Eur. Phys. J. D (2016) 70: 44
https://doi.org/10.1140/epjd/e2016-60485-2

Regular Article

Experimental investigation of the hyperfine spectra of Pr I-lines: discovery of new fine structure energy levels of Pr I using LIF spectroscopy with medium angular momentum quantum number between 7/2 and 13/2^*

¹ Institut für Experimentalphysik, Technische Universität Graz, Petersgasse 16, 8010 Graz, Austria
² Department of Physics, University of Karachi, 75270 Karachi, Pakistan
³ Department of Physics, Islamia College Peshawar, Peshawar, Pakistan

^a e-mail: windholz@tugraz.at

Received: 26 August 2015
Received in final form: 15 October 2015
Published online: 3 March 2016

Abstract

We present 39 even and 60 odd parity newly discovered fine structure levels of Pr I with angular momentum quantum numbers J = 7 / 2, 9/2, 11/2 and 13/2. Spectral lines in the wavelength range of 4200 Å to 7500 Å were investigated experimentally using laser-induced fluorescence spectroscopy or optogalvanic spectroscopy. Free Pr atoms were produced in a hollow cathode discharge. A high resolution Fourier transform spectrum of Pr was used to extract excitation wavelengths. From an analysis of the recorded hyperfine patterns, together with excitation and fluorescence wavelengths, we were able to find the unknown levels involved in the formation of the investigated lines. More than 500 spectral lines could be classified by the new levels.