skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: C 1s Near Edge X-ray Absorption Fine Structure (NEXAFS) of substituted benzoic acids: a theoretical and experimental study

Abstract

Ab initio calculations are performed to explain the discrete transitions in experimental C 1s-NEXAFS (near edge X-ray absorption fine structure) spectra of various benzoic acid derivates. Transition energies and oscillator strengths of the contributing C 1s-{pi}* excitations are computed using the ADC(2) (second-order algebraic-diagrammatic construction) method. This method is demonstrated to be well suited for the finite electronic systems represented by these simple organic acids. There is good agreement between experiment and theory reproducing all the relevant spectral features. Some transitions can only be assigned based on a theoretical foundation. Remaining discrepancies between experimental and computed spectra are discussed.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
BROOKHAVEN NATIONAL LABORATORY (BNL), NATIONAL SYNCHROTRON LIGHT SOURCE (NSLS)
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930284
Report Number(s):
BNL-80988-2008-JA
Journal ID: ISSN 0368-2048; JESRAW; TRN: US200822%%1243
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Electron Spectroscopy and Related Phenomena; Journal Volume: 154
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; X-RAY SPECTROSCOPY; ALKYL BENZENESULFONATES; BENZOIC ACID; OSCILLATOR STRENGTHS; CALCULATION METHODS; ENERGY-LEVEL TRANSITIONS

Citation Formats

Baldea,I., Schimmelpfennig, B., Plaschke, M., Rothe, J., Schirmer, J., Trofimov, A., and Fanghaenel, T. C 1s Near Edge X-ray Absorption Fine Structure (NEXAFS) of substituted benzoic acids: a theoretical and experimental study. United States: N. p., 2007. Web. doi:10.1016/j.elspec.2006.12.024.
Baldea,I., Schimmelpfennig, B., Plaschke, M., Rothe, J., Schirmer, J., Trofimov, A., & Fanghaenel, T. C 1s Near Edge X-ray Absorption Fine Structure (NEXAFS) of substituted benzoic acids: a theoretical and experimental study. United States. doi:10.1016/j.elspec.2006.12.024.
Baldea,I., Schimmelpfennig, B., Plaschke, M., Rothe, J., Schirmer, J., Trofimov, A., and Fanghaenel, T. Mon . "C 1s Near Edge X-ray Absorption Fine Structure (NEXAFS) of substituted benzoic acids: a theoretical and experimental study". United States. doi:10.1016/j.elspec.2006.12.024.
@article{osti_930284,
title = {C 1s Near Edge X-ray Absorption Fine Structure (NEXAFS) of substituted benzoic acids: a theoretical and experimental study},
author = {Baldea,I. and Schimmelpfennig, B. and Plaschke, M. and Rothe, J. and Schirmer, J. and Trofimov, A. and Fanghaenel, T.},
abstractNote = {Ab initio calculations are performed to explain the discrete transitions in experimental C 1s-NEXAFS (near edge X-ray absorption fine structure) spectra of various benzoic acid derivates. Transition energies and oscillator strengths of the contributing C 1s-{pi}* excitations are computed using the ADC(2) (second-order algebraic-diagrammatic construction) method. This method is demonstrated to be well suited for the finite electronic systems represented by these simple organic acids. There is good agreement between experiment and theory reproducing all the relevant spectral features. Some transitions can only be assigned based on a theoretical foundation. Remaining discrepancies between experimental and computed spectra are discussed.},
doi = {10.1016/j.elspec.2006.12.024},
journal = {Journal of Electron Spectroscopy and Related Phenomena},
number = ,
volume = 154,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The speciation and quantification of sulfur species based on sulfur K-edge x-ray absorption spectroscopy is of wide interest, particularly for biological and petroleum science. These tasks require a firm understanding of the sulfur 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of relevant species. To this end, we have examined the gas phase sulfur 1s NEXAFS spectra of a group of simple thiol and thioether compounds. These high-resolution gas phase spectra are free of solid-state broadening, charging, and saturation effects common in the NEXAFS spectra of solids. These experimental data have been further analyzed with the aid of improved virtualmore » orbital Hartree-Fock ab initio calculations. The experimental sulfur 1s NEXAFS spectra show fine features predicted by calculation, and the combination of experiment and calculation has been used to improve assignment of spectroscopic features relevant for the speciation and quantification of the sulfur compounds.« less
  • Curved-wave-multiple-scattering cluster calculations with the FEFF6 code were used to interpret experimental AlK-edge near-edge X-ray absorption fine structure (NEXAFS) spectra of various minerals and Y zeolites for energies {approximately}15 eV above threshold. Octahedral, tetrahedral, and square planar geometries of Al can be easily distinguished from each other utilizing characteristic features in the NEXAFS data. NEXAFS line shapes are used for determining the geometrical conformations of Al atoms in Y zeolites with one or more conformational geometries. In the H-Y zeolite, separate contributions to the NEXAFS from tetrahedrally and octahedrally coordinated Al atoms are identified. The differences in the octahedrally coordinatedmore » Al spectra in the H-Y zeolite compared with spectra for standard octahedrally coordinated Al compounds can be attributed to the presence of very small nonregular clusters of octahedrally coordinated Al dispersed over the zeolite. However, the presence of some pentacoordinated Al cannot be excluded.« less
  • No abstract prepared.
  • Near edge x-ray absorption fine structure spectra have been measured and interpreted by means of density functional theory for five different azabenzenes (pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine) in the gas phase. The experimental and theoretical spectra at the N 1s and C 1s edges show a strong resonance assigned to the transition of the 1s electron in the respective N or C atoms to the lowest unoccupied molecular orbital with {pi}* symmetry. As opposed to the N 1s edge, at the C 1s edge this resonance is split due to the different environments of the core hole atom inmore » the molecule. The shift in atomic core-level energy due to a specific chemical environment is explained with the higher electronegativity of the N atom compared to the C atom. The remaining resonances below the ionization potential (IP) are associated to {sigma} or {pi} orbitals with mixed valence/Rydberg character. Upon N addition, a reduction of intensity is observed in the Rydberg region at both edges as compared to the intensity in the continuum. Above the IP one or more resonances are seen and ascribed here to transitions to {sigma}* orbitals. Calculating the experimental and theoretical {delta}{sub {pi}} term values at both edges, we observe that they are almost the same within {+-}1 eV as expected for isoelectronic bonded pairs. The term values of the {pi}* and {sigma}* resonances are discussed in terms of the total Z number of the atoms participating in the bond.« less
  • No abstract prepared.