A one-dimensional analog of the Kondo lattice is studied by a renormalization-group technique. Previous mean-field results are shown to be reasonable: The system under-goes a second-order crossover transition from an antiferromagnetic state to a Kondo-like state at zero temperature as the spin-conduction-electron coupling is increased. Estimates are given for critical exponents and the behavior of correlation functions near the transition.

The condition of self-duality for a SU(2) gauge field on Euclidean four-dimensional flat space is integrated once to obtain Laplace-like equations for three real variables or for variables one real and one complex. A special case of the latter reduces to the Corrigan-Fairlie-Wilczek-'t Hooft Ansatz.

Five new, neutron-rich nuclides, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{31}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{34}{}_{}{}^{}\mathrm{Al}$, and ${}_{}{}^{39}{}_{}{}^{}\mathrm{P}$, have been produced by the bombardment of uranium with 800-MeV protons. A time-of-flight method which utilizes the rf structure of the beam was combined with a $\Delta E-E$ measurement to identify the nuclides.

According to present theories of the dipersion relation for a $\pi$ meson within nuclear matter, decays such as $\gamma \to {\pi }^{+}+{\pi }^{-}$ and $\overline{\nu }\to e^{+}+{\pi }^{-}$ are allowed within nuclei. Observation of nuclear processes instigated by these decays can provide information on the pion dispersion relations and on weak and electromagnetic form factors in nuclear matter.

High-spin "particle-hole" states in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ [$E_x=14.350\mathrm{}$ MeV, $(J^{\pi }, T)=(6^{-}, 1)$; $E_x=12.656\mathrm{}$ MeV, ($4^{-}$, 1); $E_x=11.580\mathrm{}$ MeV, ($6^{-}$, 0] and in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ [$E_x=15.137\mathrm{}$ MeV, ($6^{-}$, 1)] are observed to be strongly excited by inelastic scattering of 135-MeV protons at momentum transfers of 200-450 MeV/c. Use of a new energy-independent pseudopotential in plane-wave impulse approximation explicitly including exchange provides good agreement with the data.

The first optical absorption from excited states to autoionizing core-excited levels has been observed in lithium. A 1-MW dye laser tuned to the $1s^{2}2s\to 1s^{2}2p$ resonance produced ∼${10}^{16}$ excited atoms/${\mathrm{cm}}^2$ in a heat-pipe oven. Far-uv absorption spectra of ${\mathrm{Li}}^{*}\mathrm{}\left(2p\right)\mathrm{}$ and ${\mathrm{Li}}^{+}$ were obtained. A curve of the evolution from excited neutrals to ∼95% ions is presented, and the significance of the Li observations for understanding the ionization mechanism is discussed.

A diamagnetic shift in atomic hyperfine structure has been observed for the first time. The shift in the dipole hyperfine separation in ${}_{}{}^{85}{}_{}{}^{}\mathrm{Rb}$ has been measured by a high-field laser optical-pumping technique and found to be 1.65(16)×${10}^{-8\mathrm{}}$ Hz/${\mathrm{G}}^2$. In addition, the nuclear- to electronic—$g$-factor ratio, $\frac{g_I}{g_J}$, has been determined to be - 1.466490 93(11) × ${10}^{-4\mathrm{}}$, independent of magnetic field.

Polarization-dependent absorption of obliquely incident laser radiation by dense plasmas has been observed. Irradiation of a planar plasma with a nearly collimated $p$-polarized laser beam shows an enhancement in absorption by a factor of 2 to 2.5 over $s$-polarized irradiation. Theoretical estimates of the effect of resonance absorption under the present conditions show agreemwnt with the experimentally observed results.

Rapid heating of ions and electrons to keV temperatures in ≲ 1 μsec has been observed at densities of 1×${10}^{14}$ ${\mathrm{cm}}^{-3\mathrm{}}$. This is to be compared with experiments in which energy losses along the magnetic field limit the electron temperature. The most striking difference is in the ratio of electron to ion temperature which is now ≲ 0.3 as in comparable open-ended $\theta$ pinches.

The steady-state electron distribution function of a current-carrying magnetized plasma is determined self-consistenly with the enhanced $\omega =\frac{{\omega }_{\mathrm{pe}}{k}_{\parallel }}{k}$ plasma wave spectrum it generates. Consequences include enhanced fluctuations at $\omega \simeq {\omega }_{\mathrm{pe}}$ and energy transport by $\omega <{\omega }_{\mathrm{pe}}$ waves which is found to be greater than that by neoclassical ion thermal conduction and of the order of the observed transport in intermediate-density tokamaks.

A model for the atomic structure of the Si(111) 7×7 surface is presented on the basis of recent experimental low-energy electron diffraction (LEED) studies. The seventhorder diffracted beams are attributed to interference in the coherent scattering from the first two lattice double layers which are considered rippled with a space periodicity of seven unit cells of the ideally terminated lattice. This distortion is caused by compressive stress in the surface plane that stems from the trend toward $s{p}^2$ hybridization in these two double layers due to the presence of the free surface.

A relatively large population of bulk dipoles can be detected in amorphous selenium, a homopolar solid, via the coupling they provide between an applied ac electric field and the large-scale cooperative molecular motion thermally excited at the glass transition temperature. Although the structural-chemical origin of the contributing dipoles is not determined, their presence provides a unique opportunity to study a primary molecular relaxation process in an important class of amorphous semiconductors.

It is shown that the Raman line-shape function and/or vibrational dephasing times can reflect random frequency modulation of high-frequency vibrational modes via exchange with low-frequency modes. When exchange is incorporated into the vibrational correlation function, lifetimes and scattering rates between modes can be quantitatively determined from the temperature dependence of the spontaneous Raman spectrum. Finally, some experimental results on vibrational redistribution are presented which demonstrate the salient features of the theory.

Synchrotron radiation ($h\nu =80-170\mathrm{}$ eV) was used for photoemission studies of CO chemisorption on a Pt crystal. We report the first unambiguous observation of the $3\sigma$ molecular level for CO adsorbed on a metal surface and note a relaxation shift 2.4 eV larger for the $3\sigma$ than for the $4\sigma$ as compared to the $3\sigma -4\mathrm{}\sigma$ splitting in the gas phase. Furthermore, we observe energy-loss structure between the $3\sigma$ and $4\sigma$ levels, reminiscent of the shakeup satellites in transition-metal carbonyls.

A new method of determining the lateral structure of crystal surfaces is described. The dispersion of electronic surface resonances at energies of the order of 10 eV above the vacuum level is measured, and the results are interpreted using a nearly free-electron method to determine low-index Fourier coefficients of the potential acting on electrons near the surface. The method is shown to reproduce the known lateral structure of $\mathrm{Ni}\mathrm{}\left(001\right)c(2\mathrm{}\times 2)\mathrm{O}$ surface.

It is shown that a flux vortex, in the presence of a sufficiently large current density applied parallel to its axis, is unstable against the growth of helical perturbations. This instability, which has an analog in magnetohydrodynamics, may play a critical role in current-carrying type-II superconductors subjected to longitudinal magnetic fields.

I present a theory of the electron energy-loss spectra observed in x-ray photoemission from the core levels of solids and report on calculations for the $2s$ and $2p$ core levels of Al, Mg, and Na. The calculation takes intrinsic as well as extrinsic plasmons into account, and in all cases the agreement between theory and experiment is very good.

In Wilson's lattice gauge theory, we obtain an effective Lagrangian for a string with quarks attached to the ends. A set of classical solutions are obtained, and quantized by the Bohr-Sommerfeld method to give the Regge trajectories. The ground-state spectra are those of the SU(6) model in the classical limit.

We have observed the decay ${D^{*}}^{+}\to D^0{\pi }^{+}$ and have measured its $Q$ value to be 5.7±0.5 MeV. The decay width of the ${D^{*}}^{+}$ is less than 2.0 MeV/${\mathit{c}}^2$. The observation of ${D^{*}}^{+}\to \left(K^{-}{\pi }^{+}\right){\pi }^{+}$ but not of ${D^{*}}^{+}\to \left(K^{+}{\pi }^{-}\right){\pi }^{+}$ sets an upper limit on the amount of $D^0-{\overline{D}}^0$ mixing.

Neutron-proton differential cross sections have been measured with good statistics for four-momentum transfers $0.14<-t\lesssim 19.0$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ at laboratory momenta ranging from 4.5 to 12.5 GeV/c. The experiment was carried out in a neutron beam at the Argonne National Laboratory zero-gradient synchrotron. These results in conjunction with previous $n-p$ charge-exchange data provide almost complete elastic-scattering angular distributions in this momentum range.