Differential cross sections at [Formula Presented] and [Formula Presented] for electron-impact excitation of the [Formula Presented] [Formula Presented] state of [Formula Presented]

Abstract

Relative differential cross sections at forward and backward angles for excitation of the E [Formula Presented] state of [Formula Presented] have been measured in the resonant, near threshold energy region. Measurements are performed by using a double trochoidal electron spectrometer and are calibrated on the absolute scale by simultaneous measurements of this process and vibrational excitation of the ground state of [Formula Presented] via [Formula Presented] resonance. The contributions at [Formula Presented] and [Formula Presented] are separated by electron beam modulation and time-of-flight detection of scattered electrons. Obtained results confirm directly theoretical predictions of the symmetry of angular distribution of scattered electrons from [Formula Presented] resonance. 5555 2002 The American Physical Society.