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The inelastic neutron scattering from H2 in C24Cs(H2)x has been measured at momentum transfers of 8

Results of detailed structural studies, using elastic neutron scattering, of the freezing of liquid O2 and D2 in porous vycor glass are presented. The experimental studies have been complemented by computer simulations of the dynamics of freezing of a Lennard‐Jones liquid in narrow channels bounded by molecular walls. Our results point to a new simple physical interpretation of freezing in confined geometries.

A novel approach has been followed for synthesizing vertically aligned ZnO nanorods (ZONRs) on indium tin oxide (ITO) coated glass substrates for photovoltaic applications. The fabricated ZONR arrays have been used to construct bulk heterojunction photovoltaic devices together with pristine poly-(3-hexylthiophene) (P3HT) or (6,6)-phenyl C61 butyric acid methyl ester (PCBM) and P3HT blends, respectively. Scanning electron microscopy, X-ray diffraction, photoluminescence, UV-vis absorption spectroscopy, and photovoltaic measurements were performed to study the morphology and device performance of the prepared structures. The typical microstructure of the vertically aligned ZONR arrays plays an important role in collecting the photo-generated electrons and acts as conducting paths to the ITO electrode. Fill factor of the devices increased from 35% to 47% when the PCBM was introduced, which directly contributed to the enhancement of the power conversion efficiencies up to 1.23%.

We report a comparative neutron scattering study of the molecular mobility and nonexponential relaxation of three structurally similar glass-forming liquids, isopropanol, propylene glycol, and glycerol, both in bulk and confined in porous Vycor glass. Confinement reduces molecular mobility in all three liquids, and suppresses crystallization in isopropanol. High-resolution quasielastic neutron scattering spectra were fit to Fourier transformed Kohlrausch functions exp[-(t∕τ)(β)], describing the α-relaxation processes in these liquids. The stretching parameter β is roughly constant with wavevector Q and over the temperature range explored in bulk glycerol and propylene glycol, but varies both with Q and temperature in confinement. Average relaxation timesτ(Q)are longer at lower temperatures and in confinement. They obey a power lawτ(Q)∝ Q(-γ), where the exponent γ is modified by confinement. Comparison of the bulk and confined liquids lends support to the idea that structural and∕or dynamical heterogeneity underlies the nonexponential relaxation of glass formers, as widely hypothesized in the literature.

Magnetic properties of Fe nanoparticles with different sizes synthesized by a physical deposition technique have been investigated experimentally. We have used a high pressure sputtering technique to deposit iron nanoparticles on a silicon substrate. The nanoparticles are then analyzed using atomic force microscopy (AFM), transmission electron microscopy (TEM), and superconducting quantum interference device techniques. TEM and AFM data show that the particle size could be tuned by adjusting the deposition conditions. The magnetic properties have been investigated from temperature dependent magnetization M(T) and field dependent magnetization M(H) measurements. The results show that two phases including both ferromagnetic and superparamagnetic particles are present in our system. From these data we extracted the superparamagnetic critical size to be 9 nm for our samples. Ferromagnetic particles are single magnetic domain particles and the magnetic properties can be explained by the Stoner and Wohlfarth mo...

We report measurements of the local free volume and mobility of a glass-forming liquid (glycerol) confined in a mesoporous silica glass. The lower molecular mobility in confinement, measured by neutron scattering spectroscopy, is accompanied by a higher mean free volume size between molecules, measured by positron annihilation lifetime spectroscopy. The confined liquid appears to be perturbed to such an extent that the normally observed free volume/mobility relationship is reversed. This study shows that these effects originate locally at a molecular level.

A sensitive temperature dependence of the optical rotatory power of a cholesteric liquid‐crystal film in the vicinity of the smectic‐A phase is reported. The results are consistent with the pretransitional unwinding of the helical structure. The use of the effect in thermometry is discussed.

An interface to a Biomation 1010 transient recorder has been built with hardware and software sufficiently general for use with any computer which is based on the 6052 microprocessor.