Picón, A.Lehmann, C. S.Bostedt, C.Rudenko, A.Marinelli, A.Osipov, T.Rolles, D.Berrah, N.Bomme, C.Bucher, M.Doumy, G.Erk, B.Ferguson, K. R.Gorkhover, T.Ho, P. J.Kanter, E. P.Krässig, B.Krzywinski, J.Lutman, A. A.March, A. M.Moonshiram, D.Ray, D.Young, L.Pratt, S. T.Southworth, S. H.2023-12-072023-12-072016-05-23https://hdl.handle.net/2097/43980New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site.Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International Licensehttps://creativecommons.org/licenses/by-nc-nd/4.0/Text