The Spectra of Phosphorus. Part I. The Spectra of Neutral and Singly Ionized Phosphorus

Abstract

Investigation of the discharge emitted by a Geissler tube containing phosphorus vapor has resulted in the revision and extension of previous work on P I and P II. Twenty-two new terms classifying thirty-six lines of P I have been located. These lines also appear in a 25-ampere carbon arc containing calcium phosphide. The ionization potential is lowered tentatively from 11.1 to 10.9 volts and reasons are given for believing that this last value is still a few tenths of a volt too high. Term separations are in good agreement with values calculated by the method of Goudsmit and Humphreys. Isoelectronic sequences with S II, Cl III, and A IV indicate that some changes in S II classifications are necessary. Fifty-two new terms have been located in P II. These classify 194 lines in both the Schumann and visible regions of the spectrum. Nearly all of the expected singlet terms have been found. More than twenty intersystem combinations allow the singlet and triplet sequences to be located accurately with respect to one another. The P II ionization potential is 19.56 volts which is lower than the previously accepted value.