Optical Excitation of Phosphorus Vapour

Abstract

ON illuminating the vapour of phosphorus by the light of various sparks, we obtained a fluorescent emission in the region 3500–1900 A. The vapour was contained in an evacuated and sealed quartz tube into which a quantity of carefully dried white phosphorus distilled in vacuo was previously introduced. The temperature and pressure of the vapour could be varied independently by an oven and a water bath. In order to obtain the fluorescence, heating of the vapour up to 600°–700° C. was found to be necessary, the vapour pressure being kept low (c. 0.1 mm.). The phosphorus molecules, which consist normally of four atoms (P4), dissociate under these conditions into diatomic molecules (P2) to an appreciable amount.