Flexible H2O2 in Water: Electronic Structure from Photoelectron Spectroscopy and Ab Initio Calculations

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• 作者：Stephan Th眉rmer ; Robert Seidel ; Bernd Winter ; Milan On膷谩k ; Petr Slav铆膷ek
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：June 16, 2011
• 年：2011
• 卷：115
• 期：23
• 页码：6239-6249
• 全文大小：1175K
• 年卷期：v.115,no.23(June 16, 2011)
• ISSN：1520-5215

文摘

The effect of hydration on the electronic structure of H₂O₂ is investigated by liquid-jet photoelectron spectroscopy measurements and ab initio calculations. Experimental valence electron binding energies of the H₂O₂ 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 H₂O₂ and H₂O molecules in the first solvation shell. Changes in peak widths are found to result from merging of the two lowest ionized states of H₂O₂ in water due to conformational changes upon solvation. Hydration effects on H₂O₂ are stronger than on the H₂O molecule. In addition to valence spectra, we report oxygen 1s core-level photoelectron spectra from H₂O₂(aq), and observed energies and spectral intensities are discussed qualitatively.