In search of an explanation for the peculiar [D]/[H] distribution in the solar system a mechanical effect of light on ${\mathrm{H}}_2$O vapor is investigated which combines great isotope selectivity with mechanical transport, viz. light-induced drift. Results of laboratory experiments are presented. They show that in the protosolar nebula this effect may have been an important mechanism for the relative enrichment of deuterium on the inner planets of our solar system. Gravitational redshift provides a direction for this mechanism. The effect of light pressure is found to be 2 orders of magnitude smaller.

We present the total ionization cross section and spin asymmetry at projectile energies ranging from threshold to 500 eV for electron-impact excitation of atomic hydrogen. They are calculated using the convergent close-coupling formalism of Bray and Stelbovics [Phys. Rev. A 46, 6995 (1992)]. Both observables are found to be in complete quantitative agreement with measurements over almost the entire energy range. This is the only electron-atom scattering theory that is able to achieve this result to date.

Dielectronic recombination for ${\mathrm{Br}}^{33+}$ has been measured for channeling along a 〈110〉 axis in Au. In contrast to the recent surprising observation by Belkacem et al., both the resonance width and strength are in agreement with the predicted values for an electron gas with a density corresponding to the average electron desity in 〈110〉 channels of Au.

Experimental evidence is reported for the efficient ${\mathrm{H}}^{\mathrm{-}}$ formation in UV laser irradiated ${\mathrm{H}}_2$.

We have formed highly polarized muonic helium by stopping unpolarized negative muons in a mixture of unpolarized gaseous He and laser polarized Rb vapor. The stopped muons form muonic He ions which are neutralized and polarized by collisions with Rb. Average polarizations for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ of (26.8±2.3)% and (44.2±3.5)% were achieved, representing a tenfold increase over previous methods. Relevant cross sections were determined from the time evolution of the polarization. Highly polarized muonic He is valuable for measurements of the induced pseudoscalar coupling ${\mathit{g}}_{\mathit{p}}$ in nuclear muon capture.

We propose a technique for the preparation of Fock states of a harmonic oscillator strongly coupled to a single two-level atomic transition based on the observation of quantum jumps. Examples are taken from the fields of cavity QED and ion trapping, where photon number states and number states of the quantized atomic motion may be prepared, respectively.

Neon gas excited by 800-nm laser pulses (15 mJ, 125 fsec) at an intensity near ${10}^{15}$ W/${\mathrm{cm}}^2$ generates harmonics up to 109th order. The appearance of successively higher harmonics as the laser intensity is increased is compared to recent calculations of the strong-field atomic response. Blueshifting of the laser and harmonic wavelengths indicates a small degree of ionization until the threshold for the highest harmonic (>91st) is reached.

It is shown that a resonant interaction between a laser beam, a standing light wave, and a relativistic electron beam can be built up in a Lorentz frame different from that of the laboratory. The conditions for which external electromagnetic radiation with wavelength shorter than that of the laser pump field can be amplified via an electron-scattering process of the Kapitsa-Dirac type are then determined. The linear gain of this device is estimated and the possibility of building an ‘‘optical-wiggler’’ free-electron laser working from the IR to the VUV range is investigated.

We present experimental results of harmonic generation using a 1-ps ${10}^{15\mathrm{-}}$W/${\mathrm{cm}}^2$ Nd-glass laser. We see up to the 29th harmonic in Xe, 57th in Ar, and at least up to the 135th harmonic in Ne (160 eV), being then limited by our monochromator’s resolution. The conversion efficiencies in Xe, Ar, Ne, and He are compared and different ways of optimizing the number of photons by defocusing the laser beam or increasing the density are discussed.

We have experimentally verified the prediction that a homogeneous steady state of an activator-inhibitor system can be destabilized by a differential flow of the key species, rather than by their differential diffusivity for Turing instability. Traveling waves are generated by a flow of Belousov-Zhabotinsky reactants through a tube containing ferroin immobilized on a cation exchanger. Without flow the system resides in a homogeneous steady state. This mechanism of spatiotemporal pattern formation avoids the restrictions of the Turing instability on the diffusion coefficients and can thus be expected to operate in a larger class of chemical, physical, and biological systems.

A discrete model of random transport is analyzed both numerically and theoretically. Non-Gaussian fluctuations are always realized when a finite portion is transported at a time. Gaussian and power-law fluctuations appear in extreme limits.

A new class of nonlinear traveling-wave solutions of the relativistic cold-fluid model are presented for a system consisting of a relativistic cold electron beam propagating through a helical wiggler magnetic field. The solutions, which are in the form of isolated soliton pulses of coupled electromagnetic and plasma waves, are obtained numerically. They represent possible nonlinear saturated states of the free-electron-laser instability and may also have useful applications in particle acceleration schemes.

For a given rf cavity voltage, there is a maximum attainable peak current in an ion storage ring. This occurs when the electric field from the beam space charge is balanced by the field from the rf cavity. In this limit, the linear charge density distribution is parabolic and incoherent synchrotron motion is suppressed. The beam energy spread cannot be determined from the bunch length which depends only on the beam current and rf voltage. This has been observed using the high energy electron-cooling system at the Indiana University Cyclotron Facility.

Plasmas were generated by 400 fs KrF laser pulses at intensities of ∼${10}^{17}$ W ${\mathrm{cm}}^{\mathrm{-}2}$ on aluminum targets. Reflectivity and x-ray emission were measured as a function of laser polarization, angle of incidence, and intensity. For the same absorbed intensity, p-polarized laser light is up to a factor of 5 more efficient in generating x rays (>0.5 keV) than s-polarized light. These results show the importance of an additional absorption process, besides collisional absorption, for short scale length plasmas that is effective for p-polarized light only and has the characteristics of resonance absorption.

The physics limiting the density of a cold non-neutral plasma is presented. It is shown that when a flow has no strain, the instantaneous maximum number of charges that can be stored within a fixed boundary is equal to the total magnetic field energy within divided by the relativistic rest energy of a single charge. A higher limit can be supported by the presence of a deviatoric strain in the flow. Brillouin flow equilibria with arbitrarily high values of the Brillouin ratio, leading to the possibility of pure inertial-electrostatic confinement of non-neutral plasmas, are demonstrated.

The first experimental measurements of near-forward scattering from a plasma at wavelengths near the pump wavelength are presented. Simultaneous, time-resolved spectra from several oblique forward angles show the characteristic wavelength shift associated with scattering from an ion wave. Energy measurements show that forward scattering is stronger than backscattering. The angular distribution of forward scattered energy is in qualitative agreement with the simple convective-instability theory of stimulated Brillouin scattering.

We observe an increase in plasma density and a significant reduction in fluctuations with bias electrode in a pure toroidal plasma having no poloidal magnetic field. The improved toroidal plasma behavior is found to depend upon the radial currents driven by positive biasing of a ring electrode. Although biasing establishes a radial electric field at the edge, we see suppression of fluctuations and density rise in the central core region of the plasma.

The spectral dependence of the F-center formation efficiency in KCl and KBr was measured in the photon energy region of the Cl K and Br K edges at liquid-helium temperature. No discernible increase in the F-center formation efficiency was observed at either the Cl or Br K edge.

We present experimental and theoretical evidence for the creation of inversion domain boundaries (IDB’s) at structural phase transitions in III-V semiconductors. A novel use of anomalous high-pressure powder x-ray diffraction with an image plate area detector allows for the study of weak difference scattering, the absence of which is attributed to IDB’s. As a test of this, ab initio total energy pseudopotential calculations, including both ionic relaxation and boundary layer expansion, have been performed on a particular type of possible defect—a (110) IDB in InSb.

Crystalline, confined ionic systems exhibit well defined phase transitions as a function of the anisotropy of the confining potential. The transitions from one to two dimensions, from two to three, and back from three to two have been investigated as a function of this anisotropy with molecular dynamics simulations. The anisotropy at which such transitions occur seems to be proportional to a power of the number of confined ions.