A capacitor-model plasma simulation and test-particle methods have been utilized to study energy distributions of electrons heated by resonance absorption of intense laser light. Certain subtle properties of the resonantly excited field which introduce a random character to the heating and have a controlling influence on the shape of the distribution have been identified.

A pure electron plasma has been confined in cylindrical geometry for many minutes. Confinement scalings with background pressure and magnetic field show that the maximum confinement times, while long, are 100-5000 times shorter than the limit set by electron-neutral collisions.

Temporally resolved sub-kiloelectronvolt x-ray emission pulses have been obtained from disk targets illuminated with 1.06-μm wavelength laser light at 5×${10}^{14}$ W/${\mathrm{cm}}^2$. Striking variations in the x-ray pulse shape from Be, Ti, Sn, Au, and U targets indicate the onset of strongly inhibited electron thermal conduction during the rise of the laser intensity. The laser intensity threshold for this strong inhibition is found to increase with target atomic number $Z$.

On Ir(110), tungsten adatoms move preferentially across [$1\overline{1}0$] channels rather than along them, as observed on other channeled planes. The jump mechanism underlying this anomalous behavior has been tested in an atom probe. It is found that after cross-channel motion, an iridium adatom is left on the iridium surface rather than the tungsten originally deposited. These observations provide the first experimental evidence for atomic diffusion on a metal by exchange of the adatom with an atom from the substrate.

A gradient in the concentration of adsorbed ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, produced by a current of ripplons, has been observed in heat-conduction measurements on the surface of superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. The ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ spreading pressure and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-ripplon collision rate have been determined from the data.

Monolayer thicknesses of Al are observed at Au-GaAs(110) interfaces modulate the relative Ga to As diffusion into Au by over an order of magnitude. This new phenomenon at compound semiconductor/metal interfaces reveals a systematic relationship between the local atomic bonding and the extended chemical structure of the interface.

Present results on CsCl-type and earlier work on NaCl-type solid ionic conductors have indicated that the relaxation of the lattice associated with vacancy formation is outward (i.e., the formation volume is greater than the molar volume). This is in qualitative disagreement with available theoretical calculations which show that the relaxation should be inward for all models of ionic vacancies investigated.

We present a mechanism for the resonance near the $3p$ threshold in the photoemission associated with the two-hole bound state in metals such as Cu and Zn. It is based upon the strong interaction between the $4s-4p$ conduction-band electrons and the two bound holes (the $3d^8$ configuration) resulting from the super Coster-Kronig decay of the $3p$ core hole. This effect also occurs in Ni but is not dominant.

Ab initio extended muffin-tin orbital calculations are presented for trans-polyacetylene heavily doped with As${\mathrm{F}}_5$, As${\mathrm{F}}_6$, Sb${\mathrm{F}}_6$, or P${\mathrm{F}}_6$. For the hexafluoride dopants, As${\mathrm{F}}_6$ and Su${\mathrm{F}}_6$, hybridization of metal $s$ states with polymer $\pi$ states produces a partly filled metallic band. This provides a band model of metallic conductivity within and between chains consistent with anisotropic electric conductivity. This model should also apply to other doped conjugated polymers.

Bulk superconducting fluctuation contributions to rounding of the electrical resistivity of Al just above $T_c$ are demonstrated to be at least 5 to 10 times smaller than claimed recently by Sinvani, Levy, and Greenfield. Metallurgical artifacts provide a more plausible explanation for all of the measured rounding.

The electronic structure and vibrations of an adsorbed hydroxyl (OH) species are identified and characterized for the first time on a transition-metal surface. In this study of water's interaction with clean Pt(111) in ultrahigh vacuum, water adsorbed at 100 K desorbs at 180 K without appreciable dissociation. However, in the presence of adsorbed atomic oxygen, water dissociates above 150 K to form adsorbed hydroxyl species. The O-H axis appears to be bent relative to the surface normal.

The reaction exoergicity of K + HgBr→KBr + HgBr ($\Delta D_0=-0.86\mathrm{}\pm 0.09$ eV) plus the energy of a photon of $\lambda <606\mathrm{}\pm 26$ nm provides sufficient energy to open the channel to HgBr* ($\tilde{B}{}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}$). Although neither reagents nor products absorb near 595 nm, luminescence at 500 nm is observed from the crossing region of beams of K, Hg${\mathrm{Br}}_2$, and photons ($\lambda \sim 595$ nm). This emission is attributed to HgBr* formed by light absorption during reactive collision. The cross section is ∼ ${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$ at ∼ 2 MW/${\mathrm{cm}}^2$.

The contribution of lowest-order electromagnetic (or weak) corrections to quark masses in quantum chromodynamics is considered. It is found that each contribution to the running mass is calculable from physics well below the grand unified scale, as long as the number of quark flavors $n_f$ is greater than or equal to eleven. The renormalization-group expression for the running mass is also derived, by use of Dyson's equation for the self-energy of the quark.

Order-${{\alpha }_s}^2$ corrections to the annihilation of $e^{+}{e}^{-}$ into hadrons are computed analytically. We briefly discuss the technique, which involves the extension to noninteger dimensions of Chebyshev expansions. In the energy range 15-30 GeV (five flavors) we find $R=3\mathrm{}\Sigma {e_Q}^2\{1+\frac{{\alpha }_s\mathrm{}\left(q\right)\mathrm{}}{\pi }-0.94\mathrm{}{\left[\frac{{\alpha }_s\mathrm{}\left(q\right)\mathrm{}}{\pi }\right]}^2+\dots \},$ where ${\alpha }_s$ is the momentum-space subtracted strong-coupling constant. Our result agrees with that of Dine and Sapirstein, and Chetyrkin, Kataev, and Tkachov.

This paper describes a search for weakly or semistrongly interacting particles produced in the collision of 4.9×${10}^{18}$ 28-GeV protons with a thick copper and brass beam stop. 104 events have been observed; their characteristics are similar to those produced by neutrinos arising from proton interactions in a 15-cm-thick brass target. However, compared to the number expected, an excess of 48 events is found with uncertainties of ±10 (statistical) and ±12 (systematic). At most ten events (68% confedence level) are attributable to beam losses.

Experiments on ${}_{}{}^{160}{}_{}{}^{}\mathrm{Yb}$ indicate three negative-parity bands up to $I>~21\hslash$. All three experience a band crossing around a frequency $\hslash \omega =0.36\mathrm{}$ MeV, a value intermediate to those of the first and second yrast backbends. The $i_{\frac{13}{2}}$ band in ${}_{}{}^{161}{}_{}{}^{}\mathrm{Yb}$ is observed up to ${\frac{49}{2}}^{+}$; it also has a strong upbend at this intermediate frequency. The fingerprint of a band crossing based upon the crossing frequency and gain in aligned angular momentum is demonstrated and the results compared to cranking-model calculations to suggest quasiparticle assignments for the bands.

The results obtained by series-analysis techniques applied to the time evolution of the inviscid Taylor-Green vortex support the conjecture that vortex lines may be stretched an infinite amount in a finite time.

When $\frac{Z{v_0}^2}{{v_e}^2}\gtrsim 1$, inverse bremsstrahlung results in a non-Maxwellian velocity distribution for which the absorption is reduced by up to a factor of 2 compared with the Maxwellian distribution usually assumed. Transport and atomic processes are also altered. Especially in materials with $Z\gg 1$, this is significant at lower intensities than for the well-known nonlinearity for which the measure is $\frac{{v_0}^2}{{v_e}^2}$.

High-resolution images of suprathermal x-ray emission from laser-imploded fusion targets have been recorded. The images show the spatial distribution of the relatively cold pusher material during the early stages of target implosion. There is evidence of an early, asymmetric breakup of the pusher shell.

With use of the characteristic turning-point radii of the first-principles nonlocal density-functional atomic pseudopotentials, a successful topological prediction of the crystal structures of 495 binary $\mathrm{AB}$ compounds of transition and simple elements is obtained.