Structural analysis of ultrafast extended x-ray absorption fine structure with subpicometer spatial resolution: Application to spin crossover complexes

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Abstract

We present a novel analysis of time-resolved extended x-ray absorption fine structure (EXAFS) spectra based on the fitting of the experimental transients obtained from optical pump/x-ray probe experiments. We apply it to the analysis of picosecond EXAFS data on aqueous [FeII (bpy)3] 2+, which undergoes a light induced conversion from its low-spin (LS) ground state to the short-lived (τ≈650 ps) excited high-spin (HS) state. A series of EXAFS spectra were simulated for a collection of possible HS structures from which the ground state fit spectrum was subtracted to generate transient difference absorption (TA) spectra. These are then compared with the experimental TA spectrum using a least-squares statistical analysis to derive the structural change. This approach reduces the number of required parameters by cancellation in the differences. It also delivers a unique solution for both the fractional population and the extracted excited state structure. We thus obtain a value of the Fe-N bond elongation in the HS state with subpicometer precision (0.203±0.008 Å).

Detaljer

Författare
  • W. Gawelda
  • R. M. Van Der Veen
  • D. Grolimund
  • R. Abela
  • M. Chergui
  • C. Bressler
  • Van-Thai Pham
Externa organisationer
  • Swiss Federal Institute of Technology
  • Paul Scherrer Institute
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Atom- och molekylfysik och optik
Originalspråkengelska
Artikelnummer124520
TidskriftJournal of Chemical Physics
Volym130
Utgivningsnummer12
StatusPublished - 2009 apr 8
PublikationskategoriForskning
Peer review utfördJa
Externt publiceradJa