Water Structure at Aqueous Solution Surfaces of Atmospherically Relevant Dimethyl Sulfoxide and Methanesulfonic Acid Revealed by Phase-Sensitive Sum Frequency Spectroscopy
| Autor: | Heather C. Allen, Xiangke Chen |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Aqueous solution
Hydronium Chemistry Hydrogen bond Inorganic chemistry Photochemistry Methanesulfonic acid Surfaces Coatings and Films chemistry.chemical_compound symbols.namesake Molecular vibration Materials Chemistry symbols Molecule Physical and Theoretical Chemistry Spectroscopy Raman spectroscopy |
| Zdroj: | The Journal of Physical Chemistry B. 114:14983-14988 |
| ISSN: | 1520-5207 1520-6106 |
| Popis: | Interfacial water structures of aqueous dimethyl sulfoxide (DMSO) and methanesulfonic acid (MSA) were studied by Raman, infrared, and conventional and phase-sensitive vibrational sum frequency generation (VSFG) spectroscopies. Through isotopic dilution, we probed bulk water hydrogen bonding strength using the vibrational frequency of dilute OD in H(2)O. As indicated by the frequency shift of the OD frequency, it is shown that DMSO has little influence on the average water hydrogen bonding strength at low concentrations in contrast with an overall weakening effect for MSA. For the water structure at the surface of aqueous solutions, although conventional VSFG spectra suggest only slight structural changes with DMSO and a red shift of hydrogen-bonded water OH frequency, phase-sensitive VSFG reveals more thoroughly structural changes in the presence of both DMSO and MSA. In the case of DMSO, reorientation of interfacial water molecules with their hydrogens pointing up toward the oxygen of the S=O group is observed. For MSA, the interfacial water structure is affected by both the dissociated methanesulfonate anions and the hydronium ions residing at the surface. Both the methanesulfonate anions and the hydronium ions have surface preference; therefore, the electric double layer (EDL) formed at the surface is relatively thin, which leads to partial reorientation of interface water molecules with net orientation of water hydrogens up. Surface DMSO molecules are more effective at reorienting surface water relative to MSA molecules. |
| Databáze: | OpenAIRE |
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