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Multi-ionization of atoms and molecules exposed to X-FEL radiation
  Molecular Physics seminar

Monday 31 March 2014
from 10:00 to 11:00
at FA 31
Speaker : Magdalena Kaminska (Atomic Physics Department)
Abstract : An innovative approach to electron spectroscopy has very recently become possible with the advent of X–ray free electron lasers (X-FELs) due to their unique properties of unprecedentedly high peak intensity and ultra-short pulse duration in this spectral region. Utilizing such experimental conditions in combination with a versatile time-of-flight magnetic bottle electron spectrometer of high collection-detection efficiency and the correlation analysis method of covariance mapping [1] allows identification and in-depth examination of complex multi-photon ionization processes in atoms and molecules. In particular, double core hole (DCH) states, where the two vacancies can be created efficiently at X-FELs upon sequential two-photon absorption either on the same atomic site (single-site DCH) or on two different atomic sites of the molecular species (two-site DCH) before the competing Auger decay occurs, are subject of great interest, since the two-site DCH states are expected to show a higher chemical sensitivity compared to single core hole states [2]. Using the Linac Coherent Laser Source (LCLS) X-FEL at Stanford, USA we investigated the formation of DCH states in neon atoms [3] and 4-aminophenol in relation to other competing multi-ionization processes. [1] L.J. Frasinski et al. 1989 Science 246 1029 [2] L.S. Cederbaum et al. 1986 J. Chem. Phys. 85 6513 [3] V. Zhaunerchyk et al. 2013 J. Phys. B: At. Mol. Opt. Phys. 46 164034

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