Atomically ordered PdAgH and PdCuH hydrides synthesized in an atmosphere of gaseous hydrogen at P = 3 GPa were studied by inelastic neutron scattering. The results showed a large difference between the Pd-H, Ag-H and Cu-H interactions. Values of 93 and 116 meV were predicted for the local H vibrations in dilute Ag-H and Cu-H solid solutions.

Inelastic incoherent neutron scattering measurements on the hdaice, ice Ih and high-pressure phases ice VI and ice VIII revealed similarity between the amorphous phase and crystalline ice VI and led to the new proposition that hda ice consists of two interpenetrating hydrogen-bonded networks with no hydrogen bonds between “sublattices”.

Inelastic neutron scattering methods were used in conjunction with Raman spectroscopy to probe the vibrational density of states of the hydrofluorocarbons (HFCs) 134 (HF2C-CF2H) and 134a (F3C-CFH2) adsorbed in the cages of dehydrated Na-X zeolite. A comparison of the vibrational spectra of the encaged HFC species with those of their gas-phase analogs indicates that the HFCs adsorb nondissociatively at room temperature and are most likely associated with Na cations in the supercages at the SIII sites. Guest-host interactions are manifested by adsorption-induced perturbations of the gas-phase torsional and C-H stretching vibrations and the presence of additional features presumably due to low-energy whole-molecule vibrations and adsorbate-coupled zeolite framework vibrations. Moreover, although the 134 trans conformer is favored by 5 kJ/mole in the gas phase at 300 K, the gauche conformer seems to be more prevalent in the zeolite at this temperature and below. This suggests that a sizeable fraction of the Na-X adsorption sites provides a stabilizing configuration for the otherwise higher-energy gauche conformation, perhaps due to hydrogen-bonding interactions with the zeolite framework.

A classic problem in polymer science is the preferential adsorption at a solid interface of one polymer species from a multi-component fluid mixture. Prototype systems for studying this selective adsorption process are solutions consisting of alkane molecules of two different lengths in the presence of a solid interface. Before neutron diffraction could be used to probe structural questions related to the selective adsorption process in such systems, a significant effort was required to develop methods for fabricating suitable samples. We describe techniques for preparing samples of long-alkane monolayers adsorbed on exfoliated graphite by adsorption from solution and by deposition from the vapor phase.

Inelastic incoherent neutron-scattering spectra of cis-, trans- and Na-doped polyacety-lene are presented. The experiments were performed with time-of-flight and filter-analyzer spectrometers on stretch-oriented samples such that the polarization of vibrational modes could also be determined.

Quasielastic neutron scattering measurements of [Ni(NH3)6](N03)2 were made with two different resolutions of ca. 140 and 30 μeV. The following suggestions are analyzed:

1. The NH3 rotational diffusion model is more adequate than NH3 120° jump model.

2. Some NH3 groups slow down whereas some rotate rapidly.

3. There exists an additional QNS component close to the phase II/phase III transition.

Above To = 196 K, white phosphorus, a solid composed of P4 molecules, exhibits a plastic crystal phase. Below this temperature, the structure is triclinic and orientationally ordered, with six molecules in a unit cell. Using inelastic neutron scattering on a polycrystalline sample, observations were made of the rapid reorientational motions above To, and the librational modes below To. In addition, neutron powder diffraction was used to investigate the crystal structures above and below To.

Inelastic neutron scattering measurements of the atomic momentum distribution, the atomic kinetic energy and other single atom properties in quantum liquids and liquid neon are presented. The data were taken on the MARI instrument at ISIS and analyzed using a new method. The measurements have sufficient precision to show that n(k) in a normal Bose liquid differs significantly and unambiguously from the classical, Maxwell-Boltzmann distribution. The final state broadening function is also extracted from the data and found to be similar in liquid 3He and 4He.