Three decoupled (ΔI=2) rotational bands have been observed to rise out of irregular spherical excitations in ${}_{51}{}^{117}{}_{}{}^{}\mathrm{Sb}$ at moderate spin. These bands are interpreted as resulting from low-lying π${\mathit{g}}_{7/2}$, π${\mathrm{d}}_{5/2}$, and π${\mathit{h}}_{11/2}$ valence orbitals outside the Z=50 closed shell coupled to the deformed [(π${\mathit{g}}_{7/2}$${)}^2$⊗(π${\mathit{g}}_{9/2}$${)}^{\mathrm{-}2}$${]}^{116}$Sn core state at the N=66 midshell. The valence orbitals do not significantly influence either the spherical or the deformed core shape; the latter is regulated by the β at which the π${\mathit{g}}_{7/2}$ and the intruder π${\mathit{g}}_{9/2}$ levels cross. Two strongly coupled (ΔI=1) bands involving [(π${\mathit{g}}_{7/2}$${)}^2$⊗(π${\mathit{g}}_{9/2}$${)}^{\mathrm{-}1}$] were also observed.

The energy region from the π threshold up to the Roper resonance N(1440) has been investigated in inelastic α scattering on hydrogen using α particles from SATURNE with a beam momentum of 7 GeV/c. In addition to projectile excitation, excitation of the ${\mathit{P}}_{11}$(1440 MeV) resonance has been observed for the proton, indicating a strong monopole excitation. From this a value of the nucleon compressibility of 1.4±0.3 GeV is extracted.

From the measured yield of δ electrons with energies between 3 and 8 MeV, emitted in the heavy-ion reaction Pb+Pb at 12 MeV nucleon incident energy, a very fast deceleration of the nuclei in the approach phase is inferred which is much faster than predicted by the microscopic one-body dissipation model. Since the deceleration time is smaller than or comparable to the thermal equilibration time, the dissipation process is non-Markovian and therefore memory effects have to be included. This is performed on the basis of dissipative diabatic dynamics, which describes elastoplastic properties. The new diabatic one-body dissipation model reporduces the fast deceleration and the long nuclear contact time.

Lithium atoms channeled in the nodes of an intense standing-wave radiation field are cooled to near the recoil limit by adibatically reducing the radiation intensity. The final momentum distribution has a narrow component with a root-mean-squared momentum of 2ħk in one dimension, where ħk is the momentum of a radiation-field photon. The data are compared with the results of a Monte Carlo simulation using a two-level atom model. This process may be useful for cooling and increasing the phase-space density of atoms confined in a magnetic trap.

A superthermal component in a metastable ${\mathrm{Kr}}^{+}$ krypton beam produced in a Kr gas discharge has been observed and studied. Evidence is presented that this fast component is due to dissociative recombination of ${\mathrm{Kr}}_2^{+}$, and that the excited Kr direct products of this reaction are predominantly in the 5s states. An effective method (time of flight) for studying the product states of dissociative recombination reactions is thus demonstrated.

Interactions of ${\mathrm{Li}}^{+}$ and ${\mathrm{Na}}^{+}$ with ${\mathrm{C}}_{60}$ molecules have been studied over the collision energy range from 0 to 150 eV. We observe insertion of the alkali-metal ions to form the endohedral [${\mathrm{LiC}}_{60}$${]}^{+}$ and [${\mathrm{NaC}}_{60}$${]}^{+}$ species, with energy thresholds of 6 and 20 eV, respectively. At higher collision energies, the excited [${\mathrm{NaC}}_{60}$${]}^{+}$ appears to relax mainly by loss of ${\mathrm{C}}_2$ units from the fullerene cage, yielding [${\mathrm{NaC}}_{60\mathrm{-}2\mathit{n}}$${]}^{+}$. For [${\mathrm{LiC}}_{60}$${]}^{+}$, escape of the ${\mathrm{Li}}^{+}$ competes effectively with ${\mathrm{C}}_2$ loss. For both ${\mathrm{Li}}^{+}$ and ${\mathrm{Na}}^{+}$, the signal for pure carbon fragment ions ${\mathrm{C}}_{60\mathrm{-}2\mathit{n}}^{+}$ increases sharply at ∼30 eV, which is attributed to thermionic emission.

Nonequilibrium steady-state flows governed by time-reversible equations of motion are described in terms of unstable periodic orbits. Important properties, such as transport coefficients and the multifractal spectrum, are related to the difference in probability of observing periodic orbits and their time reverses. We apply the theory to the periodic Lorentz gas driven by a constant external field and numerically calculate the conductivity.

The large dispersion of a phase-coherent medium, at a point of vanishing absorption, is applied to interferometric measurements of detuning between atomic and radiation frequencies. It is shown that, under certain conditions, the interferometer quantum-limited operation is determined by vacuum-fluctuation shot noise while the noise introduced by the interaction of the probe field with the phase-coherent atoms can be made negligible. As a possible application, an optical magnetometer is analyzed whose sensitivity is shown to be potentially superior to the present state-of-the-art devices.

Recently, in connection with the problem of Anderson localization of light, a new physical mechanism was considered for the decreasing of the diffusion coefficient, in which it is supposed that the velocity of energy transport, which appears in the diffusion constant D=${\mathit{v}}_{\mathit{E}}$${\mathit{l}}_{\mathrm{tr}}$/3, may be much smaller than the phase velocity. Using an exact definition of the diffusion coefficient and generalized Ward identity, we, however, show that in the low-density approximation ${\mathit{v}}_{\mathit{E}}$ coincides with the phase velocity.

Convection and fluidization in a vibrated bed of powder are reproduced in a numerical simulation. In the simulation, each particle of the powder, during a collision, has a viscoelastic interaction with the other colliding particle. Because of the discreteness of the particles, this elasticity causes convection. The critical values of fluidization and convection agree with experiments.

We present molecular dynamics simulations of granular material submitted to vibrations in a two-dimensional system. We find various types of convection cells, due either to the existence of walls or to spatial modulations in the amplitude of the vibration. The direction of the motion relative to the walls depends on shear friction. We measure the strength of the convection velocity and find a characteristic resonance frequency as in experiments. We propose an explanation for the mechanisms that are at the origin of the different motions.

We report the observation of a key feature of intermittency in the tokamak edge turbulence. The probability distribution functions of broadband plasma density and potential fluctuations in an Ohmically heated tokamak plasma are measured and shown to be non-Gaussian. The intermittency is observed on scales large compared to the dissipation scale and it is found to evolve during the flattop current phase of the discharge.

The difference in polarization for Rayleigh scattered radiation on spherically and nonspherically symmetric scattering objects has been used to obtain molecular species concentrations in plasmas of simple composition. Using a Rayleigh scattering diagnostic, the depolarized component of the scattered signal, proportional to the density of molecules in the plasma, was measured. This new method has been used to locally determine molecular species densities in pure nitrogen and pure hydrogen expanding plasmas. The results were used to obtain the dissociation degree of an expanding hydrogen plasma.

We use simulations to investigate the interaction of ultra-intense laser pulses with a plasma. With an intensity greater than ${10}^{18}$ W/${\mathrm{cm}}^2$, these pulses have a pressure greater than ${10}^3$ M bar and drive the plasma relativistically. Hole boring by the light beam is a key feature of the interaction. We find substantial absorption into heated electrons with a characteristic temperature of order the pondermotive potential. Other effects include a dependence on the polarization of the incident light, strong magnetic field generation, and a period of intense instability generation in the underdense plasma.

We have measured the x-ray structure factor S(Q) for ${\mathrm{SiO}}_2$ glass to 42 GPa in the diamond-anvil cell using new experimetnal techniques for studying amorphous materials at high pressures. Large changes in the first sharp diffraction peak of S(Q) with increasing pressure provide evidence for changes in the medium-range order of the glass (length scales of ∼4–10 Å). Average pair correlation functions at high pressure reveal significant changes in the nearest-neighbor geometry of the glass with compression. Between 8 and 28 GPa the coordination of Si increases, and at 42 GPa the value is close to six.

Electron intensities resulting from 4-keV ${\mathrm{Ar}}^{+}$ impingent on Ni{110}-p(1×1) and Ni{110}-p(1×2)-H surfaces exhibit sharp azimuthal- (δ) and incident- (α) angle anisotropies. The electron and scattered-Ar δ distributions are similar, indicating that electrons are emitted only from collisions whose impact parameters (p) are less than a threshold value (${\mathit{p}}_{\max }$). Comparison of the α-angle variations of the electrons and scattered Ar shows that the distance of closest approach corresponding to ${\mathit{p}}_{\max }$ is ≊0.3 Å. This corresponds to the sum of the radii of maximum radial-charge density of the L atomic shells of Ar and Ni.

Variable-temperature scanning tunneling microscopy has been used to observe molecular dynamics in the vicinity of order-disorder transitions in alkane monolayers at the interface between graphite and organic fluids. In crystalline lamellae adsorbed from solution a reversible increase in longitudinal molecular motion with increasing temperature is observed, until the amplitude becomes comparable to the lamella width and the order disappears. A two-dimensional smectic and a columnar phase are observed at the interface with a neat melt and a solution of a particularly long-chain alkane, respectively.

We study the x-ray response of an exactly solvable model of a Luttinger liquid coupled to a core level in one dimension. The power-law singularities in photoemission and x-ray absorption for a free Fermi gas are found to survive with modified exponents for a Luttinger system of finite compressibility. We also show that the singularities disappear in compressible systems even in the absence of a plasmon gap in the conduction band.

We consider the nonequilibrium quantum noise of electrical current in one-dimensional conductors, and clarify the mechanism that distinguishes macroscopic conductors from mesoscopic conductors. The noise does not become of the macroscopic type even when a strong dephasing is introduced. Macroscopic noise is obtained only when the energy of the total electron system is maximally dissipated when each electron traverses the conductor. Energy transfer from the electron system to other systems is therefore essential for noise suppression and for the noise to be macroscopic.

Soft-x-ray photoemission measurements of the bulk Si 2p core level in Si/${\mathrm{SiO}}_2$ overlayer structures show that hot-electron transport in ${\mathrm{SiO}}_2$ is essentially independent of temperature between 300 and 980 K. These results reveal a basic failure of the semiclassical Monte Carlo formalism to correctly model the strong electron-phonon interaction in ${\mathrm{SiO}}_2$ at electron energies >6 eV. The experimental data are shown to be consistent with the trends seen in quantum Monte Carlo transport calculations.