Use of Lead Sulphide Cells in Infra-red Spectroscopy

Abstract

THE photoconductive properties of lead sulphide when irradiated by wave-lengths between 1 and 3.5 µ were first utilized as a means of detecting infra-red radiation during the War by the Germans. In the later stages, lead sulphide detector cells were developed by the Admiralty¹ and in the United States², for within their range of operation they are far superior to any other detector in speed and sensitivity. The purpose of the present note is to indicate their possibilities as a tool in infra-red spectroscopy, and to describe some of our results in applying them to the attainment of high resolving power in the near infra-red region of the spectrum. The cells used by us were made at the Admiralty Research Laboratory by the evaporation process, and were cooled to a temperature of about – 78° C. by a mixture of solid carbon dioxide and acetone.