Observing Solvation Dynamics with Simultaneous Femtosecond X-ray Emission Spectroscopy and X-ray Scattering.

Haldrup K; Gawelda W; Abela R; Alonso-Mori R; Bergmann U; Bordage A; Cammarata M; Canton SE; Dohn AO; van Driel TB; Fritz DM; Galler A; Glatzel P; Harlang T; Kjær KS; Lemke HT; Møller KB; Németh Z; Pápai M; Sas N; Uhlig J; Zhu D; Vankó G; Sundström V; Nielsen MM; Bressler C

doi:10.1021/acs.jpcb.5b12471

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Journal article

Observing Solvation Dynamics with Simultaneous Femtosecond X-ray Emission Spectroscopy and X-ray Scattering.

Haldrup K Department of Physics, Technical University of Denmark , Fysikvej 307, DK-2800 Kongens Lyngby, Denmark.
Gawelda W European XFEL GmbH , Albert-Einstein-Ring 19, D-22761 Hamburg, Germany.
Abela R Paul Scherrer Institut, SwissFEL, CH-5232 Villigen PSI, Switzerland.
Alonso-Mori R LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Bergmann U LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Bordage A Wigner Research Centre for Physics, Hungarian Academy Sciences, H-1525 Budapest, Hungary.
Cammarata M LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Canton SE Department of Chemical Physics, Lund University , Box 118, S-22100 Lund, Sweden.
Dohn AO Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark.
van Driel TB Department of Physics, Technical University of Denmark , Fysikvej 307, DK-2800 Kongens Lyngby, Denmark.
Fritz DM LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Galler A European XFEL GmbH , Albert-Einstein-Ring 19, D-22761 Hamburg, Germany.
Glatzel P European Synchrotron Radiation Facility , F-38043 Grenoble Cedex 9, France.
Harlang T Department of Chemical Physics, Lund University , Box 118, S-22100 Lund, Sweden.
Kjær KS Department of Physics, Technical University of Denmark , Fysikvej 307, DK-2800 Kongens Lyngby, Denmark.
Lemke HT LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Møller KB Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark.
Németh Z Wigner Research Centre for Physics, Hungarian Academy Sciences, H-1525 Budapest, Hungary.
Pápai M Department of Chemistry, Technical University of Denmark , Kemitorvet 207, DK-2800 Kongens Lyngby, Denmark.
Sas N Wigner Research Centre for Physics, Hungarian Academy Sciences, H-1525 Budapest, Hungary.
Uhlig J Department of Chemical Physics, Lund University , Box 118, S-22100 Lund, Sweden.
Zhu D LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
Vankó G Wigner Research Centre for Physics, Hungarian Academy Sciences, H-1525 Budapest, Hungary.
Sundström V Department of Chemical Physics, Lund University , Box 118, S-22100 Lund, Sweden.
Nielsen MM Department of Physics, Technical University of Denmark , Fysikvej 307, DK-2800 Kongens Lyngby, Denmark.
Bressler C European XFEL GmbH , Albert-Einstein-Ring 19, D-22761 Hamburg, Germany.

2016-01-20

Published in:

The journal of physical chemistry. B. - 2016

Physical and Theoretical Chemistry

English In liquid phase chemistry dynamic solute-solvent interactions often govern the path, ultimate outcome, and efficiency of chemical reactions. These steps involve many-body movements on subpicosecond time scales and thus ultrafast structural tools capable of capturing both intramolecular electronic and structural changes, and local solvent structural changes are desired. We have studied the intra- and intermolecular dynamics of a model chromophore, aqueous [Fe(bpy)3](2+), with complementary X-ray tools in a single experiment exploiting intense XFEL radiation as a probe. We monitored the ultrafast structural rearrangement of the solute with X-ray emission spectroscopy, thus establishing time zero for the ensuing X-ray diffuse scattering analysis. The simultaneously recorded X-ray diffuse scattering patterns reveal slower subpicosecond dynamics triggered by the intramolecular structural dynamics of the photoexcited solute. By simultaneous combination of both methods only, we can extract new information about the solvation dynamic processes unfolding during the first picosecond (ps). The measured bulk solvent density increase of 0.2% indicates a dramatic change of the solvation shell around each photoexcited solute, confirming previous ab initio molecular dynamics simulations. Structural changes in the aqueous solvent associated with density and temperature changes occur with ∼1 ps time constants, characteristic for structural dynamics in water. This slower time scale of the solvent response allows us to directly observe the structure of the excited solute molecules well before the solvent contributions become dominant.

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