Angle-resolved photoemission spectra obtained from the W{001}-(1 × 1) structure are compared with spectra from the cooled $(\sqrt{2}\times \sqrt{2})R45$° surface structure, providing the first experimental evidence for the coupling of surface states at the Fermi energy on formation of the latter phase. Calculations of the surface density of states are in good agreement with experiment. A prominent new feature observed from the low-temperature phase (at the 1 × 1 $\overline{M}$ point) is attributable to an umklapp process.

Surface-enhanced Raman signals are reported from pyridine adsorbed onto ${\mathrm{Ag}}_{1-x}{\mathrm{Pd}}_x$ for $x\lesssim 0.04$. For $x\gtrsim 0.05$ the alloys do not support enhancement within our limit of detection. The quenching is due to the introduction of Pd $d$ states which are involved in electron excitations that interfere with Ag's favorable free-electron-like behavior.

A theory of paired substitutional $s{p}^3$-bonded defects in zincblende hosts is presented and successfully applied to the (spectator, oxygen) paris (Zn, O) and ($V_{\mathrm{Ga}}$,O) in $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x$ and to (Mg, O), (Cd, O), (Zn, O), ($V_{\mathrm{Ga}}$,O), and (Si, O) in GaP. Spectator impurities, when paired with isolated oxygen, may alter the oxygen binding energy or even drive its deep $A_1$ level out of the band gap.

The large-angle analyzing power $A$ in proton-neutron elastic scattering at 2, 3, and 6 GeV/c with use of the polarized proton beam at the Argonne zero-gradient synchrotron and a liquid deuterium target have been measured. The measurements, the first at high energy, show that $A$ is large (20-40%) and negative over much of the angular range and shows no decrease with incident energy, unlike the earlier data at smaller angles.

In this Letter, a measurement of inclusive muon production ($p_{\mu }>2\mathrm{}$ GeV/c) in $e^{+}{e}^{-}$ annihilation into hadrons at center-of-mass energies from $\sqrt{s}=12\mathrm{} \mathrm{to} 31.6$ GeV is reported. The results agree with the expected semileptonic decays from charmed and bottom mesons.

This Letter incorporates confinement to the covariant parton model and investigates its consequences on the qualitative behavior of the deep-inelastic structure functions in the Bjorken limit. It is proved that this incorporation does not change the known behavior of the baryonic structure functions, but it leads, for mesons, to a nonvanishing value of $\nu W_2\left({\omega }^{-1\mathrm{}}\right)$ and $W_1\left({\omega }^{-1\mathrm{}}\right)$ in the ${\omega }^{-1\mathrm{}}\to 1$ limit and to a violation of the Callan-Gross relation.

In a theory where the fermion numbers $B$ and $L$ are not conserved, the true ground state is a condensate of fermion pairs and antifermion pairs. Because of this, the usual analysis of fermion oscillation based on complete analogy with $K-\overline{K}$ mixing must be revised.

Differential cross sections for ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$($\gamma$, ${\pi }^{+}$)${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ to the ground and first excited states of ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ separately and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$($\gamma$ ${\pi }^{+}$,)${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ to the sum of the four lowest-lying states in ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ have been measured at laboratory angles of 45° and 90° for pions with kinetic energies from 80 and 210 MeV. The results, which are the first to discrete nuclear final states in the $\Delta \mathrm{}\left(1236\right)\mathrm{}$ region, are in qualitative agreement with several distorted-wave impulse-approximation calculations.

The dependence of projectile double-$K$-vacancy (hypersatellite) x-ray yields on target thickness for ions moving in thin solid targets is examined. For 2.3-MeV/amu Cl ions incident on C foils, the double- to single-$K$-vacancy x-ray yield ratio increases by a factor of 3.5 over the range of thicknesses investigated, reaching values as high as 0.3. A quantitative explanation of the observed results is obtained using a formulation based on $K$-vacancy production and filling cross sections.

Total (elastic plus inelastic) differential scattering cross sections for 40-keV electrons incident on ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ have been measured with a precision of 0.1%. Theoretical scattering intensities as given by the independent-atom model are subtracted from the experimental results and compared with two theoretical predictions. The calculations of Liu and Bonham, which utilize a poor wave function and a rather crude vibrational averaging, agree qualitatively with our results. The disagreement may be explained by considering the vibrational dynamics of the charge cloud of the molecules.

Double-differential studies of the fast neutrals (Cl) resulting from collisional detachment of ${\mathrm{Cl}}^{-}$ on ${\mathrm{N}}_2$ ($E_{\mathrm{lab}}<~300$ eV) show energy-loss peaks at 6 and 12 eV. It is noteworthy that a high-loss peak is dominant at low $E\theta$. Similar studies of the inelastically scattered ${\mathrm{Cl}}^{-}$ reveal significant vibrational-rotational excitation of ${\mathrm{N}}_2$ but no electronic excitation of the ${\mathrm{N}}_2$ is observed. Arguments are presented which support the hypothesis that the known negative-ion resonances of ${\mathrm{N}}_2$ are involved in the detachment processes.

This experiment shows that scattering of light in laser-illuminated spherical targets at up to 56° was dominated by the stimulated Brillouin process. The energy and spectrum of both sidescattered and backscattered light were measured. When a target was irradiated by a one-beam Nd: glass laser (${\lambda }_L=1.054\mathrm{}$ μm) with a shaped pulse at an intensity of 7×${10}^{15}$ W/${\mathrm{cm}}^2$, the stimulated Brillouin sidescatter contained up to 55% of the incident energy.

It is shown that the cyclotron damping rate of the second harmonic is enhanced relative to the linear rate by a nonlinear resonance resulting from the finite wavelength of the pump wave. Applications to ion and electron cyclotron-resonance-frequency heating are considered.

Spherically converging positive and negative ion-acoustic pulses are investigated experimentally. Their behavior agrees with computer simulations based on the fluid model of plasma. Large positive pulses are identified as solitons.

With use of a $U$-tube device, substantial effects of a magnetic field on flowing superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at saturated vapor pressure have been observed. Data are presented that show marked magnetic distortions of the otherwise isotropic $B$-phase order parameter. Above a critical temperature the magnetic field appears to destroy the $B$ phase in favor of another type of state.

By use of field-ion mass spectrometry combined with retarding-potential-energy analysis the experimental evidence for electron-stimulated desorption of field-adsorbed helium and neon atoms as multiply charged positive ions is presented. The abundances of differently charged ions are measured and appearance-energy data are derived from the onsets of integral energy distributions. Within a one-dimensional potential-energy scheme, values for the interaction energy of multiply charged ions with the tungsten substrate are reported.

Cusplike behavior in the spin-lattice relaxation time of a probe molecule ($o$-${\mathrm{H}}_2$) is used to locate the transition temperature ($T_c$) to the quadrupolar glass phase of a host $o-{\mathrm{D}}_2-p-{\mathrm{D}}_2$ alloy for $p$-${\mathrm{D}}_2$ concentrations above 0.29. The values of $T_c$ obtained here are higher than those obtained from line-shape measurements. The spin-echo height is also strongly affected by the collapse of the correlation frequency spectrum near $T_c$.

Correlation-function exponents ${\eta }_{\perp }$ and ${\eta }_{\parallel }$ appropriate to the free-surface problem have been obtained by renormalization-group calculation to order ${\epsilon }^2$. By using the scaling relations ${\gamma }_1=\nu (2-{\eta }_{\perp })$ and ${\gamma }_{11}=\nu (1-{\eta }_{\parallel })$, expansions for ${\gamma }_1$ and ${\gamma }_{11}$ are obtained. These expansions are in agreement with the surface scaling relation $2{\gamma }_1-{\gamma }_{11}=\gamma +\nu$, but disagree with the relation ${\gamma }_{11}=\nu -1\mathrm{}$ due to Bray and Moore.

The leading terms in the magnetic equation of state are calculated for models with random fields and random uniaxial anisotropies for dimensionalities $d<\mathrm{}4\mathrm{}$. In the random anisotropy case we find a new low-temperature phase, in which the magnetization vanishes but the zero-field susceptibility is infinite, because of algebraically decaying correlations. No phase transition is found for the random field case.

The transition temperature of bis-tetramethyltetraselenafulvalene hexafluorophosphate ${\mathrm{}\left(\mathrm{TMTSF}\right)\mathrm{}}_2$P${\mathrm{F}}_6$ is found to decrease for pressures up to 12 kbar at a rate $\frac{d{T}_c}{\mathrm{dP}}=(-8\mathrm{}\pm 1)\times {10}^{-5\mathrm{}}$ K/bar. At 6.5 kbar, a coexistence of superconductivity ($T_c\sim 1.1$ K) and a metal-insulator transition ($T_{\mathrm{MI}}\sim 6$ K) is found.