The description of an apparatus for selecting atoms of particular velocities from atomic and molecular rays is given. The theory of the action of the apparatus is outlined and the characteristics of expected spectrum-like images are discussed. An atomic ray on its way towards a chemically active target is conveyed through two vibrating slits at a distance D apart. The vibrations are controlled by the oscillating current of an electron tube. The emerging ray contains selected velocities. For very small ratios of the width w of vibration to the amplitude of the slit a, the selected velocities are determined by vn=2Df/n where f is the frequency of vibration and n=0, 1, 2, 3, etc. For larger w/a ratio a great number of velocity bands are obtained each embracing a range
When used in connection with the Gerlach and Stern magnetic moment analyzer, images should be obtained consisting of n pairs of lines, whose thickness is
An example for a hydrogen atom ray at 500° K is calculated.
© 1927 Optical Society of America
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