Some Photoelectric Properties of Mercury Films

Abstract

Films of very pure mercury were deposited slowly in a high vacuum on an oxidized iron plate maintained at liquid air temperature. As each film increased in thickness, the photoelectric current excited by each of the mercury arc lines 253 7A, 2653A and 2700A increased from zero to a maximum value and then decreased to a final constant value. In each case the threshold wave-length at the time of maximum sensitivity was ca. 2750A. Its final value, that for a thick layer of mercury, was 2730 ± 15A; this did not change even when the mercury was allowed to melt, thus confirming a previous conclusion that the theshold wave-lengths for solid and liquid mercury are the same. There was no indication of a large shift in threshold wave-length at any time during the formation of the films.