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Electronic Structures of Formic Acid (HCOOH) and Formate (HCOO(-)) in Aqueous Solutions.
Journal article

Electronic Structures of Formic Acid (HCOOH) and Formate (HCOO(-)) in Aqueous Solutions.

  • Brown MA †Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland.
  • Vila F ‡Department of Physics, University of Washington, Seattle, Washington, 98195, United States.
  • Sterrer M §Department of Chemical Physics, Fritz-Haber-Institute der Max-Planck-Gesellschaft, D-14195 Berlin, Germany.
  • Thürmer S ∥Helmholtz-Zentrum Berlin für Materialien und Energie and BESSY, D-12489 Berlin, Germany.
  • Winter B ∥Helmholtz-Zentrum Berlin für Materialien und Energie and BESSY, D-12489 Berlin, Germany.
  • Ammann M ⊥Laboratory for Radiochemistry and Environmental Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
  • Rehr JJ ‡Department of Physics, University of Washington, Seattle, Washington, 98195, United States.
  • van Bokhoven JA †Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich, Switzerland.
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  • 2015-08-21
Published in:
  • The journal of physical chemistry letters. - 2012
DFT
PEY XAS
XAS
XPS
carboxylic acid
complementary experimental probes
in situ
liquid−vapor interface
solute
English The electronic structures of formic acid (HCOOH) and formate (HCOO(-)) have been determined in aqueous solutions over a pH range of 1.88-8.87 using a combination of X-ray photoelectron spectroscopy (XPS), partial electron-yield X-ray absorption spectroscopy (PEY XAS), and density functional theory (DFT). The carbon 1s XPS measurements reveal a binding energy shift of -1.3 eV for deprotonated HCOO(-) compared with neutral HCOOH. Such distinction between neutral HCOOH and deprotonated HCOO(-) cannot be made based solely on the respective carbon K-edge PEY XA spectra. Independent of pH, the C1s → π* state excitations occur at 288.0 eV and may lead to the incorrect conclusion that the energy levels of the π* state are the same for both species. The DFT calculations are consistent with the experimental observations and show a shift to higher energy for both the occupied C1s (lower binding energy) and unoccupied π* orbitals of deprotonated HCOO(-) compared to neutral HCOOH in aqueous solutions.
Language
  • English
Open access status
closed
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Persistent URL
https://folia.unifr.ch/global/documents/108078
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