IDENTIFICATION OF RADIATIVE EMISSIONS RESULTING FROM ELECTRON RECOMBINATION OF O2H+ AND N2OH+ IONS

A flowing afterglow technique has been developed for distinguishing be tween radiations emitted from electron-ion recombination and those fro m other sources such as ion-neutral and neutral-neutral reactions. The technique utilizes a ps which rapidly attaches electrons to create co nditions where electron-ion recombination can or cannot occur. This ha s enabled experimental conditions to be established that maximize the photon emission rates without having to create a situation where only one reaction process contributes to the emission, which inherently res ults in substantially smaller signal levels. Such a technique allows e missions from optically weak transitions to be detected. The applicati on of the technique is illustrated for the the dissociative electron-i on recombinations of O2H+ and N2OH+ over the wavelength range 200-400 nm. From this study, the relative contributions of the vibrational lev els of the OH(A2SIGMA+) state to these spectra have been obtained, and in the case of N2OH+, the relative significance of the NH(A3PI(i)) ch annel to the OH(A2SIGMA+) channel has also been determined. The variat ion with attaching gas concentration of the intensity of a spectral fe ature due to recombination has also been shown to be very different fr om the variation observed in a feature due to other reactions.