Raman spectroscopic study of dilute HOD in liquid H2O in the temperature range − 31.5 to 160 °C

Abstract

Articles you may be interested inMolecular dynamics with quantum transitions study of the vibrational relaxation of the HOD bend fundamental in liquid D2O Polarized Raman spectra for the full range of isotopic dilution for ice Ic and amorphous ice: Mixtures of intact H2O and D2OWe present Raman data for the OD stretch mode of 10 mol % HOD in H 2 0 for the liquid phase from -31.5 to 160 ·C. We find that an exact isosbestic does not hold, but rather the crossing of isotherms slowly but uniformly changes with temperature. We present an analysis based on Boltzmann statistics which gives evidence for a distribution of deuterium hydrogen bond strengths with minimum energy near the frequency (2440 cm -I) also found in the solid ice and amorphous solid phases. This analysis also gives evidence for a band of frequencies above 2630 cm -I due to OD oscillators all at essentially the same high energy relative to the strongest hydrogen bonds, and we interpret this band as due to broken hydrogen bonds. This allows us to calculate hydrogen bond probabilities, and we find this probability increases with decreasing temperature and approaches a value equal to the four bonded percolation threshold near the singular temperature Ts"" -45 ·C for the anomalies of supercooled water. Peak frequency and full width at half-maximum of the OD stretch band are found to drop precipitously to the amorphous solid values as T -+ Ts implying the ultimate state of supercooled water is similar to the amorphous solid.6954

Order and correlation contributions to the entropy of hydrophobic solvation

“…It has been argued elsewhere that the only hydrogen bond model consistent with the heat capacity of water is that of Hare and Sorenson. 67 We have been unable to find a hydrogen bond model that captures both hydrophobic solvation entropy and bulk water thermodynamics. The information and scaled particle theories are based on simulated water properties at small scales and experimental properties at large scales.…”

“…The few calculations attempted here do not represent the total spread in ∆G H B and ∆S H B if all combinations of HB free energy parameterisations and HB geometry definitions were compiled. The parametrization of Hare and Sorensen, 67 though consistent with the heat capacity of water, significantly underestimates the hydrophobic solvation entropy. The choice of HB models corresponds to a sufficiently wide range of free energies that it amounts to a fit, though no single HB model that we are aware of is consistent with both bulk and solvation properties.…”

“…We select some of the popular choices of HB free energy: the Muller two-state model, 39 the recent re-parameterisation by Suresh and coworkers, 42 and the parameterisation by Hare and Sorensen from Raman spectroscopy 67 that was noted to be the only parametrization to be consistent with the heat capacity of water. 40 For these choices of HB free energies, we count the hydrogen bonds in our simulations using the Luzar and Chandler 44 and the Godec and Merzel 18 definition of hydrogen bonds and calculate the free energy.…”

Ultrafast Energy Transfer in Water−AOT Reverse Micelles

“…A linear scaling is allowed because the optical density varies linearly with the water temperature, as is evidenced from the temperature dependence of the linear absorption spectrum. 9,[11][12][13] The calculated maximum temperature jump is ~50 K for the largest micelles ( ), which shows that for this size practically all the excess vibrational energy is completely thermalized over the water 35 w 0 = droplet within ~2 ps. This is a direct consequence of the fact that for large micelles the heating occurs much faster than micelle cooling.…”

The relation between the structure of the first solvation shell and the IR spectra of aqueous solutions

“…It is generally believed that the distinctive behavior of water arises from the underlying hydrogen bond network [3,4]. While the nature of aqueous hydrogen bonds has been under considerable debate in the literature, their spectroscopic signatures have been well documented [5][6][7]. The red shift of the O-H stretch upon condensation is a prime example.…”