Resonant Raman scattering in Mn${\mathrm{F}}_2$ around the magnon sidebands selects a particular set of two-magnon modes to be resonantly enhanced. Consequently, the two-magnon line shifts with the laser frequency and two two-magnon lines can show up simultaneously. A simple theory is used to interpret the experimental results.

This paper reports the lattice constant at room temperature and the susceptibility, specific heat, electrical resistivity, and absolute Seebeck coefficient of compounds $\mathrm{U}{\mathrm{Ni}}_{5-x}{\mathrm{Cu}}_x$ ($0\le x\le 5$) as a function of temperature. It is suggested that the drastic change in the properties of these compounds when $x$, increasing from 0, comes into the range of 4 to 5 is caused by a change of the uranium ions from a ${\mathrm{U}}^{4+}$ to a mixed ${\mathrm{U}}^{4+}$-${\mathrm{U}}^{3+}$ state.

A simple criterion for the renormalizability of paramagnon theories is presented. In contrast to other well-known problems, the paramagnon theory is shown to be renormalizable for the case of a nearly ferromagnetic, three-dimensional fermion system at $T\cong 0$ K.

Polarized ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ nuclei ($T_{\frac{1}{2}}=0.84\mathrm{}$ sec), produced in ${}_{}{}^7{}_{}{}^{}\mathrm{Li}(d, p){}_{}{}^8{}_{}{}^{}\mathrm{Li}$ with polarized deuterons, were implanted in a thick LiI${\mathrm{O}}_3$ crystal used as the target. The asymmetry in the $\beta$ decay of ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ was used to detect NMR in a strong magnetic field. About $\frac{1}{3}$ of the ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ nuclei found Li substitutional sites where the polarization persisted for $T_1\approx 11$ sec. The quadrupole moment of ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ was determined from a knowledge of the electric field gradient in LiI${\mathrm{O}}_3$.

Two direct search methods have been applied to extract the optimum optical-model parameters for the elastic scattering of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ by ${}_{}{}^{12,13,14}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ by ${}_{}{}^{13,14}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ by ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ for center-of-mass energies in the range 7.8 to 12.6 MeV. The success of the analysis suggests that it is possible to interpret these data in terms of an optical-model potential alone, indicating that such experiments do not provide unambiguous evidence for interference between the elastic-scattering and elastic-transfer modes.

We have used a neutron interferometer to observe the quantum-mechanical phase shift of neutrons caused by their interaction with Earth's gravitational field.

We have measured inclusive cross sections for the reaction $\mathrm{pd}\to \mathrm{pX}$ in the region $0.15<\mathrm{}\left|t\right|<0.39\mathrm{}$ Ge${\mathrm{V}}^2$, $100<s<\mathrm{}750\mathrm{}$ Ge${\mathrm{V}}^2$ and $0.80<x<\mathrm{}0.92\mathrm{}$ using the acceleration ramp and deuterium-gas jet target at Fermilab. These measurements are combined with our earlier measurements of $\mathrm{pp}\to \mathrm{pX}$ to obtain inclusive cross sections for $\mathrm{pn}\to \mathrm{pX}$.

The $K$-edge photoabsorption spectra of Kr, Br in ${\mathrm{Br}}_2$, and Ge in Ge${\mathrm{Cl}}_4$ were measured using synchrotron radiation from SPEAR, Stanford's $e^{+}{e}^{-}$ storage ring, which provides a factor of 5×${10}^4$ improvement in intensity over a conventional x-ray source. The agreement between theory and experiment is only qualitative.

The decay rates of the vibrational levels $v=3\mathrm{}$ to $v=13\mathrm{}$ in ground-state ${\mathrm{N}}_2$ have been measured in solid nitrogen between 4.2 and 18 K. In N-atom-doped but otherwise highly purified solid ${\mathrm{N}}_2$, the vibrational relaxation rates are found to be fitted by the expression $P_{v\to v-1\mathrm{}}=A_v+B_v\exp (-\frac{\Delta E_v}{\mathrm{kT}})$. The rate $A_v\cong v\times \left(1\mathrm{} invsec\right)$ is interpreted as the multiphonon creation rate in the $v\to v-1\mathrm{}$ relaxation, while $B_v\cong 6\times {10}^8$ ${\sec }^{-1\mathrm{}}$ near $v=10\mathrm{}$ describes the intermolecular transfer of a vibrational quantum, ${\mathrm{N}}_2\mathrm{}\left(v\right)+{\mathrm{N}}_2\mathrm{}\left(0\right)\mathrm{}\to {\mathrm{N}}_2\mathrm{}(v-1\mathrm{})+{\mathrm{N}}_2\mathrm{}\left(1\right)\mathrm{}$, with energy mismatch $\Delta E_v=E_1-E_0-E_v+E_{v-1\mathrm{}}$.

The separated-oscillatory-field technique has been used with a fast atomic beam to measure in zero magnetic field the $2{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}\to 2{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ Lamb-shift interval in hydrogen. Resonance lines narrower than the natural linewidth by a factor of 3 were used to obtain $S(H, n=2)=1057.893\mathrm{}\left(20\right)\mathrm{}$ MHz. This result has a factor of 3 increase in precision over earlier measurements.

Near the critical point of a fluid or fluid mixture, we postulate the existence of a size distribution of diffuse droplets or clusters of molecules. This distribution is combined with the Rayleigh-Debye scattering approximation and the theory of Brownian motion to describe the observed behavior of the intensity and the autocorrelation of light scattered by critical fluids.

Using a novel diagrammatic perturbation-theory approach, it is found that the dynamic structure function of quantum fluids at high frequencies is independent of quantum statistics, depends only on the interparticle potential, and has a long tail as a function of frequency. In particular, it is found that the fifth and higher frequency moments diverge in charged quantum systems. This is demonstrated to hold in general by an investigation of the fifth-moment sum rule.

A theory of the sound attenuation and dispersion in superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is presented, which consistently takes into account three types of absorption mechanisms: (1) quasiparticle collisions, (2) pair breaking, and (3) excitation of collective modes of the order parameter. Results for the $B$ phase, assuming it to be in the quasi-isotropic (Balian-Werthamer) state, are in good agreement with experiment.

A systematic kinetic-theory treatment of the interaction of electrons and ions with intense high-frequency localized electrostatic fields is formulated. A generalization of the familiar nonlinear Schrödinger equation includes nonlinear Landau-damping effects which prevent soliton collapse. An analytic calculation predicts a heated-electron distribution behaving asymptotically as $\exp (-\frac{v}{v_0})$ ($v_0=\frac{e{\mathcal{E}}_0}{4m{\omega }_0}$) and modulated in the region near the localized field to form streamers in phase space.

A recently developed method for the self-consistent calculation of localized configurations has been applied to the Si(111) surface. Results have been obtained for unrelaxed, relaxed, and (2×1) reconstructed (buckled) surfaces. Densities of states and charge densities are presented and discussed. The salient experimental findings are reproduced.

Using x-ray diffuse scattering, we have observed enhanced Kohn anomalies in the two-dimensional conductor ${\mathrm{Ta}}_{0.9}$${\mathrm{Hf}}_{0.1}$${\mathrm{S}}_2$. From this, we have deduced the shape of the Fermi surface of this compound throughout a wide region of reciprocal space. The results in the ($h0l$) planes demonstrate the two-dimensionality of the electronic states in this substance. The results in the layers $h$, $k$, $\pm \frac{1}{3}$ prove that the topographic shape originally postulated by Williams, Parry, and Scruby is correct.

Giant quantum oscillations in the attenuation of Rayleigh waves with the magnetic field normal to the metal surface are reported. These oscillations have a spikelike character. The experiments are made at frequencies up to 120 MHz and temperatures down to 0.4 K. The line shape is studied and compared with that of the giant quantum oscillations in the attenuation of accoustic bulk waves in longitudinal magnetic field.

Relativistic Hartree-Fock-Wigner-Seitz band calculations have been performed for the actinide metals Ac through Am in order to estimate $5f$ excitation energies. Our calculations predict that the tetravalent state (i.e., four $s-d$ conduction electrons) is favored for the lighter elements with a crossover to a trivalent ground state occurring near uranium. We find the Coulomb energy, $U$, for $5f$ electron hopping to increase from 2-3 eV at Th to 4-5 eV at Am.

It is shown on the basis of isospin arguments that the deformation parameter ${\beta }_2$ for $2^{+}$ first excited states is expected to be a function of the external field producing the transition. This is contrary to the usual assumption based on the collective model that $\beta$ is an intrinsic property of the nucleus and is, therefore, the same for all kinds of transitions. Data available in the literature support the expectation.

Bombarding Ni targets with 96-MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ions, we have observed deep-inelastic groups of mass-16 and -12 reaction products with $Q$ values centered at -30 to - 35 MeV. From the multiplicity of the coincident $\gamma$ de-excitation, total fragment spins and hence, using a classical model, orbital angular momentum transfers of $12\hslash$ to $15\hslash$ are deduced. These, and at least 50% of the energy dissipation, are ascribed to tangential friction.