PHYSICS

X-ray fel-induced double core-hole formation in polyatomic molecules

M. Larsson^a, P. Salén^a, P. van der Meulen^a, R. D. Thomas^a, H. T. Schmidt^a, R. Feifel^b, M. N. Piancastelli^b, L. Fang^c, T. Osipov^c, B. Murphy^c, P. Juranic^c, N. Berrah^c, E. Kukk^d, K. Ueda^e, R. Richter^f, K. C. Prince^f, J. D. Bozek^g, С. Bostedt^g, S. Wada^g, M. Tashiro^e, M. Ehara^e, F. Tarantelli<sup>h

a</sup> Stockholm University, Physics Department, 106 91 Stockholm, Sweden
^b Uppsala University, Department of Physics and Astronomy, 751 20 Uppsala, Sweden
^c Western Michigan University, Physics Department, Kalamazoo, MI 49008, USA
^d University of Turku, Department of Physics and Astronomy, 20014 Turku, Finland
^e IMRAM, Tohoku University, Sendai 980-8577, Japan
^f Sincrotrone Trieste, 34149 Basovizza, Trieste, Italy
^g SLAC, LCLS, Menlo Park, CA 94025, USA
^h Chemistry Department, University of Perugia and ISTM-CNR, 06123 Perugia, Italy

Abstract: We use extremely intense, ultrashort soft X-Ray pulses generated by the LCLS X-Ray Free Electron Laser to investigate the production of molecular double core-hole states by sequential two-photon X-Ray absorption. The effect of critical LCLS parameters such as the number of photons per pulse, the pulse duration, and the focal spot size on the photoelectron and Auger spectra is modeled in detail and the results of these simulations are used as an aid in the interpretation of the experimental spectra obtained. We review here the results from the two-photon experiments at LCLS.

Keywords: free electron laser, X-ray laser, polyatomic molecule, double core-hole state.

UDC: 539

Received: 14.11.2011

Language: English