Abstract
Experimental investigations of Pr I spectral lines were performed by means of laser induced fluorescence spectroscopy, using a hollow cathode discharge lamp as source of free atoms. The wavelengths for the laser excitation were found by the help of a highly resolved Fourier transform spectrum. Altogether we excited 236 unclassified lines and analysed their hyperfine structure, which led, together with the measured wavelengths of the observed fluorescence lines, to the discovery of 32 new even parity and 38 odd parity fine structure energy levels. These levels allow to classify more than 670 spectral lines of Pr I. The wave number calibrated Fourier transform spectrum allowed us to determine the energies of most of these newly discovered levels with an uncertainty of 0.015 cm-1. Angular momenta, parity, and magnetic and electric hyperfine interaction constants (A and B) of the new levels were also determined.
Highlights
Praseodymium is a rare earth element belonging to the lanthanides group
We focused on searching for new fs levels of praseodymium and were able to discover a significant number of levels, some of which have already been published, see refs. (Uddin et al 2012a, Shamim, Siddiqui & Windholz 2011, Syed et al 2011, Uddin et al 2012b, Siddiqui, Shamim & Windholz 2014, Uddin et al 2012c, Uddin 2014, Gamper, Khan, Siddiqui & Windholz 2013, Siddiqui, Shamim & Windholz 2016, Uddin, Siddiqui, Tanweer, Jilani & Windholz 2015)
11549.602 cl Experimental investigation of the hyperfine structure of Pr I lines is reported in this paper
Summary
Praseodymium is a rare earth element belonging to the lanthanides group. Its atomic number is 59, and it has naturally occurring only one stable isotope 141Pr with nuclear spin quantum number I = 5/2. White (White 1929) investigated the wave number separation of hf structure components of 173 spectral lines He was the first in determining the nuclear spin quantum number of 141Pr. Since 1929 and over the span of five decades, several authors investigated the spectrum of praseodymium and discovered several electronic levels which were collected and published in 1978 (Martin, Zalubas & Hagan 1978). Her published (and not yet published) work is based on the study of the fine and hyperfine structures in the configurations 4f25d6s2 and 4f25d26s of neutral praseodymium In this work, she calculated the wave numbers for a large number of new fs levels and determined their hyperfine interaction constants.
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