On spectra associated with carbon

Abstract

It has been known for many years that, in addition to the line spectra due to the carbon atom, there are a number of band spectra associated with carbon and hydrogen, and carbon and oxygen, and the precise origin of these band spectra has in the past been the subject of many investigations. Of these band spectra the most familiar are the Swan spectrum and the Ångström bands. The former consists of a number of regular bands, degraded to the violet, with principal heads at λλ. 6188, 5635, 5165, 4737, 4382, each principal head being followed by a series of sub-heads, and is found practi­cally isolated in the flames of burning hydrocarbons. It also occurs in the blue cone at the base of the Bunsen burner, in the carbon arc, and under appropriate conditions in vacuum tubes. The Ångström bands, also degraded to the violet, with heads at λλ 6623, 6079, 5610, 5198, 4835, 4511, 4393, 4123, are a conspicuous feature in vacuum tubes containing carbon and oxygen, and are familiar as an impurity in tubes excited by uncondensed discharges when adequate precautions have not been taken to exclude the presence of carbon compounds. The CH bands, which were first studied in detail by Eder, and which are evidently associated with some compounds of carbon and hydrogen, are found in the base of the roaring Bunsen flame, and in vacuum tubes containing carbon and hydrogen. They constitute a complex group of bands with a principal head at λ4315 degraded to the violet, and have recently been identified by Newall, Baxandall, and Butler with the G line in the Fraunhofer spectrum.