Electronic Structures of Formic Acid (HCOOH) and Formate (HCOO鈥?/sup>) in Aqueous Solutions
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- 作者：Matthew A. Brown ; Fernando Vila ; Martin Sterrer ; Stephan Th眉rmer ; Bernd Winter ; Markus Ammann ; John J. Rehr ; Jeroen A. van Bokhoven
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2012
- 出版时间：July 5, 2012
- 年：2012
- 卷：3
- 期：13
- 页码：1754-1759
- 全文大小：305K
- 年卷期：v.3,no.13(July 5, 2012)
- ISSN：1948-7185
文摘
The electronic structures of formic acid (HCOOH) and formate (HCOO鈥?/sup>) have been determined in aqueous solutions over a pH range of 1.88鈥?.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 鈭?.3 eV for deprotonated HCOO鈥?/sup> compared with neutral HCOOH. Such distinction between neutral HCOOH and deprotonated HCOO鈥?/sup> cannot be made based solely on the respective carbon K-edge PEY XA spectra. Independent of pH, the C1s 鈫?蟺* state excitations occur at 288.0 eV and may lead to the incorrect conclusion that the energy levels of the 蟺* 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 蟺* orbitals of deprotonated HCOO鈥?/sup> compared to neutral HCOOH in aqueous solutions.