Scattering of light from solids with incident frequency above the band gap is shown to occur as a cascade process in which the electron (hole) makes successive transitions between real states with a small probability of radiative recombination at each step. This gives rise to multiple LO-phonon Stokes-shifted lines in agreement with experimental results.

It is shown how the low-temperature deviations from Matthiessen's Rule observed in a wide variety of dilute nonmagnetic alloys are a consequence of phonon drag in the regime where $\lambda$, the electron mean free path, is determined by electron-impurity scattering [i.e., $g^2{\left(\frac{T}{\theta }\right)}^3\ll {\left(k_{\mathrm{F}}\lambda \right)}^{-1\mathrm{}}$ where $g^2\sim \frac{v_S}{v_{\mathrm{F}}}$]. For a spherical Fermi surface ${\Delta }_T\sim g^2{\left(\frac{T}{\theta }\right)}^3\times {\left(\lambda k_{\mathrm{F}}\right)}^{-1\mathrm{}}\ln \left(\lambda k_{\mathrm{F}}\right)+g^4{\left(\frac{T}{\theta }\right)}^5\ln \left(\frac{{\rho }_0}{{{\rho }_T}^{\mathrm{pure}}}\right)$, where ${\Delta }_T={\rho }_T-{\rho }_0-{{\rho }_T}^{\mathrm{pure}}$ with ${{\rho }_T}^{\mathrm{pure}}$ being the resistivity of the alloy (host) at temperature $T$. For a cylindrical Fermi surface ${\Delta }_T\sim g^2{\left(\frac{T}{\theta }\right)}^3\ln \left(\frac{{\rho }_0}{{{\rho }_T}^{\mathrm{pure}}}\right)$. It is also shown that the singular behavior noted by Mills is spurious.

The lifetime of the 1086-${\mathrm{cm}}^{-1\mathrm{}}$ optical phonon in calcite is measured directly to be 8.5 ± 2 psec at 297°K and 19.1 ± 4 psec at 100°K by using a picosecond laser beam to create the phonons by stimulated Raman scattering, and then observing Raman scattering off the phonons at various delay times with a weaker picosecond beam at another frequency.

The $\overrightarrow{\mathrm{k}}·\overrightarrow{\mathrm{p}}$-APW (augmented-plane-wave) method (extrapolation of energy bands throughout the irreducible wedge of the first Brillouin zone from a set of APW basis states at one point in the wedge) has been applied to TiC. Very poor results are obtained in comparison to those found for PbTe, the material most studied to date using the method. The difficulty appears to be associated with the $d$ bands in TiC and possibly with the sparseness of states at $\Gamma$ for certain rather large energy ranges.

Measurements of the dispersion of magnetic excitons have been made in a single crystal of praseodymium metal using inelastic neutron scattering. A preliminary analysis of the data yields the first detailed information about the exchange interactions and the crystal field splittings in the light rare-earth metals.

The specific heat of YbFe${\mathrm{O}}_3$ in the range 1.5-15 K exhibits spin-reorientation and Schottky anomalies. The magnetic field dependence of the reorientation anomalies is consistent with phenomenological descriptions which predict that two second-order phase transitions occur in the reorientation process. These transitions are quite different from typical first-order or $\lambda$-type phase transitions. The Schottky anomalies give values for the exchange splitting of the ground state of the ${\mathrm{Yb}}^{3+}$ ions.

Recent Princeton-Pennsylvania $n-p$ differential cross sections are combined with existing $n-p$ data at 210 and 330 MeV in order to obtain partial-wave representations of the $T=0\mathrm{}$ $N-N$ scattering matrix. The new data differ significantly from the existing large-angle cross sections at these energies, being more sharply peaked at the back angle and differing by as much as 30% in the midrange (near 90°). We find the new data inconsistent through phase-shift analyses with the older data, particularly at 330 MeV, even with a variety of renormalization methods. If the older data are eliminated, we find that the resultant solutions differ greatly from the expected one-pion exchange contribution values at 330 MeV, the best of these solutions requiring ${g_{\pi }}^2={18.9}_{\pm }1.2$.

The energy dependence and surface geometry of an optical-model equation with a non-local potential are compared with corresponding properties of optical-model equations with local and velocity-dependent potentials which are used to generate approximate solutions to the nonlocal-potential equation.

Transitions to known single-particle states in ${}_{}{}^{91,93,95,97}{}_{}{}^{}\mathrm{Nb}$ are observed in the (${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$) reaction induced by the bombardment of ${}_{}{}^{90,92,94,96}{}_{}{}^{}\mathrm{Zr}$ with 60 MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ions. Other strong transitions are also observed in this reaction, however, and evidence is presented which suggests that the final states observed are proton plus core vibrational states. The (${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$) reaction is found to populate many states in ${}_{}{}^{92,94}{}_{}{}^{}\mathrm{Mo}$ and possibly ${}_{}{}^{96}{}_{}{}^{}\mathrm{Mo}$, but few in ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$. The number and intensity of the states observed show a marked dependence on the neutron number of the target nucleus. The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ energy spectra for all the targets indicate that for the nuclei and incident energies used in the present experiments the main mechanism of the (${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$) reaction is breakup of the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ projectile.

Angular correlation measurements involving the reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},\alpha ){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}_{}^{*}{}_{}{}^{}\to \alpha +{}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}_{}^{*}{}_{}{}^{}$, leaving ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ in its first excited state, have been used to study several highly excited states in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$. The method was tested using the known $8^{+}$ state at 14.14 MeV. The results indicate that the triplet of states at 16.30, 16.55, and 16.84 MeV all have high spin (probably 8, 9, or 10). In the analysis it was assumed that the decay proceeds by the lowest allowed $L$ value.

A new model is described for the interaction between a moving charged particle executing any two-dimensional motion and an infinite, homogeneous, linear dielectric. The model is based on the exact solution of the self-consistent integro-differential equation of molecular optics. The main results are illustrated by application to the Cherenkov effect.

We present data on the reaction $K^{+}p\to K^{+}p$ at large angles. Between the forward diffraction peak and the backward peak the cross section is independent of four-momentum transfer but varies with incident momentum.

Experimental data are presented for the forward scattering of $K^{+}$ from the reaction ${\pi }^{-}p\to K^{+}\Sigma {\mathrm{}\left(1385\right)\mathrm{}}^{-}$. This "forbidden" peripheral scattering can not be explained by any simple kinematic effects in the $\Lambda K^{+}{\pi }^{-}$ final state. $s$-channel resonances, two-particle exchange, or a single "exotic"-meson exchange in the $t$ channel are examined as possible explanations of this effect.

The longitudinal momentum distribution of ${\pi }^{-}$ meson from the reaction $K^{+}+p\to {\pi }^{-}+$ anything at 11.8 $\frac{\mathrm{GeV}}{c}$ is examined in various reference frames. A forward-backward symmetry is found in that frame corresponding to a simple quark model. The frame of symmetry is dependent on the charged-particle multiplicity, however, which reduces the appeal of that model in explaining the present data.

On the basis of the Harari-Freund hypothesis that the background in the two-body reactions can be identified with the Pomeranchuk contribution, we point out that an analysis of the background in the resonance region of inclusive reactions gives the triple Reggeon couplings involving the Pomeranchukon. This is feasible at presently available energy. Combining this with the hypothesis that the triple Pomeranchukon coupling is extremely small, we arrive at the conclusion that the background cannot be produced diffractively. This can be used to define resonances such as $A_1$.

The impact of 5-MeV nitrogen ions on aluminum produces A1 $K\alpha$ and $K\beta$ x-ray satellites not previously observed with other means of excitation. Comparison of measured and calculated x-ray energies shows that the satellites arise from A1 ions with up to five $L$-shell vacancies.

The components of the fluorine chemical-shift tensor in Mg${\mathrm{F}}_2$ have been measured using the recently developed multiple-pulse NMR techniques. Relative to HF the three principal values of the chemical-shift tensor are - 26, - 11, and +4 ppm.

It is argued that except in special cases the diameter of the liquid-vapor coexistence curve should have a temperature derivative at least as singular as the constant-volume specific heat. No assumptions are made about the equation of state near the critical point other than the hypothesis of Griffiths and Wheeler that the only direction in the $\mu -T$ plane "singled out by the nature of the phase transition itself is a direction parallel to the coexistence curve."

A toroidal plasma heated by an energetic neutral beam (thus consisting of an energetic ion component and a lower-energy bulk plasma) can produce net thermonuclear power under conditions far less restrictive than Lawson's criterion.

We have demonstrated efficient guidance and transport of high-$\frac{\nu }{\gamma }$ electron beams along a $z$ pinch. Pinch currents substantially smaller than the beam current are sufficient to contain and propagate the beam. The data suggest single-particle motion of beam electrons in the pinch magnetic field. Numerical calculations of possible trajectories correlate with observed beam expansion and corroborate the single-particle analysis.