Abstract

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Orbital-specific mapping of chemical dynamics with ultrafast x-rays

I-20

Orbital-specific mapping of chemical dynamics with ultrafast x-rays


Ph. Wernet1*

1Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany

Charge and spin density changes at the metal sites of transition-metal complexes and in metalloproteins determine reactivity and selectivity. To understand their function and to optimize complexes for photocatalytic applications the changes of charge and spin densities need to be mapped and ultimately controlled. I will present our approach of using atom- and orbital-specific x-ray free-electron laser spectroscopy [1] and quantum chemical theory [2] to map the frontier-orbital interactions of a transition-metal complex in solution on the femtosecond time scale [3]. Spin crossover and ligation are found to define the excited-state dynamics. The solution pathways will be contrasted to the gas-phase dynamics of the same molecule measured with photoelectron spectroscopy at the x-ray free-electron laser FLASH and with a lab-based source of femtosecond VUV pulses based on high-order harmonic generation. It is demonstrated how correlating orbital symmetry and orbital interactions with spin multiplicity allows for determining the reactivity of short-lived reaction intermediates. I will discuss how this complements approaches that probe structural dynamics and how it can be extended [4] to map the local chemical interactions and their dynamical evolution in metalloproteins.

References:

[1] Ph. Wernet. Phys. Chem. Chem. Phys. 13, 16941 (2011).

[2] I. Josefsson, K. Kunnus, S. Schreck, A. Föhlisch, F.M.F. de Groot, Ph. Wernet, and M. Odelius. J. Phys. Chem. Lett. 3, 3565 (2012).

[3] Ph. Wernet, K. Kunnus, I. Josefsson, I. Rajkovic, W. Quevedo, M. Beye, S. Schreck, S. Grübel, M. Scholz, D. Nordlund, W. Zhang, R. W. Hartsock, W. F. Schlotter, J. J. Turner, B. Kennedy, F. Hennies, F. M. F. de Groot, K. J. Gaffney, S. Techert, M. Odelius, and A. Föhlisch. Nature 520, 78 (2015).

[4] R. Mitzner, J. Rehanek, J. Kern, S. Gul, J. Hattne, T. Taguchi, R. Alonso-Mori, R. Tran, C. Weniger, H. Schröder, W. Quevedo, H. Laksmono, R. G. Sierra, G. Han, B. Lassalle-Kaiser, S. Koroidov, K. Kubicek, S. Schreck, K. Kunnus, M. Brzhezinskaya, A. Firsov, M. P. Minitti, J. J. Turner, S. Moeller, N. K. Sauter, M. J. Bogan, D. Nordlund, W. F. Schlotter, J. Messinger, A. Borovik, S. Techert, F. M. F. de Groot, A. Föhlisch, A. Erko, U. Bergmann, V. K. Yachandra, Ph. Wernet, and J. Yano. J. Phys. Chem. Lett. 4, 3641 (2013).