of CO+ (A) was evaluated by comparing the total emission intensity with that for N+2 (B−X) emission in He+/N2. The upper limit to the excitation rate constant for CO+ (A) represents only 1% of all CO+ produced in the He+/CO2 reaction. The CO+(A) vibrational population was approximately exponential corresponding to an effective vibrational temperature of 10 500±900 K. The long range resonant model for the He+/CO2 reaction is discussed in the light of recent information on the product distribution and the excited states of CO+2.