Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 186 Double Excitations in Helium Atoms and Lithium Compounds MARCUS AGÅKER ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 UPPSALA ISBN 91-554-6572-2 2006 urn:nbn:se:uu:diva-6889 ! ""! #"$#% & & & ' ( ) * ' +,- ' ""!' * . + / 0 ' + ' #1!' ##2 ' ' 3456 7#8%%28!%9 8 ' ( & ' & & & & & ' 0 & & & ' : 8 && ; & ) < & ) ! ' + & & & ) - &' ( ) & & ) & & ' 8 =:3>4?' ( "# " # "$ "% ) "&# " &' "$(' 4 ) ) & < & & ) ' + & & & & & ' )* + 4 & >8 >8 , -./# 0# - # $ 1 2'3# # 456277 # * @ +,- ""! 3446 #!%#8! #2 3456 7#8%%28!%9 8 $ $$$ 8!117 = $AA '-'A B C $ $$$ 8!117? “… after 5 years of studies, taking 40p of courses, supervising 16 classes of 428 students in the course lab, 94 days as beamline manager at MAX-lab, 271 days of traveling, of which 250 days at synchrotrons divided on 30 oc- casions, with 3768 hours of beamtime, producing 2695 X-ray absorption spectra and 1311 soft X-ray emission spectra, I am finally done.” List of papers This thesis is based on a collection of articles listed below. Each paper will be referred to in the text by its Roman numeral. I. Resonant Inelastic Photon Scattering in Helium, J. Söderström, M. Agåker, A. Zimina, R. Feifel, S. Eisebitt, R. Follath, G. Reichardt, O. Schwarzkopf, W. Eberhardt, and J.-E. Rubensson, in manuscript. II. Radiative and Relativistic Effects in the Decay of Highly Excited States in Helium, T. W. Gorczyca, J.-E. Rubensson, C. Såthe, M. Ström, M. Agåker, D. Ding, S. Stranges, R. Richter, and M. Alagia, Phys. Rev. Lett. 85, 1202 (2000) III. Double Excitations of Helium in Weak Static Electric Fields, C. Såthe, M. Ström, M. Agåker, J. Söderström, J.-E. Rubensson, R. Richter, M. Alagia, S. Stranges, T. W. Gorczyca, and F. Robicheaux, Phys. Rev. Lett. 96, 043002 (2006) IV. Magnetic-Field Induced Enhancement in the Fluorescence Yield Spectrum of Doubly Excited States in Helium, M.Ström, C. Såthe, M. Agåker, J. Söderström, J.-E. Rubensson S. Stranges, R. Richter, M. Alagia, T. W. Gorczyca, and F. Robicheaux, in manuscript. V. Resonant Inelastic Soft X-ray Scattering at Hollow Lithium States in Solid LiCl, M. Agåker, J. Söderström, T. Käämbre, C. Glover, L. Gridneva, T. Schmitt, A. Augustsson, M. Mattesini, R. Ahuja, J.- E. Rubensson, Phys. Rev. Lett. 93, 016404 (2004) VI. Resonant Inelastic Soft X-ray Scattering at Double Core Excita- tions in Solid LiCl, M. Agåker, T. Käämbre, C. Glover, T. Schmitt, M. Mattesini, R. Ahuja, J. Söderström, and J.-E Rubensson, submitted Phys. Rev. B VII. Double Core Excitations in Lithium Halides, M. Agåker and J.-E. Rubensson, in manuscript VIII. Double Excitations at the Lithium Site in Solid Li Compounds, M. Agåker and J.-E. Rubensson, in manuscript IX. Multi-Center Resonant Inelastic Soft X-ray Scattering in LiI?, M. Agåker and J.-E. Rubensson, in manuscript Reprints were made with permission of the publisher. The following articles have been omitted from the thesis. They were omitted either due to the character of the material, or due to the limited extent of my contribution. x X-ray-emission-threshold-electron coincidence spectroscopy, J. Söderström, M. Alagia, R. Richter, S. Stranges, M. Agåker, M. Ström, S. Sorensen, and J.- E. Rubensson, Journal of Electron Spectroscopy and Related Phenomena, 141, 161 (2004) x X-ray yield and selectively excited X-ray emission spectra of atenolol and nadolol, J. Söderström, J. Gråsjö, S. Kashtanov, C. Bergström, M. Agåker, T. Schmitt, A. Augustsson, L. Duda, G. Jinghua, J. Nordgren, Y. Luo, P. Artursson, and J.-E. Rubensson, Journal of Electron Spectroscopy and Related Phenomena, 144, 283 (2005) x Core level ionization dynamics in small molecules studied by X-ray-emission threshold-electron coincidence spectroscopy, M. Alagia, R. Richter, S. Stranges, M. Agåker, M. Ström, J. Söderström, C. Såthe, R. Feifel, S. Sorensen, A. De Fanis, K. Ueda, R. Fink, and J.-E. Rubensson, Phys. Rev. A 71, 012506 (2005) Comments on my participation Experimental studies performed at synchrotron facilities are always an effort of many people, which is often reflected by the lengthy author lists. My con- tribution to the papers has been on the experimental side for all papers and the analysis and writing for some. Paper I is based upon results from ex- periments performed at BESSY-II in Berlin, Germany. Here I was only pre- sent during one of the two beamtimes. I took part in the onsite preparations of the experiment and for the actual recording of data, but I was not involved in the writing. Papers II-IV contain results from measurements performed at the synchrotron facility ELETTRA in Trieste, Italy. For these measurements I was responsible for designing two of the three experimental set-ups used, as well as partaking in the general preparations. I also participated in the measurements at the synchrotron for all three papers and was partially in- volved in the analysis and discussion of the data, others made the final analysis and the writing up of the papers. Papers V to IX contain experi- ments conducted at MAX-Lab in Lund, Sweden. These experiments are the ones in which I have been most active. I designed the experimental set-up, made the preparations for the measurements and carried out the experiment. I also developed the experimental methods needed to avoid problems associ- ated with measurements on sensitive samples and on states with a low yield. This later part of the work included the developments of sample preparation procedures, calibrating and optimizing refocusing optics, development of “slitless” measuring methods as well as the writing of a computer program for measuring that can handle the control of undulator, monchromator and manipulator simultaneously or independently as well as data collection. I have also done the analysis of the experimental data, identified many states not known earlier and demonstrated their participation in various physical processes. The writing of the papers has been done in close collaboration with Professor J.-E. Rubensson. Contents Introduction...................................................................................................13 Background...................................................................................................14 Short history .............................................................................................14 Quantum mechanics .................................................................................16 Electronic states...................................................................................16 Independent particle model.............................................................18 Configuration interaction ................................................................22 DESB ..............................................................................................23 Hyperspherical base functions ........................................................24 Molecular orbitals ...........................................................................25 Solid state bands..............................................................................28 Interaction of radiation with matter .....................................................36 Dipole approximation .....................................................................37 Quantized fields ..............................................................................39 Transitions and CI...........................................................................43 Synchrotron radiation...............................................................................44 Bending magnets .................................................................................48 Insertion devices ..................................................................................50 Undulator ........................................................................................53 Wiggler ...........................................................................................54 Concepts of Soft X-ray spectroscopy.......................................................56 X-ray absorption ..................................................................................58 X-ray emission.....................................................................................59 Resonant Inelastic X-ray Scattering ....................................................60 Angular dependence ............................................................................61 Experimental.................................................................................................63 Beam lines................................................................................................63 Optics...................................................................................................64 Endstation ............................................................................................65 Control.................................................................................................65 Absorption measurements ........................................................................65