XVII.—The Ultra-Violet Emission Spectra of the Halogens

Abstract

Most of the work on the emission spectra of the halogens has been confined to the visible or near ultra-violet regions: but, in view of the characteristic chemical and photo-chemical properties of these elements, it has become increasingly important to make a general survey extending well into the ultra-violet. The emission spectra of chlorine and bromine in the visible and near ultra-violet up to about 370 µµ have been described by Eder and Valenta as consisting of lines, chiefly in the green and blue. For bromine, a continuous spectrum was also observed, starting at about 490 µµ; this rapidly falls off in intensity, but at about 420 µµ a second continuous band commences, extending with increasing intensity to the limit of their photograph about 370 µµ. Quite recently the investigation of the quartz ultra-violet region of chlorine has occupied several observers, chiefly from the physical point of view; Jevons has measured the ultra-violet line spectrum from 335 µµ to 207 µµ, and a communication on the same subject has appeared from Angerer.