The band spectra of silicon fluoride

Abstract

This investigation of the band spectra of silicon fluoride originated in an attempt to produce the band spectra of boron fluoride. The latter would be of considerable interest in view of the close similarity which should exist between the BF and the CO molecule, and of the fact that our knowledge of the band spectra of CO is very extensive. We have made several attempts to obtain the boron fluoride spectra free from silicon fluoride, but without success. The boron fluoride is broken up by the discharge and the free fluorine attacks the silica in the glass. In order to interpret properly the plates obtained, it was necessary to know the systems due to silicon fluoride, and an examination of the literature revealed the fact that very little is known of the band spectra of this compound. Porlezza has examined the spectrum produced by admitting SiF 4 into a discharge tube, using a three-metre grating having 10,000 lines to the inch. He studied the violet end of the spectrum chiefly and records wave-lengths of about 60 heads in the region λλ 5475-3870. Some of these have been related in empirical formulæ: these are obviously some of the sequences of Table I. Dufour has examined the Zeeman effect on some of these bands, but apart from this work very little appears to be known about the band spectra of silicon fluoride.