J. Schiffer

VIBRATIONAL DYNAMICS IN LIQUID WATER: A NEW INTERPRETATION OF THE INFRARED SPECTRUM OF THE LIQUID.

In comparing the infrared spectra of liquid water and simple hydrates, two anomalies are noted which are apparently inexplicable in terms of presently acceptable theories of the liquid. These anomalies are explained in terms of a Maxwellian distribution of collisional interactions between water molecules, which when put in quantitative form reveals (1) that most molecules in the liquid are highly distorted by collisional perturbations, and (2) that there is a broad distribution of distortion among the molecules in the liquid. When translated into vibrational dynamics, these concepts lead to a continuum distribution of ν1 and ν3 modes of varying distorted molecules. It is shown that in its stretching motion, liquid water behaves dynamically as a continuum of OH bond oscillators of different frequencies, demonstrating both weak inter‐ and intramolecular vibrational interactions. A new interpretation of the infrared spectrum of liquid water is given in terms of this model, and other spectral evidence is offe...

The FS correlation and a systematic analysis of the stretching absorptions of water in the condensed state

The separation between uncoupled ν3 and ν1 frequencies of water symmetrically bound in both nonaqueous solvents and hydrates has been shown to vary linearly with the HOD stretching frequency of water, for both H2O and D2O. This relation, the FS correlation, has been explored theoretically and it has been shown to be useful for estimating geometry changes of water in hydrates, upon deuteration. It is also useful in determining the effect of cation coordination on the stretching frequencies of water molecules. A method is also developed, using this relation, for systematically analyzing the origin of the stretching bands of water in condensed systems.

Intra‐ and Intermolecular Interactions in and between Water Molecules in Calcium Sulfate Dihydrate

A study of the infrared spectra of varyingly deuterated thin films of gypsum has afforded information on the relative importance of intra‐ and intermolecular interactions in determining the stretching bands of water in the spectrum. This study has indicated that the internal forces in water are different for water in gypsum than they are for water in the vapor. It is further indicated that the water molecule in gypsum is much like the average molecule expected to exist in the liquid state.

INTRAMOLECULAR INTERACTIONS IN THE WATER MOLECULE: THE STRETCH--STRETCH INTERACTION FORCE CONSTANT OF WATER MOLECULES IN HYDROGEN-BONDED SYSTEMS.

A calculation is described for determining water molecule Frr force constants from observed HOD, H2O, and D2O vibrational frequencies. The calculations for water in the vapor and in the hydrates MnCl2·2H2O, FeCl2·2H2O, CoCl2·2H2O, and CuCl2·2H2O indicate a large increase in Frr with hydrogen bonding. Various contributions to Frr are considered, and its increase is attributed to an enhancement of the effective charge on water hydrogens with increased hydrogen bonding.

Vibrational Analysis of Copper Chloride Dihydrate

Room‐ and low‐temperature infrared spectra of copper chloride dihydrate and its deutero modifications have been obtained, as well as polarized spectra of oriented polycrystalline films of the hydrate. Bands due to vibrations of H2O, D2O and HOD molecules in the hydrate, as well as their polarization, are considered in terms of the crystal structure and previous interpretations of the vibrational bands of the solid.

Intermolecular Coupling of Water Molecules in Copper Chloride Dihydrate

Polarized and unpolarized infrared spectra have been obtained for copper chloride dihydrate samples, containing low mole ratios of H2O and D2O. The positions of the absorption bands of these samples are shown to differ from those of samples, containing high percentages of these same molecules. The spectral differences noted are shown to be related to the interactions between water molecules in the solid. Furthermore, a criterion is provided for sensing a variation of hydrogen bond strength with deuteration, and the origin of bands in the ν2 overtone regions of H2O, D2O, and HOD is also considered.

Intramolecular forces in the water molecule in lithium sulfate monohydrate

A study of the low−temperature infrared spectra of varyingly deuterated mulls of lithium sulfate monohydrate has afforded information on the origin of bands due to the vibrations of the water molecule in the solid. Assignments are made for the intermolecularly uncoupled modes which produce these bands in the spectrum and intramolecular coupling force constants are calculated.

Intermolecular forces involving the water molecules in lithium sulfate monohydrate

A study of the low‐temperature infrared spectra of varyingly deuterated mulls of lithium sulfate monohydrate has afforded information as to the nature of vibrations of water molecules causing infrared absorptions. Using intra‐ and intermolecular force constants, obtained from the data of doublet spectra, spectra of intermolecularly coupled species were predicted and compared with experiment. The agreement between calculated and observed spectra is good, but not perfect. This indicates that nonneighbor interactions are weak but significant in determining the nature of the stretching modes involving water molecules in Li2SO4⋅H2O. Furthermore, it is shown that the intermolecular interactions involving water molecules are mostly dipolar in origin.