It is argued that the frequency and temperature dependence of atomic fluorescent light scattering from gases provides information concerning the energy curves and dipole matrix elements as a function of separation.

For Pd containing 30 ppm Fe, and for Au containing 0.2% Gd, we have found a thermal boundary resistance that is approximately proportional to $T^{-1\mathrm{}}$ below 20 mK. The improvement in heat transfer is, at 4 mK, a factor of 50 for the Pd sample and a factor of 20 for the Au sample over that expected for phonon conduction in the same samples. The mechanism for thermal transfer is thought to be a direct coupling between the magnetic moments of the impurities and the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ nuclei.

The radial electron temperature profile of a hydrogen plasma column is controlled by electron-cyclotron resonance heating. With the use of this technique the stabilizing effect of the electron temperature gradient on collisionless drift instabilities is checked experimentally.

We have done an experimental study of low-frequency waves in a low-$\beta$ plasma confined in a hexapole with and without toroidal field. The identification of the waves and the interpretation of mode transition in poloidal mode number are made in comparison with the results predicted from linear theory with slab geometry.

The anomalous heating and momentum transfer in a current-carrying plasma are calculated including the effects of ion resonance broadening on the nonlinear development of the ion acoustic instability. In the constant-current regime, the anomalous resistivity is found to be of order ${\left(\frac{T_i}{T_e}\right)}^{\frac{3}{2}}{{\omega }_{\mathrm{pe}}}^{-1\mathrm{}}$, which compares favorably with the measured resistivity in several experiments.

It is argued that the electrical conductivity due to Bjerrum and ionic defects in ice can be calculated by considering all possible closed paths taken by ionic or Bjerrum defects in the lattice in which each bond is retraced. Using this method, it is argued that the Hall effect due to such defects should be zero at low temperatures.

A computer study of a tetrahedrally coordinated random-network structure is reported as a model for amorphous Si or Ge. A previous model is refined to produce equal near-neighbor distances; it is more carefully statistically characterized and the coordinates of each individual atom are now known. The radial distribution function has been obtained to greater precision and to a greater radial distance; it compares well with experiment.

The effect of crystal-field levels on the elastic constants has been measured for the singlet ground-state system PrSb. The results can be accounted for quantitatively. Elastic-constant measurements in double-hexagonal close-packed Pr reveal also strong crystal-field effects.

Electron-paramagnetic-resonance studies of the "one-dimensional" metal-chain compound Magnus's green salt, ${\mathrm{P}\mathrm{t}\left(\mathrm{N}{\mathrm{H}}_3\right)}_4$Pt${\mathrm{Cl}}_4$, has revealed the presence of localized hole states having an axial resonance with $g_{\parallel }=1.939\mathrm{}\pm 0.002$ and $g_{\perp }=2.504\mathrm{}\pm 0.002$. These states have been identified as bound $d_{z^2}$-like states associated with a $d_{z^2}$-like valence band. From the observed hyperfine pattern we infer that the holes, although localized, have orbits extended over several Pt sites along the chain. We show how the states can be introduced in a series of doping experiments with Magnus's green salt powders.

We have measured $X$ rays from 30-MeV Cl beams on various solid targets between carbon and copper. The ratio of double $K$-shell to single $K$-shell vacancy production in Cl exhibits a broad peak near $Z=20\mathrm{}$ (Ca). This behavior is not predicted by Coulomb ionization. This peaking is examined using a molecular-orbital mechanism. To explain the results both $K$-shell electrons must be promoted to the vacant orbitals of the Cl beam. This is the first evidence of double $K$-shell promotion.

Cyclotron resonance heating is used to produce hot ($T\approx 250$ keV) electrons with $\beta$ up to 10% in an axisymmetric torus. The plasma pressure is nearly isotropic. Confinement times of several seconds are achieved, limited by collisions with background gas. Plasma stability is described.

We present measurements of collisionless spatial cyclotron damping rates and finite minimum wavelengths near resonance. The plasma density and temperature are determined from wavelength data by solving the hot-plasma dispersion relation far away from and near cyclotron resonance. Damping rates determined from resulting plasma parameters agree with the experimentally determined damping rates as well as with those obtained from Langmuir-probe data.

The torque on a Rayleigh disk in dc helium II counterflow produced by a heater has been measured over the range 0.969 K to $T_{\lambda }$. We find that the response of the disk is approximately the same for normal fluid and superfluid. A torque deficit of ≈ 50% of that from potential-flow theory appears to be explainable in terms of turbulent, supercritical flow in the channel, rather than anomalous disk behavior. These findings are in contradiction to a number of other studies involving net mass flow relating to the "$\lambda$-point anomaly" of Pellam.

Superconductor-insulator-superconductor ($S-I-S$) and $S_1-I-S_2$ tunnel junctions have been studied with the thin-film electrodes in a dilute vortex state, at temperatures such that the tunneling is predominantly due to the vortex-core excitations. We conclude that the vortex cores in the upper film lie on top of those in the lower film, but that the net tunneling transition probability between vortex-core states is very much smaller than usual tunneling probabilities.

In their recent work using the renormalization-group approach, Fisher, Ma, and Nickel derived results for $\eta$ when there is a long-range interaction, ${\mathcal{r}}^{-d-\sigma }$, which were seemingly at variance with the numerical results of Nagle and Bonner. The problem is the presence of nonthermodynamic terms in the spin-spin correlation function which never-theless contribute to the thermodynamics. We also find that the scaling relation between $\delta$ and $\eta$ fails to hold for $d>\mathrm{}2\mathrm{}\sigma$.

We have measured the surface electron density and the magnetic field dependence of the extremes of the oscillatory quasiparticle $g$ factor in a two-dimensional electron gas.

Magnetic-anisotropy measurements show evidence for the existence of crystal-field splitting of the transition-metal ion in zinc-manganese single crystals. Assuming the manganese ion has a spin value of 2, the maximum energy splitting $\Delta$ is 0.3°K. On the condition that $\frac{\Delta }{T}$, $\frac{T_{\mathrm{K}}}{T}<1\mathrm{}$, the Kondo behavior as indicated by the experimentally measured magnetic susceptibility is not seriously affected.

A sensitive Rayleigh-scattering technique has been developed which combines the advantages of stimulated and classical scattering. Forward Rayleigh scattering (3-mrad angular separation) in NaF was observed between 300 and 20°K. The scattered intensity varies by more than 4 orders of magnitude within this temperature interval. Quantitative agreement with theoretical values based on the Landau-Placzek theory is found for $T>\mathrm{}80\mathrm{}°$K. Scattering rates considerably larger than expected are found for lower temperatures.

We present an x-ray photoemission spectroscopy study of the rare earths La, Ce, Pr, and Nd. We show that the spectra of these metals in the vicinity of the Fermi energy account for the $4f$ levels as well as for the valence states. The energy location of the $4f$ electrons is in fairly good agreement with an existing computation performed in the framework of the renormalized-atom method.

The generation of second-harmonic ultrasound (5 to 10 MHz) with an estimated conversion efficiency ≳ 20% has been observed for the soft shear mode in ${\mathrm{V}}_3$Si below 77°K. The harmonic generation is a manifestation of the unusually large shear anharmonicity for this unstable compound; however, static symmetry arguments forbid the generation of an even-ordered harmonic for a high-symmetry shear wave in a cubic crystal. Several possible sources of symmetry reduction are discussed.