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Title: Ca K-Edge XAS as a Probe of Calcium Centers in Complex Systems

Calcium K-edge pre-edges coupled with TD-DFT theoretical calculation of spectra provide a powerful approach for the characterization of complex calcium centers in inorganic and bioinorganic chemistry. Herein, Ca K-edge X-ray absorption spectroscopy (XAS) is developed as a means to characterize the local environment of calcium centers. The spectra for six, seven, and eight coordinate inorganic and molecular calcium complexes were analyzed and determined to be primarily influenced by the coordination environment and site symmetry at the calcium center. The experimental results are closely correlated to time-dependent density functional theory (TD-DFT) calculations of the XAS spectra. The applicability of this methodology to complex systems was investigated using structural mimics of the oxygen-evolving complex (OEC) of PSII. It was found that Ca K-edge XAS is a sensitive probe for structural changes occurring in the cubane heterometallic cluster due to Mn oxidation. Future applications to the OEC are discussed.
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [4] ;  [5] ;  [6] ;  [1] ;  [2] ;  [2] ;  [4] ;  [3] ;  [2] ;  [1]
  1. Max Planck Inst. for Chemical Energy Conversion (Germany)
  2. Univ. Grenobles Alpes (France)
  3. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. Laboratoire de Reconnaissance Ionique et Chimie de Coordination (LCIB, SCIB, INAC, CEA Grenoble) (France)
  6. Max Planck Inst. for Chemical Energy Conversion (Germany)Max Planck Inst. for Chemical Energy Conversion (Germany)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC02-05CH11231; R01 GM102687A; CM1202; ANR-13-BS07-0015-01; AC02-76SF00515
Published Article
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 54; Journal Issue: 4; Journal ID: ISSN 0020-1669
American Chemical Society (ACS)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States