High resolution daytime photoelectron energy spectra from AE‐E

Abstract
The daytime photoelectron energy spectrum has been measured at altitudes above 154 km by the photoelectron spectrometer experiment on the Atmosphere Explorer‐E satellite. Much higher energy resolution spectra than previous AE‐C results have been obtained. Below 200 km, well resolved peaks are observed in the spectrum corresponding to production of O+ and N2+ in various electronic states from photoionization of N2 and O by solar He II (304A) radiation. Vibration‐rotation excitation of N2 by inelastic electron scattering is observed at 2.5 eV. The features due to nitrogen disappear from the spectrum at altitudes above 200 km.