Spark spectra of bismuth, Bi III and Bi II

Term schemes for Bi III and Bi II were established by the authors in 1930. A few terms in each spectrum were found to have large hyperfine structure separations. Later Fisher and Goudsmit carried out an experimental and theoretical study of the hyperfine structures of these spectra which, in general, confirmed our term analyses. In the present communication we report the results of a more extended investigation of the term structures of these two spectra, and in addition give further information on their hyperfine structures. New experimental data were obtained by photographing spectra of bismuth from 1000 A. to 10,000 A. For the extreme ultra-violet region a vacuum spectrograph, designed and set up by one of us (M. F. C.), was used. Equipped with a 2-metre N. P. L. grating, this spectrograph has an average dispersion of 8.75 A. per millimetre. A hilger E1 quartz spectrograph was employed to investigate the near ultra-violet and visible regions; and a Hilger constant deviation spectrograph for the infra-red.