The infra-red spectra of dysprosium, erbium and gadolinium in the 1.1 to 5.4 micron region*

The emission spectra of Dy, Er, and Gd are reported for the infra-red region 1.1 to 5.4 microns, 8940 to 1835 cm-1. Two sources, a water cooled hollow cathode and an electrodeless discharge lamp, were employed. The spectra were recorded using the National Solar Observatory McMath lm Fourier transform spectrometer (FTS) at Kitt Peak, AZ over the spectral region of 40 000 to 1817 cm-1. Improved frequencies are possible by calibration using argon lines and the frequencies of argon reported by Norlen1. The energy levels published2 in NSRDS-NBS 60 were used to calculate all possible transition energies. These energy values were then matched with the observed frequencies. The neutral (I) and singly ionized atom (II) frequencies were calculated and matched.