Molecular dynamics calculations on liquid carbon tetrachloride have been used to parameterize atom-atom intermolecular potentials. The resulting models have been used to study the structure and dynamics of the face centred cubic plastic crystal, phase Ia.

Molecular dynamics calculations for the liquid and cubic plastic crystal phases of carbon tetrachloride

Sum frequency generation spectroscopy has been used to obtain the vibrational spectrum of HCl on the surface of a liquid. HCl was studied on the surface of 96 wt % H2SO4, 12 M HCl solution, liquid HCl and glass, of which only liquid HCl produces a resonant signal. Implications for the form of HCl on surfaces and the reactions in the atmosphere are discussed.

https://ase.tufts.edu/chemistry/shultz/abstracts/FirstSpectroscopic.pdf

First spectroscopic evidence for molecular HCl on a liquid surface with sum frequency generation

Infrared and Raman spectra of hydrogen fluoride, deuterium fluoride, and their isotopic mixtures at various temperatures from 293 to 77 K have been recorded and analyzed in comparison with calculated data obtained from the classical G.F. matrix method applied to hypothetical structures chosen a priori. The best fit lead to the most probable structure of HF at 293 K which is a zig–zag chain with six or seven molecules having an angle of 42° with the average axis. At a lower temperature (190 K), just before solidification, the chains become longer, n=8 with an angle θ≂35 °. These structures fit well with the high dielectric constant of liquid hydrogen fluoride and lead to a calculated Kirkwood factor g1=3.65 at 293 K and g1=5.36 at 190 K which are in perfect agreement with known experimental values.

Structure of liquid hydrogen fluoride studied by infrared and Raman spectroscopy

The ab initio crystal orbital method including electrostatic long range corrections has been applied to determine the equilibrium structure of the infinite bent chain of hydrogen fluoride molecules using extended gaussian basis sets ranging from double zeta to a near Hartree-Fock limit quality. Electronic band structure, hydrogen bond energy and dipole moment are reported as well. A sufficiently large number of points has been computed with the double zeta basis to determine an almost complete force field. With the larger basis sets the most important force constants have been reevaluated. From these force constants the optically active vibrational frequencies, phonon dispersion curves, phonon density of states and zero point energy have been derived within the framework of the harmonic approximation.

AB initio studies on hydrogen bonded chains. II. Equilibrium geometry and vibrational spectra of the bent chain of hydrogen fluoride molecules

Raman and infrared spectra were recorded for crystalline deoxycytidine samples at 300, 200, 100 and 10 K. Data were taken over the spectral range 20–4000 cm−1. The wavenumbers of most vibrational modes were found to increase as the temperature was lowered. A number of peaks split into multiplets at low temperature. A new mode, observed at 375 cm−1, is a marker band for 2′-deoxyribose in cytosine-containing nucleic acids. Evidence is presented supporting the assignment of marker bands associated with the C3′-endo and C2′-endo puckers of deoxyribose. No clear indication was found of any structural phase transitions in this temperature range. Several hydrogen-stretching modes were found to involve hydrogen bonding. Plausible assignments of all the main features observed are suggested. Copyright © 2003 John Wiley & Sons, Ltd.

Temperature-dependent Raman and infrared spectra of nucleosides. II?Cytidine

Raman and far infrared spectra of the solid phases of carbon tetrachloride

Raman spectra of crystalline HF and DF

Raman and infrared spectra of polycrystalline samples of HCl, HBr, HI, HF and their deuterated analogues are briefly reviewed and correlated with crystal structures and molecular properties. A simple force constant model is used to describe the vibrations of these crystals in their low temperature ordered phase and to obtain estimates of their hydrogen bond strenghts.

Raman and infrared studies of the hydrogen halide crystals

Raman and infrared spectra of the three phases of crystalline HI and DI have been recorded, and mode frequencies corresponding to molecular vibrations, librations and translations are identified. A comparison with the spectra of solid HCl and HBr confirms that only the low temperature phase has an ordered structure. A simple force constant model is described which is used to assign the observed frequencies for this phase.

W. S. Tse

Papers

Raman and far infrared spectra of the solid phases of carbon tetrachloride

Raman spectra of crystalline HF and DF

Raman and infrared studies of the hydrogen halide crystals

Raman and infrared spectra of crystalline hydrogen iodide and deuterium iodide