Structure of the Mn complex in photosystem II: Insights from x-ray spectroscopy
- LBNL Library
We have used Mn K-edge absorption and Kb emission spectroscopies to determine the oxidation states of the Mn complex in the various S-states. We have started exploring the new technique of resonant inelastic X-ray scattering spectroscopy (RIXS); this technique can be characterized as a Raman process that uses K-edge energies (1s to 4p, {approx}6550 eV) to obtain L-edge-like spectra (2p to 3d, {approx}650 eV). The relevance of these data to the oxidation states and structure of the Mn complex is presented. We have obtained EXAFS data from the S0 and S3 states and observed heterogeneity in the Mn-Mn distances, leading us to conclude that there may be three rather than two di-(mu)-oxo bridged units present per tetranuclear Mn cluster. In addition, we have obtained data using Ca/Sr X-ray spectroscopy that provide evidence for a heteronuclear Mn/Ca cluster. The possibility of three di-(mu)-oxo-bridged Mn Mn moieties and the proximity of Ca is incorporated into developing structural models for the Mn cluster. The involvement of bridging and terminal O ligands of Mn in the mechanism of oxygen evolution is discussed in the context of our X-ray spectroscopy results.
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE Director, Office of Science. Office of Basic Energy Sciences. Chemical Sciences, Geosciences, and Biosciences Division; National Institutes of Health (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 823265
- Report Number(s):
- LBNL--50212
- Journal Information:
- Philosophical Transactions of the Royal Society London B, Journal Name: Philosophical Transactions of the Royal Society London B Journal Issue: 1426 Vol. 357
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electronic Structure and Oxidation State Changes in the Mn4Ca Cluster of Photosystem II
Energetics of proton-coupled electron transfer in high-valent Mn{sup 2} ({mu}-O){sup 2} systems: Models for water oxidation by the oxygen-evolving complex of photosystem II