Magnetic Deflection Method for Angular Distribution of Electrons Scattered by Gas Molecules

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Abstract
A method is given for evaluating the scattering coefficient for electrons colliding with gas molecules, if the electrons both before and after collision describe circular paths in a uniform magnetic field. As in previous methods an electron gun and a receiver are needed. The axis about which the gun may be rotated is parallel to the receiver slits and lies some distance from their common plane on a perpendicular thereto through the center of the first slit. The second slit with Faraday collector can be set at such distances from the first slit as to collect only electrons that have lost a definite energy on collision. The chief advantage over previous methods used for angular distribution study is that, since all electronic paths are circular, the angular distribution may be studied up to 180° scattering angle. The fact that the collector may be set for electrons of definite energy allows both elastic and inelastic collisions of slow electrons to be studied. Typical experimental curves are given which show the variation with angle of the scattering coefficient in mercury vapor for 80 and 30 volt electrons. The scattering angles cover the range from 20° to 180°. These results are compared with those of previous observers over that portion of this range which they studied. An application of the method to the inelastic collisions of 23 volt-electrons in mercury vapor is included.