A study of the spark spectra of arsenic

The spectra of arsenic have been photographed from the infra-red to the vacuum ultraviolet with a 21 foot grating, a 2 metre vacuum grating, a Littrow prism spectrograph, and a constant deviation spectrograph using an elect-rodeless discharge source. The wave lengths of 1500 lines in the region 550 to 9300 A have been measured relative to Iron standards. Some 300 of these were previously classified, chiefly in As I and As II. Another 500 have now been assigned to the various spark spectra, leaving less than 10% of the observed intensity unaccounted for. The chief extension has been made in As II with more than 50 new energy levels being established. The resulting analyses have been critically examined in terms of the intermediate coupling relations proposed by M.H. Johnson* and the atomic energy relations due to Bacher and Goudsmit+. These relations permit the evaluation of important radial integrals of Slater, and the study for the first time of how these integrals changes both in the various spark spectra of an element and with the successive series members within a given spectrum For unperturbed configurations these theories are found to be satisfactory. *M.H. Johnson, Jr. Phys. Rev. 38, l628, 1931; 39, 197, 1932 + R.F. Bacher and S.A. Goudsmit, Phys. Rev. 46 948; 1934Science, Faculty ofPhysics and Astronomy, Department ofGraduat