Hydrogen bonds (H-bonds) can be interpreted as a classical electrostatic interaction or as a covalent chemical bond if the interaction is strong enough. As a result, short strong H-bonds exist at an intersection between qualitatively different bonding descriptions, with few experimental methods to understand this dichotomy. The [F-H-F]−ion represents a bare short H-bond, whose distinctive vibrational potential in water is revealed with femtosecond two-dimensional infrared spectroscopy. It shows the superharmonic behavior of the proton motion, which is strongly coupled to the donor-acceptor stretching and disappears on H-bond bending. In combination with high-level quantum-chemical calculations, we demonstrate a distinct crossover in spectroscopic properties from conventional to short strong H-bonds, which identify where hydrogen bonding ends and chemical bonding begins.
- Award ID(s):
- 1609044
- PAR ID:
- 10090791
- Date Published:
- Journal Name:
- Physical Chemistry Chemical Physics
- Volume:
- 20
- Issue:
- 24
- ISSN:
- 1463-9076
- Page Range / eLocation ID:
- 16414 to 16427
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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