The Reflection of Positive Rays by A Platinum Surface

Intensity, energy and directional distribution of ${\mathrm{Li}}^{+}$ and ${\mathrm{K}}^{+}$ ions reflected from platinum.—In studying the reflections of positive rays by a platinum surface an apparatus similar to a spectrometer was set up in a good vacuum. A beam of lithium ions accelerated through a known $P.\mathrm{}D$. impinged upon a platinum reflector. The intensity, energy and direction of the reflected beam were measured by means of a rotating collector. Providing the reflector were "clean," i.e. white hot or cold but a few seconds, a considerable reflection was observed at certain angles. The angle of reflection was approximately specular but varied slightly with the accelerating voltage. The percentage reflected depended markedly upon the accelerating voltage. The maximum occurred approximately at 48 volts where approximately 75 percent were reflected. The reflected beam consisted of ions which had lost the major portion of their energy. Using a beam of potassium positive rays, approximately the same type of results was obtained.