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Title: Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy

Abstract

We describe an advanced setup for time-resolved x-ray absorption fine structure (XAFS) Spectroscopy with picosecond temporal resolution. It combines an intense femtosecond laser source synchronized to the x-ray pulses delivered into the microXAS beamline of the Swiss Light Source (SLS). The setup is applied to measure the short-lived high-spin geometric structure of photoexcited aqueous Fe(bpy)3 at room temperature.

Authors:
 [1];  [2]; ; ; ; ; ;  [1]; ; ;  [3];  [4]
  1. Laboratoire de Spectroscopie Ultrarapide (LSU), Ecole Polytechnique Federale de Lausanne (EPFL), BSP, CH-1015 Lausanne (Switzerland)
  2. (Switzerland)
  3. Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland)
  4. Departement de Chimie Physique, Universite de Geneve, CH-1121 Geneva (Switzerland)
Publication Date:
OSTI Identifier:
21054620
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644425; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; FINE STRUCTURE; IRON COMPOUNDS; LIQUIDS; MOLECULAR STRUCTURE; ORGANIC COMPOUNDS; PULSES; SPIN; SWISS LIGHT SOURCE; TIME RESOLUTION; TRANSIENTS; TRANSITION ELEMENTS; X-RAY SPECTRA; X-RAY SPECTROSCOPY

Citation Formats

Gawelda, W., Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI, Pham, V. T., El Nahhas, A., Kaiser, M., Zaushitsyn, Y., Bressler, C., Chergui, M., Johnson, S. L., Grolimund, D., Abela, R., and Hauser, A.. Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy. United States: N. p., 2007. Web. doi:10.1063/1.2644425.
Gawelda, W., Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI, Pham, V. T., El Nahhas, A., Kaiser, M., Zaushitsyn, Y., Bressler, C., Chergui, M., Johnson, S. L., Grolimund, D., Abela, R., & Hauser, A.. Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy. United States. doi:10.1063/1.2644425.
Gawelda, W., Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI, Pham, V. T., El Nahhas, A., Kaiser, M., Zaushitsyn, Y., Bressler, C., Chergui, M., Johnson, S. L., Grolimund, D., Abela, R., and Hauser, A.. Fri . "Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy". United States. doi:10.1063/1.2644425.
@article{osti_21054620,
title = {Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy},
author = {Gawelda, W. and Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI and Pham, V. T. and El Nahhas, A. and Kaiser, M. and Zaushitsyn, Y. and Bressler, C. and Chergui, M. and Johnson, S. L. and Grolimund, D. and Abela, R. and Hauser, A.},
abstractNote = {We describe an advanced setup for time-resolved x-ray absorption fine structure (XAFS) Spectroscopy with picosecond temporal resolution. It combines an intense femtosecond laser source synchronized to the x-ray pulses delivered into the microXAS beamline of the Swiss Light Source (SLS). The setup is applied to measure the short-lived high-spin geometric structure of photoexcited aqueous Fe(bpy)3 at room temperature.},
doi = {10.1063/1.2644425},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • Transient molecular structures along chemical reaction pathways are important for predicting molecular reactivity, understanding reaction mechanisms, as well as controlling reaction pathways. During the past decade, X-ray transient absorption spectroscopy (XTA, or LITR-XAS, laser-initiated X-ray absorption spectroscopy), analogous to the commonly used optical transient absorption spectroscopy, has been developed. XTA uses a laser pulse to trigger a fundamental chemical process, and an X-ray pulse(s) to probe transient structures as a function of the time delay between the pump and probe pulses. Using X-ray pulses with high photon flux from synchrotron sources, transient electronic and molecular structures of metal complexes havemore » been studied in disordered media from homogeneous solutions to heterogeneous solution-solid interfaces. Several examples from the studies at the Advanced Photon Source in Argonne National Laboratory are summarized, including excited-state metalloporphyrins, metal-to-ligand charge transfer (MLCT) states of transition metal complexes, and charge transfer states of metal complexes at the interface with semiconductor nanoparticles. Recent developments of the method are briefly described followed by a future prospective of XTA. It is envisioned that concurrent developments in X-ray free-electron lasers and synchrotron X-ray facilities as well as other table-top laser-driven femtosecond X-ray sources will make many breakthroughs and realise dreams of visualizing molecular movies and snapshots, which ultimately enable chemical reaction pathways to be controlled.« less
  • No abstract prepared.
  • No abstract prepared.
  • This study uses transient X-ray absorption (XA) spectroscopy and timedependent density functional theory (TD-DFT) to directly visualize the charge density around the metal atom and the surrounding ligands following an ultrafast metal-to-ligand charge-transfer (MLCT) process in the widely used RuII solar cell dye, Ru(dcbpy)2(NCS)2 (termed N3). We measure the Ru L-edge XA spectra of the singlet ground (1A1) and the transient triplet (3MLCT) excited state of N34 and perform TD-DFT calculations of 2p core-level excitations, which identify a unique spectral signature of the electron density on the NCS ligands. We find that the Ru 2p, Ru eg, and NCS orbitalsmore » are stabilized by 2.0, 1.0, and 0.6 eV, respectively, in the transient 3MLCT state of the dye. These results highlight the role of the NCS ligands in governing the oxidation state of the Ru center.« less