Deciphering spectral signatures of proton delocalization in complexes of hydroxide and hydronium ions with water molecules
- Special MP Department Seminar
- Date: Apr 2, 2025
- Time: 02:30 PM - 03:30 PM (Local Time Germany)
- Speaker: Prof. Anne McCoy
- University of Washington, Department of Chemistry, Seattle, USA
- Location: Building K, Haber-Villa, Faradayweg 8, 14195 Berlin
- Room: Seminar Room
- Host: Department of Molecular Physics

One class of system where explorations of
larger complexes is particularly instructive involves complexes of ions with
water molecules. In these systems the
cooperative nature of the hydrogen bond that are formed leads to large changes
in the strengths of the ion-water interactions as more water molecules are
introduced, and this, in turn, has a large effect on the spectroscopy. This talk will focus on work in our group
exploring the most fundamental ion-water complexes, those between water
molecules and hydronium or hydroxide ions.
This work employs an array of theoretical and computational approaches,
ranging from analysis of the couplings of the vibrations at the harmonic level
through analysis of the wave functions using diffusion Monte Carlo
approaches. The work is motivated by the
studies of the vibrational spectra of complexes of hydronium and hydroxide ions
with up to five water molecules.
Interestingly, as the number of solvating water molecules is increased
from one to three, the frequency of the OH bond involved in the ion/water
interaction experiences a large blue-shift with very similar spectral contours
being observed for the complexes of hydroxide and hydronium ions with water.