Abstract:

We have been stimulating a revival of scientific interest in processes following absorption of a tender x-ray photon by an isolated atom or molecule.  This is enabled by recent instrumentation developments which allow one to follow ultrafast processes on the subfemtosecond time scale. We have developed a Hard X-ray Photoelectron Spectrometer [1], a Reaction Microscope [2] and a X-ray spectrometer [3] dedicated to this purpose. I will concentrate my talk on recoil effects [4] occuring after the ejection of a fast photoelectron, on localization/delocalization of a deep core hole [5], on double core hole spectroscopy [6, 7] as well as on ultrafast fragmentation occuring after deep inner shell excitation [8, 9].

[1] D. Céolin et al., Journal of Electron Spectroscopy and Related Phenomena 190 188 (2013) [2] C. Bomme et al., Rev. Sci. Instrum. 84, 103104 (2013)
[3] L. Journel et al., Rev. Sci. Instrum. 80, 093105 (2009)
[4] M. Simon et al., Nature Communications 5 4069 (2014)
[5] R. Guillemin et al., Nature Communications 6 6166 (2015)
[6] R. Püttner et al., Phys. Rev. Lett. 114, 093001 (2015)
[7] G. Goldsztejn et al., Phys. Rev. Lett. 117 133001 (2016)
[8] O. Travnikova et al., Phys. Rev. Lett. 116 213001 (2016)
[9] O. Travnikova et al., Phys. Rev. Lett. 118, 213001 (2017)