Proposed secondary wavelength standards and line classifications in thorium spectra between 0.9 and 3 m

A. Giacchetti, J. Blaise, C.H. Corliss, R. Zalubas
1974 Journal of Research of the National Bureau of Standards Section A Physics and Chemistry  
The spectrum of thorium as emitted by an electrodeless lamp has been recorded by Connes and collaborators by means of Fourier Transform Spectroscopy in the region 0.9 to 3 μm. Of the 3100 lines observed, about 1900 are classified as transitions in the energy level system of Th i and 412 in Th ii. Since the average deviation between the observed and calculated wave numbers is less than 0.002 cm-1, the observed wavelengths are suitable for use as standard wavelengths.
doi:10.6028/jres.078a.015 pmid:32189782 pmcid:PMC6753049 fatcat:76n5ksovs5cqjk5d26otinx47e