A novel interpretation of nuclear rotation is presented. It is shown that, in and near the ground state, the proton and neutron deformed ellipsoids are rotating in opposite directions, whereas they rotate about almost the same axis in states of higher spins. This holds, quite similarly, for angular-momentum-projected Nilsson wave functions and for wave functions in the interacting boson model. The rotational energy can then be interpreted in terms of an inertial parameter against tilting of the proton rotation axis towards the neutron axis.

A three-dimensional wavelet analysis is employed to develop a new formalism for electronic structure calculations. The wavelet formalism provides a systematically improvable and tractable description of electronic wave functions and overcomes limitations of conventional basis expansions. The potential power of the wavelet formalism for ab initio electronic structure calculations is demonstrated by a calculation of 1s states for all the naturally occurring nuclei on the periodic table and the interaction energies of the hydrogen molecule ion.

Long lived (0.8 ms, 6 ms, and >3.8 s) states in ${\mathrm{CO}}^{2+}$ have been observed for the first time by monitoring beams of 75–300 keV ions in the ion storage ring ASTRID. It is the first experimental evidence that a doubly charged molecule can be stable on a time scale of seconds. The results are theoretically interpreted by means of a multichannel Schrödinger analysis based on ab initio computations of potential energy curves and off-diagonal spin-orbit couplings. This analysis indicates that ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }$(ν=0) accounts for the long lived component. The two decay components in the ms range probably derive from higher excited states in ${\mathrm{CO}}^{2+}$.

We give a recipe for how to create an arbitrary field state in a single-mode resonator.

The dephasing of excitonic localized states is investigated in ${\mathrm{CdS}}_{\mathit{x}}$${\mathrm{Se}}_{1\mathrm{-}\mathit{x}}$ mixed crystals at 2 K with low intensity femtosecond optical pulses. We observe a fast relaxation process which is first reported here. It is shown to be related to the creation of localized biexcitons via the exciton-biexciton transitions which act as an additional dephasing mechanism with a time constant ${\mathit{T}}_2^{\mathrm{ex}\mathrm{-}\mathrm{bi}}$ of 700 fs. The coherence between excitonic and biexcitonic states, which manifests by 800 fs period beats, is studied in detail. A simple model is presented which describes both the fast initial decay and the beating behavior.

We show that the presence of destructive interference due to quantum coherence at nuclear Zeeman level crossings can totally preclude γ-resonant absorption under appropriate conditions leaving resonant emission intact. The underlying principle can be demonstrated in a Mössbauer effect experiment and has broad consequences in the domain of gamma optics.

The nonlinear dynamics of two ions in a Paul trap is known to show chaos or condensation into a regular ‘‘crystal.’’ We present the first observations of frequency locking of two microspheres (diameter 10 μm) in a Paul trap, in close agreement with theoretical predictions. This system reproduces the main features of our earlier work on two-ion chaos. The phase space is fragmented, and chaotic transients can converge to several regular attractors. Damping, including laser cooling, can extinguish frequency-locked attractors, explaining their absence in ion trap experiments. Study of two weakly coupled circle maps shows that this is a general phenomenon when three frequencies are present.

Noncohesive granular materials driven by a vertically vibrated horizontal surface become unstable when the acceleration exceeds g. Then there is internal convective transport of materials balanced by continuous surface avalanches leading to an inclined surface. We describe studies above the onset to flow where new surface wave motions occur. The surface waves travel upward against gravity on the free surface. They occur only above minimum accelerations and dimensionless energies, and only with large vibration amplitude.

It has been found for the first time in experiments with an electron beam that space-charge waves can be generated not only in pairs. A single slow wave, a single fast wave, or combinations of the two waves with different amplitude and polarity relations have been produced experimentally in a space-charge dominated beam. Analytical solutions derived from one-dimensional fluid equations show the amplitude and polarity of each space-charge wave as a function of the initial perturbation parameters. The theory provides the correct interpretation of the experimental observations.

A new theory of microwave reflectometry is applied to turbulence measurements in the TFTR tokamak. Results indicate that in the main core of neutral beam heated plasmas in the supershot regime, the radial correlation length of density fluctuations is a weak decreasing function of heating power in the range 2–4 cm. Over the same interval of heating powers (0–14 MW), the level of density fluctuations is observed to steadily increase by more than an order of magnitude.

We present self-consistent simulations and analysis of the electron heating processes in an inductively coupled discharge. The results show that collisionless electron heating is predominant at pressures of 10 mTorr or less. The collisionless excitation mechanism is a warm plasma effect, analogous to the anomalous skin effect in metals.

For the first time a detailed surface structure determination is reported for an oxide film grown on a foreign metal substrate. Well-ordered iron oxide films were grown onto Pt(111) substrates and were identified by a dynamical low energy electron diffraction analysis to be magnetite, ${\mathrm{Fe}}_3$${\mathrm{O}}_4$. They form an unreconstructed polar (111) surface termination that exposes 1/4 monolayer of Fe ions over a distorted hexagonal close-packed oxygen layer and minimizes the number of dangling bonds. The surface also exhibits large relaxations that may be driven by electrostatic forces.

This paper shows that the nanostructures deposited at room temperature in scanning tunneling microscopy experiments are produced by mechanical contact between tip and sample. Gold mounds are deposited in gold substrates and it is observed that the current flowing between tip and sample is quantized and the resistance can be as low as 100 Ω.

A chain reptating through a high molecular weight polymer melt leaves a trace in the form of elastic distortions of an entanglement network. Neighboring chains can partially relax these elastic distortions by following this trace with some accuracy. Thus the memory of chain configuration is reproduced by other chains when the first one leaves the tube after time ${\mathrm{\tau }}_{\mathrm{dif}}$. The number of diffusion steps of duration ${\mathrm{\tau }}_{\mathrm{dif}}$ required to completely lose the memory of chain configuration grows with the molecular weight M of the chain as ${\mathrm{\tau }}_{\mathrm{relax}}$/${\mathrm{\tau }}_{\mathrm{dif}}$∼${\mathit{M}}^{1/3}$ in agreement with experiments, where ${\mathrm{\tau }}_{\mathrm{relax}}$ is the relaxation time of the melt.

Si(100) samples have been implanted with low doses (${10}^7$–${10}^9$${\mathrm{cm}}^{\mathrm{-}2}$) of MeV ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$ and ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$ ions. Deep level transient spectroscopy was used for sample analysis, and the generation of vacancy-related point defects is found to increase with increasing implantation temperature and to decrease with increasing ion dose rate. These results are in direct contrast to that for damage buildup at high doses (≥${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}2}$), and the effect is attributed to rapidly diffusing Si self-intersititials which overlap and annihilate vacancies created in adjacent ion tracks.

A one-dimensional gas of electrons interacting with long-range Coulomb forces [V(r)≊1/r] is investigated. The excitation spectrum consists of separate collective charge and spin modes. For arbitrarily weak Coulomb repulsion density correlations at wave vector 4${\mathit{k}}_{\mathit{F}}$ decay extremely slowly and are best described as those of a one-dimensional Wigner crystal. Pinning of the Wigner crystal then leads to the nonlinear transport properties characteristic of charge density waves. The results allow a consistent interpretation of the plasmon and spin excitations observed in one-dimensional semiconductor structures, and suggest an interpretation of some of the observed features in terms of ‘‘spinons.’’

Using the Kubo formula and a simplified Holstein model to calculate the Hall effect in the Anderson insulator, it is found that at low frequencies ${\mathrm{\sigma }}_{\mathit{x}\mathit{y}}$∝${\mathrm{\omega }}^2$ (with nonanalytical corrections). The coefficient is evaluated for strong localization and found to lead to the same order of magnitude as the usual classical result for the Hall coefficient.

We argue that for granular metals a sizable fraction of the grains becomes charged because the energy fluctuation of the highest-occupied level of each grain, as predicted by random matrix theory, is larger than the charging energy. We have computed the ground state density of states and the degree of ionization of granular metals. The density of states shows a Coulomb gap around the Fermi energy, produced by the long-range part of the Coulomb interactions, which should dominate transport properties at low temperatures.

We show that efficient tunneling of holes can be produced in double quantum wells with built-in piezoelectric fields by the photo- screening of that piezoelectric field. Our observation was made at low temperatures by comparing the behavior of ${\mathrm{Ga}}_{0.92}$${\mathrm{In}}_{0.08}$As-GaAs strained-layer double quantum wells grown along the (111) and (001) directions and tuning the densities of photoinjected carriers over several decades. Interpretation of the experimental data is made by comparison with Hartree calculations including the space charge effects. In addition to this, we also report the observation of many-body interactions at high photocarrier densities.

It is shown from rather general assumptions that the current density at low temperatures in the interior of a quantum Hall device follows the electric field distribution, smeared out over an appropriate localization length. This is not in conflict with Laughlin’s result that the total Hall current depends only on the potential difference between the edges, but must be used to complement it. It is illustrated by a discussion of edge and bulk currents for a Hall bar under the conditions of the integer quantum Hall effect. It is argued that these results can be extended to the fractional quantum Hall effect.