EGAS41 - Swansea University

41 st EGAS CP 157 Gdańsk 2009
New even parity levels in neutral lanthanum
B. Furmann, D. Stefańska
Chair of Quantum Engineering and Metrology, Faculty of Technical Physics, Poznań
University of Technology, ul. Nieszawska 13B, 60-965 Poznań, Poland
∗ Corresponding author: boguslaw.furmann@put.poznan.pl,
Electronic levels system in lanthanum atom becomes very complicated at energies above
30000 cm −1 . In order to describe this levels system, a configurations basis including more
than ten configurations has to be considered. Because of lack of experimental results
concerning g J factors and hyperfine structure constants for many electronic levels, their
assignment to individual configurations is often doubtful and attempt of application of
ab initio calculated radial integrals yields considerable discrepancies between the calculated
and the experimental results.
In this situation the only solution seems to be measurement of hyperfine structure for
a great number of known levels, as well as determination of energies, J quantum numbers
and hyperfine structure constants for new, previously not observed electronic levels. In
our recent works [1, 2] we published experimental results obtained for more than 100 levels
with known energy values and 50 entirely new levels belonging to even configurations in
La. In this work a few more electronic levels are presented. Classification of these levels
is still a little doubtful, but they might prove very helpful in solving some problems in
calculation of radial integrals with a semiempirical method.
Procedure of investigation of new levels (described in detail in [1]) begins with measurement
of hyperfine structure of unclassified spectral lines of lanthanum with laser spectroscopy
in a hollow cathode discharge with optogalvanic detection. Afterwards an initial
identification of the lower and the upper levels involved follows. Finally the correctness of
identification is verified by search for fluorescence channels from the lower (known) level.
Acknowledgment
This work was partially supported by Poznań University of Technology under project DS 63-
029/09.
References
[1] B. Furmann, D. Stefanska and J. Dembczynski, Experimental investigations of the
hyperfine structure in neutral La part I (odd configurations levels) submitted to J. Phys.
B: At. Mol. Opt. Phys.
[2] B. Furmann, D. Stefanska and J. Dembczynski, Experimental investigations of the
hyperfine structure in neutral La part II (even configurations levels) submitted to J.
Phys. B: At. Mol. Opt. Phys.
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