Journal
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
Volume 14, Issue 1, Pages 357-364Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.jctc.7b00566
Keywords
-
Funding
- NSFC [11290162, 11525520]
- National Key Research and Development Program of China [2016YFA0300901]
- National Basic Research Program of China (973 Program) [2015CB856801]
- Grants-in-Aid for Scientific Research [16K17855] Funding Source: KAKEN
Ask authors/readers for more resources
Free O-H groups of water are often found at the water-hydrophobic medium interface, e.g. for water contact with hydrophobic protein residues, or at the water-air interface. In surface-specific vibrational spectroscopic studies using sum-frequency generation (SFG) spectroscopy, free O-H groups are experimentally well characterized in the O-H stretch region by a sharp 3700 cm(-1) peak. Although these free O-H groups are often defined as the O-H groups which are not hydrogen-bonded to other water molecules, a direct correlation between such non-hydrogen-bonded O-H groups and the 3700 cm(-1) SFG response has been lacking. Our data show that commonly used hydrogen bond definitions do not adequately capture the free O-H groups contributing to the 3700 cm(-1) peak. We thus formulate a new definition for capturing the subensemble of the surface free O-H groups using the intermolecular distance and the angle formed by the water dimer, through the comparison of the similar to 3700 cm(-1) SFG response and the responses from the selected free O-H groups at the HOD-air interface. Using these optimized free O-H group definitions, we infer the fraction of interfacial water molecules with free O-H groups of 28%, a vibrational lifetime of the free OH groups of 1.3 ps, and the angle formed by the free O-H groups and the surface normal of 67 degrees at the water-air interface. We expect that this improved free O-H group definition can be helpful in exploring the structure and dynamics of the interfacial water.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available