The chemisorption of hydrogen on metals is treated by a self-consistent calculation. Three-dimensional charge densities, interaction energies, and dipole moments are given as a function of position of the hydrogen adatoms. The results are compared with experiment. The experimental picture of a dissociated adsorbate of small dipole moment is substantiated, and the calculations are consistent with the observation that hydrogen field desorbs together with the surface atoms of the substrate.

We have developed a model for the interaction of ions with insulator surfaces. This model describes in detail the processes whereby ions of different ionization potentials are neutralized at the surface and predicts that ion bombardment can cause impurity-ion migration in such films, depending on ionization potential. Such migration is demonstrated to occur, in agreement with the model, by use of radiotracer techniques employing ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ deposited on Si${\mathrm{O}}_2$ films.

We present acoustic-attenuation experiments at frequencies up to 1000 MHz in the vicinity of the Néel point of Mn${\mathrm{F}}_2$. They show that the attenuation is maximum in the low-temperature phase near the transition, and the temperature at which that maximum appears decreases as the frequency increases. A brief scanning of the theory is given which explains this new effect in terms of relaxation of staggered magnetization.

We discuss a constraint put by the $E2\mathrm{}$ transition systematics in the $1f-2p$ shell on the effective two-body interaction in the shell. Some simple modifications in the Kuo-Brown effective interaction are made which tend to make it satisfy this constraint.

We report measurements of the inclusive electroproduction reactions $e^{-}+p\to e^{-}+{\pi }^{\pm }+X$. The measurements were made at two data points with the same value of the Bjorken scaling parameter, $\omega =4.1\mathrm{}$, and with $Q^2$ values of 1.20 and 2.02 Ge${\mathrm{V}}^2$. The virtual-photo-production cross sections are studied as a function of missing-mass variables and Feyn-man scaling variables. The results suggest a simple scaling behavior.

We have measured angular distributions for single photoproduced ${\pi }^{+}$ mesons at 4.0-, 5.0-, and 7.5-GeV incident photon energies and at lab angles from 11° to 66° with the Stanford Linear Accelerator Center 8-GeV spectrometer. Combined with previous Stanford Linear Accelerator Center results, this gives complete angular coverages for this range of energies. The data show the usual "$t$" and "$u$" diffraction peaks and a "central plateau" region dropping as $S^{-7.3\mathrm{}}$.

We show that the form factors of the strangeness-changing current are renormalized in first order, rather than second order, in the symmetry-breaking parameters if the chiral symmetry is realized by Nambu-Goldstone bosons. The first-order renormalization is explicitly calculated for the meson and baryon form factors.

We have recorded the x-ray emission spectrum of ${\mathrm{N}}_2$, and resolved and identified the lines corresponding to the three outermost valence orbitals. We have observed vibrational fine structure within these x-ray emission lines.

Coincidence measurements made of $L_{2,3}M$ x-ray yield versus scattered-ion final charge state in differential ${\mathrm{Ar}}^{+}$ -Ar scattering at keV energies are compared with theoretical fluorescence-yield calculations by Bhalla and Walters and by Larkins. Enhancement of the fluorescence yield at ${\theta }_{\mathrm{lab}}={20}^{\circ }$ is found for energies of 20 keV and above due to excitation of the Ar $M$ shell.

The photoionization cross section for Ar I is calculated from threshold to 50 eV by means of many-body perturbation theory. Good agreement is obtained with the experimental data of Madden, Ederer, and Codling, including resonances. It is found that a low-order calculation is adequate.

The accuracy of data obtained by field-ion microscopy is often limited by a ± 15% uncertainty of converting measured voltages into field strengths. Plotting the difference of relative energy deficits of free-space ionized ${\mathrm{H}}_2$, ${\mathrm{D}}_2$, or Kr for sets of two applied voltages against the logarithm of the voltage ratios yields a field factor $k$. The surface field $F_0=\frac{V}{k{r}_t}$ is obtained with the 3% accuracy by which the tip radius $r_t$ can be known. The method is applicable to all metals accessible to field-ion-microscopy.

We have observed the linear coupling between an electrostatic ion cyclotron wave and an ion acoustic wave near the second-harmonic ion cyclotron frequency for propagation of an electrostatic ion wave along a magnetic field, where the wave number perpendicular to the magnetic field $k_{\perp }$ exists.

The saturation amplitude of a nonlinearly excited plasma oscillation is calculated, taking into account both the frequency-mismatch effect due to relativistic correction and the effect of collision damping. It is explicitly shown, even in cases where the collision frequency $\nu$ may be considered extremely small, how the inclusion of $\nu =0^{+}$ leads to a qualitative change in the asymptotic behavior of the system.

Peaks have been observed in the attenuation of zero sound at the "$A$" and "$B$" transitions below 3 mK in liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. In a magnetic field the $A$ transition splits, exhibiting two narrow attenuation peaks. The attenuation peak at the $B$ transition seems to result from scattering localized at the interface between the two liquid phases.

The continuation of the $n$-vector model to negative values of $n$, the number of internal degrees of freedom, provides exact results for $n=-2\mathrm{}$ and arbitrary dimensionality $d$: The free energy and two-point correlation function take their noninteracting values.

A NMR technique, which consists of a superposition of (i) a Waugh-type multiple 90° rf pulse sequence removing dipolar interactions, (ii) a pulsed magnetic-field-gradient sequence, and (iii) a relatively slow Carr-Purcell train of 180° pulses is used to determine translational self-diffusion coefficients in liquid crystals where the classical NMR technique fails because of too short a $T_2$.

An anomalous shift of the onset of interconduction-band optical absorption in copperaluminum alloys gives precise values for the direct and indirect energy band gaps, setting the upper-$Q_{+}$ band profile in pure copper in the Fermi-surface-neck region of $k$ space. In addition, it establishes the range of validity of a direct-transitions model. A consistent pattern of behavior is suggested among copper-based alloys with polyvalent solutes.

The coherent-potential approximation (CPA) is generalized to include two bands with band mixing and is applied to the excitonic doublets of mixed crystals of alkali and cuprous halides. These systems are almost an ideal testing ground for the two-band CPA; most of the parameters needed to predict peak positions, intensity ratio, and linewidths, for an arbitrary composition, are known from independent experiments. Agreement between CPA calculations and experiments is very encouraging.

The spin-wave excitations for nickel have been measured at a series of temperatures between 4.2 and 715°K. It is found that the spin waves change very little in character even at 80° above the Curie point. A sudden decrease in the spin-wave intensity at about 80 meV, interpreted as the intersection of the spin-wave spectra with a continuum band of Stoner excitations, is also found to be quite temperature independent.

The critical behavior for $T>\mathrm{}{T}_c$ and $H=0\mathrm{}$ of ferromagnets with both isotropic exchange coupling and dipolar interactions is studied by exact renormalization-group techniques in $d=4-\epsilon$ dimensions ($\epsilon >0\mathrm{}$) with ($n=d$)-component spins. A crossover from short-range isotropic (Heisenberg) to characteristic dipolar behavior occurs. The asymptotic spin-spin correlation function develops a factor ${\delta }_{\alpha \beta }-\frac{q^{\alpha }{q}^{\beta }}{q^2}$ which suppresses longitudinal fluctuations. Experiments on EuO and EuS are considered.