Low-temperature x-ray-diffraction analysis at ambient pressure shows that the rhombohedral chalcogenides Eu${\mathrm{Mo}}_6$${\mathrm{S}}_8$ and Ba${\mathrm{Mo}}_6$${\mathrm{S}}_8$ transform at 110(5) and 175(10) K, respectively, into a triclinic distorted low-temperature structure. The transitions are presumably due to a Jahn-Teller-type electronic instability arising from the octahedral ${\mathrm{Mo}}_6$ clusters. The absence of superconductivity is attributed to the triclinic deformation of these clusters which leads to a significant splitting of the nearly half-filled Mo $d$-like conduction band.

We provide evidence for a universal relationship between metallic binding energies and lattice parameters. By a simple scaling of a universal relationship, one can obtain binding energies as a function of atomic separation for bimetallic interfaces and bulk metals.

Major controversies over the structure of A1 atoms deposited on the GaAs(110) surface have been resolved by using a first-principles energy-minimization method. The most stable configuration is that of A1 atoms replacing the second layer Ga atoms beneath the surface. At temperatures where this reaction cannot be activated, two important processes are found to exist. In the low-coverage limit, A1 atoms favor twofold sites to form strong bonds with the substrate atoms. At higher coverages, A1 atoms tend to cluster and make new bonds among themselves.

The discovery of open-orbit magnetoresistance peaks in potassium shows that its Fermi surface is multiply connected. A charge-density-wave structure (which would have 24 domain orientations and five open-orbit directions per domain) explains the main features. The magnetic field at which open-orbit peaks appear depends on domain size, which we find to be ∼0.1 mm.

By microwave measurements we have determined the dielectric relaxation rate for adsorbed water in metmyoglobin crystals in the temperature range from 100 to 300 K. The temperature dependence of the dielectric relaxation rate of the adsorbed water is nearly identical to the temperature dependence of the conformational fluctuation rate of the protein as measured by the Mössbauer effect. This surprising correlation may be understood in terms of the mechanical and electrical interactions between the adsorbed water and the protein.

A theory of the condensation of electrons, coupled strongly to optic phonons, into a lattice of real-space electron pairs is presented. Even if the on-site interaction is repulsive, real-space pairing of the Anderson form may occur because of interaction with other sites. Dilution weakens the intersite interaction and causes a phase transition that may be to a metallic state which undergoes $\overrightarrow{\mathrm{k}}$-space (BCS) pairing at low temperatures. The results are applied to $\mathrm{Ba}{\mathrm{Pb}}_{1-x}{\mathrm{Bi}}_x{\mathrm{O}}_3$.

The distribution function $P_L\mathrm{}\left(s\right)\mathrm{}$ of the local order parameter $s$ in finite blocks of size $L^d$ is studied for Ising models for dimensionalities $d=2, 3, \mathrm{and} 4$ by Monte Carlo methods. A real-space renormalization group based on phenomenological scaling yields fairly accurate results for rather small $L$ (e.g., the standard exponents $\beta$ and $\nu$ for $d=3\mathrm{}$ are found as $\frac{2\beta }{\nu }=1.03\mathrm{}\pm 0.01$, $\frac{1}{\nu }=1.60\mathrm{}\pm 0.05$). The method can easily be generalized to arbitrary Hamiltonians, including spin dimensionalities $n>\mathrm{}1\mathrm{}$.

We have measured the distribution in current for the onset of voltage in small-area Josephson junctions for temperatures down to ∼1.6 K. The lifetime of the $〈V〉=0\mathrm{}$ state for our highest current density junctions becomes temperature independent for $k_{\mathrm{B}}T\lesssim \frac{\hslash {\omega }_0}{20}$, a $T$ much less than the WKB prediction (${\omega }_0$ is the junction resonant frequency). This is consistent with the Caldeira-Leggett theory, which includes damping effects on the quantum tunneling rate.

An exactly solvable model of an interface between coexisting phases in a modified planar lattice gas, or its magnetic equivalent, is described. The results reconcile the apparent conflict between intrinsic structure and capillary fluctuation theory. There are anomalously long-ranged correlations in the interface.

We formulate a model in which a light pointlike composite fermion is obtained dynamically from two heavy relativistic constituents bound by strong, short-range forces with the bound-state mass as low as one-tenth the sum of the constituent masses, while still obtaining the correct Dirac moment for this bound state (a factor of 5 greater than that of the constituents). Other static properties and details of the spectrum are investigated.

The electric dipole moment of the neutron (${{\mu }_n}^e$) is calculated in the left-right-symmetic theory of Mohapatra and Pati and related to $\mathrm{CP}$-nonconserving parameters of the neutral kaon system, yielding the bound ${{\mu }_n}^e\gtrsim {10}^{-22\mathrm{}}|{\eta }_{+-}-{\eta }_{00}| e·\mathrm{cm}$. Recent measurements of $K_0\to 2\pi$ amplitudes indicate that ${{\mu }_n}^e$ may well be of order ${10}^{-25\mathrm{}}e·\mathrm{cm}$ which is several orders of magnitude larger than the prediction of the Kobayashi-Maskawa model and only a few times smaller than the current experimental limit ${{\mu }_n}^e\left(\exp \right)<\mathrm{}6\mathrm{}\times {10}^{-25\mathrm{}}e·\mathrm{cm}$.

Data from $\nu N$ interactions in the Fermilab 15-ft bubble chamber show that the mean transverse momentum ($p_T$) of forward hadrons in the hadron c.m. system exceeds that of backward hadrons for $W^2>100\mathrm{}$ Ge${\mathrm{V}}^2$. Events with high ${\pi }_F$, a measure of forward $p_T$, tend to have planar hadron systems and show a three-jet structure in their angular energy flow; their number exceeds that expected in two-jet models. These observations are consistent with quantum chromodynamic predictions of hard-gluon bremsstrahlung.

Inclusive reactions $p+A\to p^{\prime }+X$ are studied at large angles. Binding and Pauli exchange effects are treated in a consistent way. These effects restore the two-body scaling in spite of the orthogonality of the ground and continuum states. Kinematic variables that enter our calculations are very much different from those in the phenomenological analyses. This leads to a very good agreement with the data for light nuclei ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, and ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ at $T_p=500-800\mathrm{}$ MeV, $\theta =180\mathrm{}°-90\mathrm{}°$ with use of one universal one-nucleon momentum density.

We describe a method allowing the extension of Doppler-free spectroscopy to the selection of more than one velocity component of atoms in a gas. This method has been demonstrated experimentally with metastable neon atoms, in a geometry where two velocity components are determined, and transitions in atoms with zero velocity in a plane have been observed.

An evaluation of previously uncalculated finite size effects on the Lamb shift of normal atoms, with use of methods which are well known from muonic atoms, gives corrections which are larger than the experimental uncertainties (40 ppm for the Lamb shift in hydrogen). The additional corrections tend to restore agreement between theory and experiment.

Distributions of electrons emitted when thin carbon foils are bombarded with ${\mathrm{H}}^{+}$ and ${\mathrm{H}}_2^{+}$ ion beams are measured along the forward direction and close to the projectile velocity. The ratio between electron yields per proton for ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}^{+}$ projectiles grows from unity away from the electron peak to a maximum at the peak. This explains the narrower peak widths observed for molecular projectiles. The results are interpreted in terms of a correlated action of the emergent protons on the process of electron transfer to the continuum.

The equilibrium shape of a low-pressure spheromak plasma with a small component of toroidal current carried by finite-gyroradius particles is computed. The stabilizing influence of this current on the tilting mode is determined by employing an energy principle that includes gyroscopic and finite-gyroradius effects.

The angular distribution of low-energy ${\mathrm{K}}^{+}$ ions (250 to 1000 eV) scattered from a W(110) surface is studied as a function of polar angles of incidence and exit for various azimuths with a 127° electrostatic energy analyzer. For specific combinations of polar and azimuthal angles a strong enhancement of the intensity of certain peaks in the energy spectrum is observed which is attributed to focusing of ions scattered in the second layer by the atomic configuration of the first layer.

By using ${\mathrm{D}}_2$ gas as a source of two-dimensional spreading pressure, we have studied the commensurate-incommensurate (C-I) transition in submonolayer Kr on $\mathrm{ZYX}$ graphite at temperatures near 40 K. High-resolution synchrotron x-ray diffraction results show both hysteresis and C-I phase coexistence, clear signatures of a first-order transition. This agrees with theoretical predictions, but apparently gives different behavior from earlier studies at higher temperatures and coverages.

The effective interaction between two ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ atoms in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ is obtained by assuming the ground-state wave function to be a product of pair correlations. It is used to evaluate some of the low-temperature properties of mixtures.