New high-resolution studies of the 5p spectrum of Ba

Abstract

New high-resolution measurements of the 5p photoabsorption spectrum of Ba I are reported. The spectral dispersion is fifteen times higher than in the earlier investigation of the same spectrum performed in the laboratory and enables the authors to extend and improve the classification of the complex structure into overlapping Rydberg series. The wavelength calibration was also improved with respect to earlier work by superposing the photoabsorption spectra of He and Ne, which contain many sharp and accurately known transitions, thereby achieving identical illumination of the grating for both the spectrum under investigation and the calibration lines. The continuum source was provided by the 500 MeV electron accelerator in Bonn.