Strong Laser Fields
Department of Molecular and Optical Physics - University of Freiburg, Germany.
Experimental studies of partial photodetachment cross sections in K- below the K(7 2 P) threshold
A.O. Lindahl 1, J. Rohlén 1, H. Hultgren 1,2, I.Yu. Kiyan 2, D.J. Pegg 3, C.W. Walter 4, and D. Hanstorp 1
1 Department of Physics, University of Gothenburg, SE-412 96 Gothenburg, Sweden
2 Department of Molecular and Optical Physics, University of Freiburg, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany
3 Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
4 Department of Physics and Astronomy, Denison University, Granville, Ohio 43023, USA
Phys. Rev. A 85, 033415 (2012) [7 pages]
A collinear beams apparatus has been used to determine photodetachment cross sections for K- in the photon energy range 4.250–4.360 eV. State-selective detection, utilizing a resonance ionization scheme, was applied to measure partial cross sections for those channels which leave the residual K atoms in the excited 7 2 S, 5 2 F, and 5 2G states. The energy region studied encompassed the openings of the aforementioned channels, as well as the channel that leaves the K atom in the 7 2 P state. Two previously unobserved resonances were seen in all three partial cross sections between the K(5 2G) and K(7 2P) thresholds. It is shown that a more reliable determination of resonance parameters can be made if the same resonances are observed in several channels. In the region below the K(5 2 F) threshold, three previously observed resonances were investigated [Kiyan et al. Phys. Rev. Lett. 84 5979 (2000)]. A greatly increased modulation of the signal was obtained by detecting in the K(7 2 S) channel instead of the K(5 2 S) channel used in the previous study. Furthermore, the shapes of the cross sections in the threshold regions are discussed. A detailed description of the apparatus and the experimental procedure employed is presented in the paper.
©2012 American Physical Society
PACS: 32.80.Gc, 32.80.Zb, 32.80.Rm