TY  - JOUR
A1  - Kirchberg, Henning
A1  - Nalbach, Peter
A1  - Bressler, Christian
A1  - Thorwart, Michael
T1  - Spectroscopic Signatures of the Dynamical Hydrophobic Solvation Shell Formation
T2  - The Journal of Physical Chemistry B
N2  - When a hydrophilic solute in water is suddenly turned into a hydrophobic species, for instance, by photoionization, a layer of hydrated water molecules forms around the solute on a time scale of a few picoseconds. We study the dynamic buildup of the hydration shell around a hydrophobic solute on the basis of a time-dependent dielectric continuum model. Information about the solvent is spectroscopically extracted from the relaxation dynamics of a test dipole inside a static Onsager sphere in the nonequilibrium solvent. The growth process is described phenomenologically within two approaches. First, we consider a time-dependent thickness of the hydration layer that grows from zero to a finite value over a finite time. Second, we assume a time-dependent complex permittivity within a finite layer region around the Onsager sphere. The layer is modeled as a continuous dielectric with a much slower fluctuation dynamics. We find a time-dependent frequency shift down to the blue of the resonant absorption of the dipole, together with a dynamically decreasing line width, as compared to bulk water. The blue shift reflects the work performed against the hydrogen-bonded network of the bulk solvent and is a directly measurable quantity. Our results are in agreement with an experiment on the hydrophobic solvation of iodine in water.
Y1  - 2019
UR  - https://whge.opus.hbz-nrw.de/frontdoor/index/index/docId/3664
SN  - 1520-6106
VL  - 123
IS  - 9
SP  - 2106
EP  - 2113
ER  -