Electron loss of CH- and CH2- induced by interactions with N2 and O2 at keV energies

Relative electron detachment cross sections for the projectiles CH- and CH2- colliding with N-2 and O-2 target gases were measured. Two different methods to measure the cross sections were used, the signal growth rate and the beam attenuation. The cross sections measured with the beam attenuation technique were higher than those measured with the signal growth rate method. An analysis based on the differences of the cross sections measured with the two methods showed consistency with the time dependent processes of metastable auto-detaching state populations undergoing decay as a function of its time of flight. These metastable processes seem to be target dependent. When the target was O-2, a decaying process characterized by a lifetime of the order of 0.40 +/- 0.16 ms was found. For the case of the N-2 as a target, it was not possible to derive a characteristic lifetime. (C) 2021 Elsevier B.V. All rights reserved.