Observation of coherent excitation processes in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>e</mml:mi></mml:math>-H collisions

Abstract

In a measurement of emission of Balmer-$\ensuremath{\alpha}$ flux from atomic hydrogen or deuterium excited by electron impact in a crossed-beam experiment, a longitudinal electric field which enhances the Balmer-$\ensuremath{\alpha}$ flux by Stark-mixing components of like ${M}_{J}$ within the $n=3$ shell, does so asymmetrically depending on whether the field is applied parallel or antiparallel to the electron beam. The effect is attributed to coherent excitation of states of opposite parity.