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Updated: Mar 14, 2026
16:24
Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
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Structure Making and Breaking Effects of Cations in Aqueous Solution: Nitrous Oxide Pump-Probe Measurements
J Shattuck1, P Shah1, S Erramilli2
1Department of Chemistry and the Photonics Center, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
The Journal of Physical Chemistry. B
|September 27, 2016
Summary
Ultrafast IR spectroscopy reveals how different cations (structure makers vs. breakers) affect water
Area of Science:
- Physical Chemistry
- Spectroscopy
- Solution Chemistry
Background:
- Aqueous salt solutions contain cations that influence water structure, categorized as structure makers or breakers.
- Understanding ion-water interactions is crucial for solvation dynamics and hydrogen bonding.
- Nitrous oxide (N2O) vibrational modes can probe solvent properties.
Purpose of the Study:
- To investigate the influence of various cations on water hydrogen bonding network using N2O as a probe.
- To correlate cation hydration strength with vibrational energy relaxation and reorientation dynamics.
- To explore salt-dependent perturbations of solvent spectral density.
Main Methods:
- Ultrafast infrared (IR) pump-probe spectroscopy.
- Studied 2 M aqueous solutions of MgCl2, CaCl2, NaCl, KCl, and CsCl at room temperature.
- Analyzed vibrational energy relaxation (VER) and rotational reorientation anisotropy (R(t)) of N2O.
Main Results:
- Observed distinct salt-dependent trends in N2O VER and R(t) decays.
- Results align with cation categorization as structure makers or breakers.
- Evidence suggests cation effects extend beyond the first solvation shell, impacting water's hydrogen bonding network.
Conclusions:
- Cation hydration strength significantly perturbs the water hydrogen bonding network.
- Both coupling strengths and density of states contribute to cation-dependent vibrational energy relaxation.
- Rotational reorientation dynamics correlate with bulk viscosity, unlike previous studies focusing on OH/OD stretches.
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