Investigations on the spectrum of selenium. III.—Extension of Se III

Abstract

In the second of these contributions dealing with investigations on the successive spectra of selenium, evidence was obtained that the spectrum of Se III consists of singlets and triplets, and nearly all the terms corresponding to the deepest 4 p and the higher 5 s , 4 d , 5 p and s p 3 states were discovered, The present work is an extension of the identification of the predicted terms, particularly those arising from the still higher states 6 s and 5 d ; it also gives the results of a further investigation of the spectrum in the infra-red region. It was pointed out in part II that many of the lines due to the transition 4 d → 5 p must be situated in the infra-red above λ 6700, and that their wave-lengths could be exactly calculated from the known values of the terms. the spectrum in this region has accordingly been investigated with a Hilger Constant Deviation spectrograph. the source employed was the usual condensed discharge through a capillary tube excited by a ½ K. W. transformer. To photograph this region, krypto- and neo-cyanine plates were used, after hypersensitizing them in a bath of ammonia. Exposures extended over a period of 8 to 10 hours. The lines of the iron are served as standards for the measurements of the plates. measurement of tire plates.