I derive the new relation ${{\Lambda }_{-}}^0:{{\Sigma }_0}^{+}:{{\Xi }_{-}}^{-}=1:-\sqrt{3}:-2\mathrm{}$ for the $S$-wave amplitudes of the hyperon nonleptonic decays, assuming SU(4) 20-plet dominance for the weak interaction of current-current type. I also discuss the nonleptonic decays of charmed mesons.

We have observed short-duration birefringence in C${\mathrm{S}}_2$ vapor 38 and 76 psec after excitation with a mode-locked (∼ 5 psec duration) 1.06-μm glass: ${\mathrm{Nd}}^{3+}$ laser pulse. These bursts are attributed to the time evolution of a coherent sum of rotational superposition states.

The electronic quadrupole moments of ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}_2$ are quadratic in the internuclear distance $R$ at short distances and the coefficient of proportionality is the quadrupole shielding factor of the ${\mathrm{He}}^{+}$ or He atom, respectively. The behavior of the quadrupole moment of ${\mathrm{H}}_2^{+}$ at short and long distances can be used to approximate it at all distances.

We report the first experimental observation of broad-banded re-emission resulting from quasi-elastic collisional transfer processes. The data may be interpreted by the general theory of scattering of monochromatic light in gases. The connection between this theory and one derived for solids is discussed.

The $K$ fluorescence yields ${\overline{\omega }}^i$ of Ne ions with 0-6 $L$-shell vacancies (charge states $K{L}^i$) have been calculated by computing term transition rates for initial multiplet states and statistically averaging individual multiplet fluorescence yields. We find ${\overline{\omega }}^i=0.0159, 0.0176, 0.0199, 0.0248, 0.0390, 0.0862, \mathrm{and} 0.229$ for $i=0, \dots , 6$. Existing measurements are critically reviewed and found to agree with present theoretical results once proper account is taken of the ${}_{}{}^4{}_{}{}^{}P\left(K{L}^6\right)$ intensity contained in the $K{L}^5$ x-ray peak.

Absolute x-ray emission spectra in the range from 1 to 300 keV were measured from C${\mathrm{H}}_2$ plasmas produced at the focus of a high-power (> ${10}^{16}$W/${\mathrm{cm}}^2$) 1.06-μm laser. Experimental spectra are compared with hydrodynamic-model predictions. The good agreement indicates that suprathermal electrons are unimportant in the interaction and that self-generated magnetic fields dominate the thermal transport.

It is shown that the internal kink mode is no longer marginally stable within the kinkmode order in a plasma with noncircular cross section. For a step current density with a small ellipticity, the internal kink mode becomes unstable as soon as the rotational transform exceeds $2\pi$ close to the magnetic axis.

The law of conservation of charge is used to express the x-ray photoemission spectroscopy (XPS) line shape of a metal in terms of its observed threshold exponents, ${\alpha }_0$ and ${\alpha }_1$, within the framework of the many-electron theories of Doniach, Sunjic, Mahan, Nozières, and de Dominicis. The many-body theory predicts an anomalous dependence of XPS asymmetry on conduction-electron density: With increasing density, the XPS line should become more symmetric.

The optical absorptivities of oriented single crystals of hcp Gd, Tb, Dy, Ho, Er, Tm, and Lu were measured at 4.2 K between 0.2 and 4.4 eV. Polarized radiation was used to reveal the optical anisotropy. Systematic movement of structures in the absorptivity and optical conductivity was observed as a result of trends within $\mathrm{sp}$ and $d$ bands. Low-energy structures were related to effects of $s-f$ exchange interaction, but were more complicated than previously thought.

We demonstrate, via low-temperature optical-absorption measurements on ultrathin, coupled potential wells in molecular-beam-grown ${\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$-GaAs heterostructures, the evolution of resonantly split discrete well states into the lowest band of a one-dimensional superlattice. Both electron and hole superlattices appear to be practical.

Plasmons in the one-dimensional organic metal tetrathiafulvalene-tetracyanoquinodimethane were directly measured by high-energy inelastic electron scattering in thin crystalline films at 300°K. For plasmons propagating along the conducting $b$ axis the plasmon energy decreases from 0.75 to 0.55 eV and the width increases linearly as the plasmon momentum increases. Plasmons at 45° to $b$ have an energy of 0.6 eV and show no dispersion.

Elementary considerations permit the pressure derivatives of the compressibility and of the dielectric constant to be related to more easily measurable quantities. Quantum mechanics, for example, the theory of the hydrogen-molecule ion, shows that the bonding and antibonding states of a covalent bond are simply related. Thus, optical energy gaps and compressibilities can be combined to define the energetics of the bonds. Values of pressure derivatives thereby predicted compared favorably with experiment.

Intrinsic surface electronic energy states for the ideal (1 × 1), relaxed (1 × 1), and reconstructed (2 × 1) Si(111) surfaces have been successfully calculated by use of the self-consistent scattered-wave cluster model. For both ideal and relaxed structures, we find three bands of surface states. For (2 × 1) reconstruction our dangling-bond surface band splits into two overlapping bands. Our results account for all the observed features in photoemission experiments on Si(111) surfaces.

Neutron-sputtering ratios are reported for ($d, t$) neutrons incident upon Nb and Au foils. The measured ratios are lower than most previous results. For annealed Au as well as for cold-worked Nb the best values for the sputtering ratios are in the range $S_n\lesssim \mathrm{}(1.2-2.5)\mathrm{}\times {10}^{-5\mathrm{}}$. These results are in good agreement with theoretical predictions. A careful search for neutron-induced micron-sized particles yielded negative results.

An empirical linear-combination-of-atomic-orbitals energy-band model is described for simple-cubic and fcc TlCl, TlBr, and TlI which explains optical data and reproduces existent a priori band structures. This band model is used to discuss the type of bonding in the polymorphs, and to check the applicability for ten-electron systems of the Phillips-van Vechten dielectric theory of bonding.

Optically induced ESR and absorption due to localized paramagnetic states in the forbidden gap have been observed in several semiconducting chalcogenide glasses below ∼15 K. Analysis of the ESR spectra indicates that these centers are holes localized on chalcogens and are not directly associated with impurities.

Results of the reaction ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}({}_{}{}^7{}_{}{}^{}\mathrm{Li}, p){}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ identify several levels below 5 MeV as candidates for high-spin states predicted by shell-model calculations, but heretofore undiscovered. The 2.97-MeV level is found to be a doublet.

We note the following: The quark model implies that superdense matter (found in neutron-star cores, exploding black holes, and the early big-bang universe) consists of quarks rather than of hadrons. Bjorken scaling implies that the quarks interact weakly. An asymptotically free gauge theory allows realistic calculations taking full account of strong interactions.

We present cross sections for $e^{+}{e}^{-}\to \mathrm{hadrons}$, $e^{+}{e}^{-}$, and ${\mu }^{+}{\mu }^{-}$ near 3095 MeV. The $\psi \mathrm{}\left(3095\right)\mathrm{}$ resonance is established as having an assignment $J^{\mathrm{PC}}=1^{--}$. The mass is 3095 ±4 MeV. The partial width to electrons is ${\Gamma }_e=4.8\mathrm{}\pm 0.6$ keV and the total width $\Gamma =69\mathrm{}\pm 15$ keV. Total rates and interference measurements for the lepton channels are in accord with $\mu -e$ universality.

Cross sections for the process ${\mathrm{H}}^{+}$ + H → ${\mathrm{H}}^{+}$ + H* ($n=2\mathrm{}$) are determined from the energy-loss spectra of 15-200-keV protons. After normalization at 200 keV to the Born approximation, the maximum value (1.07 × ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$ at 60 keV) lies below close-coupling calculations and above Glauber-approximation calculations. The agreement with low-energy (5-30-keV) data of others is very good.