Dresden 2011 – wissenschaftliches Programm
A 26.57: Poster
Donnerstag, 17. März 2011, 16:00–18:30, P2
Hyperfine structure measurements and discovery of new energy levels in neutral Praseodymium — •Siddiqui Imran, Shamim Khan, Tanweer Iqbal Syed, Bettina Gamper, and Laurentius Windholz — Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz
We present here 14 even and 17 odd parity new energy levels of the neutral praseodymium atom. Free praseodymium atoms in ground and excited states are produced in a hollow cathode discharge lamp by cathode sputtering. The hyperfine structure (hfs) of the spectral lines is investigated by the method of laser induced fluorescence (LIF) spectroscopy. As an example of the method used we discuss briefly the finding of the new level at 27304.431 cm−1, even parity, J = 9/2 and A = 690(1) MHz. Laser excitation of the line at 6004.23 Å is performed and a LIF signal is detected at fluorescence lines 5246.709, 5412.95, 5925.10, 6107.88, 6287.02, 6419.16, and 6620.63 Å. The hfs is then recorded digitally and fitted to find reliable values of angular momentum J, magnetic and electric quadrupole hyperfine constants A and B for the combining fine structure levels. Assuming an unknown upper level, a lower level is searched in the data base of known levels, having the J and A values determined from the fit procedure. A level with 10654.11 cm−1, odd parity, J = 7/2 and A = 169(2) MHz is found. The energy of the upper level is calculated by adding the center of gravity wave number of the excited line to the energy of the lower level. The existence of the new level is checked by at least one additional laser excitation from another known lower level.