The Reflection of Beams of the Alkali Metals from Crystals

Beams of lithium, potassium, and caesium were reflected from crystals of sodium chloride and lithium fluoride, as a means of studying the wave nature of these atoms. Incident angles from 2° to 60° were investigated. Although one one-hundredth percent of specular reflection could have been detected, no trace of such a reflection or of diffraction was found. The measured angular distribution of reflected atoms followed closely the cosine law. Apparatus, and the detecting device depending on positive ion emission by which this sensitivity of measurement was obtained, are described.