The strong La line 6520.644 ? is present in a Fourier Transform Spectrum (signal to noise ratio of 240), but its wavelength in commonly used tables (e.g. [1]) is given as 6520.770 ?, while in [2] the wavelength is given as 6520.74 ?, unclassified, with the remark “h” (hazy). The line could not be classified using known energy levels of the La atom (La I) and its first ion (La II). It appears as a single broadened peak. By a combination of laser optogalvanic spectroscopy, laser-induced fluorescence and Doppler-reduced saturation spectroscopy we could introduce a new even parity La I energy level, 35449.041 cm -1, J = 13/2, with hyperfine (hf) constants A = ?8.0(5) MHz, B = 10(10) MHz. For a second, up to now unknown neighbouring La I line (wavelength 6519.869 ?) we introduced another even parity energy level involved in the formation of the line, 41207.994 cm -1, J = 13/2, A = 91.6(5) MHz, B = 170(50) MHz. We tried also to explain why in old tables the wavelength given was so different.
References
[1]
Harrison, G.R. (1969) Wavelength Tables. Massachusetts Institute of Technology, The M.I.T. Press, Cambridge, Massachusetts, and London, England
[2]
Meggers, W.F., Corliss, C.H., and Scribner, B.F. (1961) National Bureau of Standards Monograph 32. Part I, U.S. Government Printing Office, Washington D.C.
[3]
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http://dx.doi.org/10.1016/0092-640X(89)90008-9
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[8]
Siddiqui, I., Shamim, K., Gamper, B., Dembczyński, J. and Windholz, L. (2013) Optogalvanic Spectroscopy of the Hyperfine Structure of Weak La I Lines: Discovery of New Even Parity Fine Structure Levels. Journal of Physics B: Atomic, Molecular and Optical Physics, 46, 065002. http://dx.doi.org/10.1088/0953-4075/46/6/065002
[9]
Gamper, B., G?owacki, P., Siddiqui, I., Dembczyński, J. and Windholz, L. (2014) New Even Parity Fine Structure Levels of the Lanthanum Atom Discovered by Means of Optogalvanic Spectroscopy. Journal of Physics B, in Press.
[10]
Childs, W.J. and Goodman, L.S. (1971) Hyperfine and Zeeman Studies of Low-Lying Atomic Levels of La139 and the Nuclear Electric-Quadrupole Moment. Physical Review A, 3, 25.
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Furmann, B., Stefańska, D. and Dembczyński, J. (2007) Hyperfine Structure Analysis Odd Configurations Levels in neutral Lanthanum: I. Experimental. Physica Scripta, 76, 264
http://dx.doi.org/10.1088/0031-8949/76/3/010
[12]
Ba?ar, Gü., Ba?ar, G?. and Kr?ger, S. (2009) High Resolution Measurements of the Hyperfine Structure of Atomic Lanthanum for Energetically Low Lying Levels of Odd Parity. Optics Communications, 282, 562-567.
http://dx.doi.org/10.1016/j.optcom.2008.10.048
