Back to Search
Start Over
Does the Sum-Frequency Generation Signal of Aromatic C-H Vibrations Reflect Molecular Orientation?
- Source :
-
The journal of physical chemistry. B [J Phys Chem B] 2023 Jun 15; Vol. 127 (23), pp. 5288-5294. Date of Electronic Publication: 2023 Jun 07. - Publication Year :
- 2023
-
Abstract
- Organic molecules with aromatic groups at the aqueous interfaces play a central role in atmospheric chemistry, green chemistry, and on-water synthesis. Insights into the organization of interfacial organic molecules can be obtained using surface-specific vibrational sum-frequency generation (SFG) spectroscopy. However, the origin of the aromatic C-H stretching mode peak is unknown, prohibiting us from connecting the SFG signal to the interfacial molecular structure. Here, we explore the origin of the aromatic C-H stretching response by heterodyne-detected SFG (HD-SFG) at the liquid/vapor interface of benzene derivatives and find that, irrespective of the molecular orientation, the sign of the aromatic C-H stretching signals is negative for all the studied solvents. Together with density functional theory (DFT) calculations, we reveal that the interfacial quadrupole contribution dominates, even for the symmetry-broken benzene derivatives, although the dipole contribution is non-negligible. We propose a simple evaluation of the molecular orientation based on the aromatic C-H peak area.
Details
- Language :
- English
- ISSN :
- 1520-5207
- Volume :
- 127
- Issue :
- 23
- Database :
- MEDLINE
- Journal :
- The journal of physical chemistry. B
- Publication Type :
- Academic Journal
- Accession number :
- 37284731
- Full Text :
- https://doi.org/10.1021/acs.jpcb.3c01225