The Absorption Spectrum of Tin Vapor in the Ultraviolet

Spectrum of tin.—(1) Arc spectrum. The spectrum of a 25 ampere arc was measured between 2170 and 1950A and 12 new lines observed. (2) Absorption spectrum of tin vapor, 6000 to 2000A. The tin was heated in a small carbon tube to about 1600°C and 53 absorption lines were observed, of which 38 are new. (3) Frequency differences. The results in general support the table of frequency differences given by McLennan, Young and McLay, lines from the normal state ${\mathrm{X}}_6$ and ${\mathrm{X}}_5$ showing strong absorption, those from ${\mathrm{X}}_4$ medium absorption, those from ${\mathrm{X}}_2$ only faint absorption and those from ${\mathrm{X}}_{\mathrm{i}}$ no absorption. A new table containing some changes and additions is given, using a different notation, which includes nearly all the arc lines. While the numerical relationships of the energy diagram are now well known, the nature of the terms involved has not yet been determined.