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J Phys Chem A. 2011 Jun 16;115(23):6239-49. doi: 10.1021/jp111674s. Epub 2011 Feb 21.

Flexible H2O2 in water: electronic structure from photoelectron spectroscopy and ab initio calculations.

Author information

1
Helmholtz-Zentrum Berlin für Materialien und Energie, and BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.

Abstract

The effect of hydration on the electronic structure of H(2)O(2) is investigated by liquid-jet photoelectron spectroscopy measurements and ab initio calculations. Experimental valence electron binding energies of the H(2)O(2) orbitals in water are, on average, 1.9 eV red-shifted with respect to the gas-phase molecule. A smaller width of the first peak was observed in the photoelectron spectrum from the solution. Our experiment is complemented by simulated photoelectron spectra, calculated at the ab initio level of theory (with EOM-IP-CCSD and DFT methods), and using path-integral sampling of the ground-state density. The observed shift in ionization energy upon solvation is attributed to a combination of nonspecific electrostatic effects (long-range polarization) and of the specific interactions between H(2)O(2) and H(2)O molecules in the first solvation shell. Changes in peak widths are found to result from merging of the two lowest ionized states of H(2)O(2) in water due to conformational changes upon solvation. Hydration effects on H(2)O(2) are stronger than on the H(2)O molecule. In addition to valence spectra, we report oxygen 1s core-level photoelectron spectra from H(2)O(2)(aq), and observed energies and spectral intensities are discussed qualitatively.

PMID:
21332235
DOI:
10.1021/jp111674s
[Indexed for MEDLINE]

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