Lehmann, C. S.Picon, A.Bostedt, C.Rudenko, ArtemMarinelli, A.Moonshiram, D.Osipov, T.Rolles, DanielBerrah, N.Bomme, C.Bucher, M.Doumy, G.Erk, B.Ferguson, K. R.Gorkhover, T.Ho, P. J.Kanter, E. P.Krassig, B.Krzywinski, J.Lutman, A. A.March, A. M.Ray, D.Young, L.Pratt, S. T.Southworth, S. H.2017-04-102017-04-102016-07-26http://hdl.handle.net/2097/35359Citation: Lehmann, C. S., Picon, A., Bostedt, C., Rudenko, A., Marinelli, A., Moonshiram, D., . . . Southworth, S. H. (2016). Ultrafast x-ray-induced nuclear dynamics in diatomic molecules using femtosecond x-ray-pump-x-ray-probe spectroscopy. Physical Review A, 94(1), 7. doi:10.1103/PhysRevA.94.013426The capability of generating two intense, femtosecond x-ray pulses with a controlled time delay opens the possibility of performing time-resolved experiments for x-ray-induced phenomena. We have applied this capability to study the photoinduced dynamics in diatomic molecules. In molecules composed of low-Z elements, K-shell ionization creates a core-hole state in which the main decay mode is an Auger process involving two electrons in the valence shell. After Auger decay, the nuclear wave packets of the transient two-valence-hole states continue evolving on the femtosecond time scale, leading either to separated atomic ions or long-lived quasibound states. By using an x-ray pump and an x-ray probe pulse tuned above the K-shell ionization threshold of the nitrogen molecule, we are able to observe ion dissociation in progress by measuring the time-dependent kinetic energy releases of different breakup channels. We simulated the measurements on N-2 with a molecular dynamics model that accounts for K-shell ionization, Auger decay, and the time evolution of the nuclear wave packets. In addition to explaining the time-dependent feature in the measured kinetic energy release distributions from the dissociative states, the simulation also reveals the contributions of quasibound states.This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).http://rightsstatements.org/vocab/InC/1.0/Free-Electron LaserK-Shell PhotoabsorptionCharge-TransferCross-SectionsAuger-SpectraPhotoionizationArticle