The question of localization is examined by employing the localization function method in the limit of infinitesimal disorder for a square-lattice tight-binding model. Within numerical accuracy we find that the localization function equals to 1 within the band; this strongly indicates that all eigenstates become localized for nonzero disorder.

The transconductance of an accumulation layer on $n$-type InAs is studied in a magnetic field $\overrightarrow{\mathrm{H}}$ parallel to the layer. Structures are observed, nonperiodic in $\frac{1}{H}$, corresponding to mixed electric and magnetic subbands. The effect promises a simple, sensitive method of probing the shape of the self-consistent potential in surface space-charge layers with multiply occupied subbands.

It is observed that the line shapes of core levels in photoelectron spectroscopy of Ti, Th, and Ce and some of their intermetallic compounds and lanthanide oxides are directly related to the degree of localization of screening orbitals.

Gold was deposited on Pt(100) and platinum was deposited on Au(100) single-crystal surfaces. Cyclohexene dehydrogenation rates were enhanced about fivefold relative to clean Pt(100) by just one monolayer of gold on Pt(100) and also by ordered platinum layers on inactive Au(100).

From a sample of 20 072 dimuon final states, a first determination of the structure function $F_2\left(c\overline{c}\right)$ for diffractive charmed-quark pair production by 209-GeV muons is obtained. $F_2\left(c\overline{c}\right)$ has a $\nu$ dependence similar to that of the photon-gluon fusion model, but its $Q^2$ dependence peaks at lower $Q^2$. Diffractive charm production accounts for $\sim \frac{1}{3}$ of the scale noninvariance observed in muon-nucleon scattering at low values of the Bjorken $x$ variable, $x_{\mathrm{B}}$.

The $\pi \pi \to \overline{K}K$ $S$ wave has been extracted from an amplitude analysis of $\overline{K}K$ production. With use of unitarity constraints, evidence has been found for a resonance in $\pi \pi \to \overline{K}K$ at 1425±15 ${\mathrm{M}\mathrm{e}\mathrm{V}/\mathit{c}}^2$ having a width 160±30 ${\mathrm{M}\mathrm{e}\mathrm{V}/\mathit{c}}^2$; this state is a likely candidate for the $Q\overline{Q}$, $J^{\mathrm{PC}}=0^{++}$ nonet. It is shown that the $S^{*}\mathrm{}\left(980\right)\mathrm{}$, which is a background to this resonance, must be a very broad effect and is likely a $\overline{K}K$ virtual bound state.

Excitation functions for complete fusion of ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ + ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ + ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ + ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ have been determined over a range of energies from just above to well below the fusion barrier. The response of these excitation functions to the addition of valence neutrons is found to be surprisingly complex. We suggest that at least part of the observed variations may be due to dynamic, single-particle effects.

The $\gamma$-decay and nuclear structure of low-lying yrast and near yrast levels in ${}_{}{}^{210}{}_{}{}^{}\mathrm{Rn}$ and ${}_{}{}^{211}{}_{}{}^{}\mathrm{Rn}$ have been investigated. The cascade from the yrast $6^{+}$ state in ${}_{}{}^{210}{}_{}{}^{}\mathrm{Rn}$ branches to two close-lying $4^{+}$ states, deduced to be complete mixtures of the $4^{+}$ states arising from the proton configuration, and from the neutron-hole intruder configuration. The influence of this proton-neutron-hole interaction on the yrast cascades in ${}_{}{}^{211}{}_{}{}^{}\mathrm{Rn}$ and ${}_{}{}^{206}{}_{}{}^{}\mathrm{Rn}$, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Rn}$ is discussed.

The systems ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been studied in the inelastic channel leaving ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ in the 6.05-MeV excited $0^{+}$ state. This channel has a grazing angular momentum ∼2.5 units less than the elastic channel. Surprisingly, the excitation functions show pronounced peaks which are closely correlated with the well-matched ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$($3^{-}$, 6.13 MeV) channel. This correlation demonstrates the importance of the wave reflected from the interior of the ion-ion potential.

The first measurement of the hfs interval $\Delta \nu$ for the muonic helium atom ${\left({}_{}{}^4{}_{}{}^{}\mathrm{He}_{}^{++}{}_{}{}^{}{\mu }^{-}{e}^{-}\right)}^0$ is reported. In terms of its electronic structure, it is a heavy isotope of hydrogen. Polarized atoms are formed by stopping polarized negative muons in a helium-gas target at 19.4 atm with a 1.5% admixture of Xe. The ground-state hfs splitting $\Delta \nu$ was measured through observation of a microwave magnetic-resonance transition at zero magnetic field. After correction for the hfs pressure shift, we determine $\Delta \nu =4464.95\mathrm{}\left(6\right)\mathrm{}$ MHz (13 ppm).

The distribution of first-passage times is calculated for a homogeneously broadened two-mode laser, that is characterized by a bistable potential. As a consequence of quantum fluctuations, such a system tends to switch spontaneously between the two metastable states. The results of the calculation are compared with first-passage-time measurements of a two-mode dye laser.

Asymptotic approximations to the Mie efficiency factors for extinction, absorption, and radiation pressure, derived from complex-angular-momentum theory and averaged over $\Delta \beta \sim \pi$ ($\beta =\mathrm{size}\mathrm{parameter}$), are given and compared with the exact results. For complex refractive indices $N=n+ik$ with $1.1<~n<~2.5$ and $0<~k<~1$, the relative errors decrease from ∼(1-10)% to ∼(${10}^{-2\mathrm{}}$-${10}^{-3\mathrm{}}$)% between $\beta =10\mathrm{}$ and $\beta =1000\mathrm{}$, and computing time is reduced by a factor of order $\beta$, so that the Mie formulae can advantageously be replaced by the asymptotic ones in most applications.

C${\mathrm{O}}_2$-laser-driven implosions have been shown to produce compressed plasma densities of the same magnitude as ordinary solids (>2 g/${\mathrm{cm}}^3$). A variety of diagnostic techniques has been used, including the simultaneous observation of x-ray spectroscopic signatures and nuclear yield. The laser energy on target ranged from 3 to 6 kJ and the half width of the pulse was 600-800 ps. The results of these experiments are compared with numerical hydrodynamic simulations.

A potential double layer is observed when an ion beam is injected into a collisionless magnetoplasma along converging magnetic field lines and reflected at a positive electron-absorbing boundary. The double layer is $V$ shaped, highly stationary, strong ($\frac{e\varphi }{k{T}_e}\lesssim 25$) with amplitude determined by the beam energy ($\varphi \lesssim V_b$), and occurs with magnetized (${\mathrm{H}}_2^{+}$) and unmagnetized (${\mathrm{Ar}}^{+}$) ions. Distribution function measurements show self-consistently formed trapped electrons on the high-potential side.

It is shown how the molecular weight dependence of the radius of gyration $R_{F2\mathrm{}}$ of two-dimensional polymeric chains can be derived from surface-pressure isotherms in Langmuir monolayers. $R_{F2\mathrm{}}$ scales as $N^{\nu }$ with $\nu =0.56\mathrm{}$ for polymethylmethacrylate and 0.79 for polyvinylacetate. These values are in agreement with the scaling predictions for tricritical and excluded-volume behaviors, respectively. The crossover between the dilute and the intermediate regimes is also clearly observed in one case.

Numerical transfer-integral and molecular-dynamics calculations are used to demonstrate that the mapping of an easy-plane ferromagnet in a field to the sine-Gordon system fails. The crucial implication for CsNi${\mathrm{F}}_3$ is that the central peak observed by Kjems and Steiner at $T=10\mathrm{}$ K is more likely to be due to multimagnon difference processes, or pulse-soliton features of the nearly isotropic model rather than due to kink or breather solitons.

Two ESR modes in CuMnNi spin-glass alloys are observed. Both modes are interpreted with a phenomenological theory incorporating an order parameter, remanent magnetization, and anisotropy energy. From simultaneous magnetization and ESR measurements, it has been possible to deduce the temperature and concentration dependence of the anisotropy constant, which has interesting scaling properties. The angular dependence of the field-cooled ESR and magnetization data suggest the need for another order parameter which vanishes at $T_g$.

Paramagnetic resonance experiments at 3 and 9 GHz were performed in dilute $Au:\mathrm{Yb}$ in the temperature range from 100 mK to 4 K. All results show for the first time a logarithmic temperature dependence for the $g$-value shift and for the relaxation rate in complete agreement with theoretical predictions. The fit yields a Kondo temperatue of $T_{\mathrm{K}}\sim 10$ μK and a degeneracy of $d\sim 3$ for the local-moment-conduction-electron interaction channels.

Intrinsic collective losses are observed in the core-level spectra of Ca, Sr, and Ba that exceed those observed in Al, Mg, and Na by factors up to 10. The coupling strength depends on the nature of the core hole. The relationship between the strength of the collective excitations and the extraatomic relaxation energies explains increases of 1.0 eV and 0.3 eV in Ca $3p$ and Sr $3p$ splittings compared to the free-ion spin-orbit splittings.

This Letter reports the first ultrahigh-vacuum study of surface-enhanced Raman scattering from pyridine adsorbed on a clean single-crystal silver surface containing a smooth modulation (1 μm periodicity) to allow optical coupling to surface plasmon polaritons. A large mode-selective enhancement (∼${10}^4$) of the Raman signal from the first monolayer is observed at surface-plasmon-polariton resonance. Coverages greater than one monolayer show a smaller enhancement (∼${10}^2$).