A chemical-equilibrium model for plasma-enhanced chemical vapor deposition of a-Si:H is developed to interpret the irregular incorporation of As and P. The model shows that the irregularity occurs only for nondoping impurities; their distribution coefficient is inversely proportional to the rf plasma power, which leads to the large As concentration enhancement observed under low-power growth conditions. A configuration-energy diagram is proposed to account for this enhancement based on the preferential formation of stable, inactive As in a configuration other than the usual interconverting three- and fourfold-coordinated sites.

To explore the generation mechanism of spontaneously ordered structure, a ${\mathrm{Ga}}_{0.7}$${\mathrm{In}}_{0.3}$P alloy grown on a ${\mathrm{GaAs}}_{0.6}$${\mathrm{P}}_{0.4}$ substrate is examined by transmission electron diffraction. Contrary to the thermodynamic prediction using first-principles theory, in which luzonite-type and/or famatinite-type ${\mathrm{Ga}}_3$${\mathrm{In}}_1$${\mathrm{P}}_4$ structures are expected, a CuPt-type ordered structure is found. The probable atomic arrangement is a (${\mathrm{Ga}}_{0.7\mathrm{-}\mathrm{\eta }}$${\mathrm{In}}_{0.3+\mathrm{\eta }}$P)(${\mathrm{Ga}}_{0.7+\mathrm{\eta }}$${\mathrm{In}}_{0.3\mathrm{-}\mathrm{\eta }}$P${)}_1$ ordered structure. A spontaneously generated CuPt-type ordered structure in the GaInP system is not a consequence of thermodynamic stability.

We have investigated the subresonant optical response of the polydiacetylene PTS using stimulated inverse Raman spectroscopy. The data exhibit energy-dependent line-shape variations which are caused by the optical Stark effect on the exciton-phonon and exciton–ground-state transitions. These are the first observations of both phonon-mediated and excitonic optical Stark effects in a 1D conjugated polymer. Excellent agreement is achieved between the data and our calculations using a theory of phonon-mediated changes in susceptibility.

The nonequilibrium occupation of multiple defect states in inhomogeneously illuminated crystals is demonstrated to have dramatic and previously unexpected consequences for the photorefractive behavior of electro-optic semiconductors. By using a simple screening formalism, we show for the first time that the standard photorefractive effect can be partially or entirely quenched. This nonequilibrium screening is observed in the thermally stimulated relaxation of diffraction efficiencies in four-wave mixing experiments performed on semi-insulating InP.

We report on measurements of the thermal conductivity ${\mathrm{\kappa }}_{\mathrm{T}}$ close to the Peierls transition temperature ${\mathrm{T}}_{\mathrm{P}}$ in ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_3$ and (${\mathrm{TaSe}}_4$${)}_2$I. In both cases there is an enhancement of ${\mathrm{\kappa }}_{\mathrm{T}}$ that peaks at the transition. Simultaneous measurements of the specific heat suggest that the anomalous behavior is a result of mode occupation rather than changes in electron- or phonon-scattering processes.

We report a strong enhancement of the optical responsivity in GaAs/AlGaAs multi-quantum-well infrared detectors. This is explained by a resonant increase in the hot-electron mean free path as a result of the coherent transmission resonances in the continuum states above the energy barriers of the superlattice.

We obtain a hierarchy of effective Hamiltonians which allow for a unified treatment of the fractional quantum Hall effect and a gas of fractional-statistics particles (anyons) in two dimensions. Anyon superconductivity is the analog of the fractional quantum Hall effect. For rational statistics parameter ${\alpha }_s$=P/Q with PQ even, Q anyons bind forming a charge Qe superfluid.

The problem of tight-binding electrons in a two-dimensional lattice with a magnetic flux p/q in each plaquette is investigated for p=0,1,3; q=2,3,4,6,8. For fixed electron filling, ν, the total kinetic energy of the electrons has an absolute minimum for one flux quantum per particle, i.e., when p/q=να, where α is 1,(1/2,2 for square, triangular, and honeycomb lattice.

In the Raman spectra measured on ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_7$ single crystals there are continua of electronic origin. It is proposed that in addition to the intraband scattering there is an interband contribution due to the charge transfer between the bridging oxygen and the plane, which is strongly coupled to the 330-${\mathrm{cm}}^{\mathrm{-}1}$ phonon. We suggest that the entirely gapless feature of the spectra with ${\mathrm{B}}_{1\mathrm{g}}$ symmetry is a probe of nodes in the superconducting gap. The compatible d- and p-pairing states are listed.

We establish three results on the 3D Schrödinger equation with a potential having no spherical symmetry: the existence of a Wiener-Hopf factorization of the scattering operator, a method to recover the potential from the scattering data, and the existence of the 3D Jost operator.

The reversible one-species diffusion-limited reaction X+X⇄X is solved exactly in one dimension. We find that the asymptotic approach to equilibrium exhibits a sharp (second-order-type) transition depending on the initial density ${\rho }_0$. The exponential relaxation time becomes infinitely long as ${\rho }_0$→0. .AE

We propose definite experiments to provide realizations of a number of important models in the field of quantum chaos. These models share the feature that they are driven impulsively in time, i.e., kicked. In quantum language, a kick drives the system from one energy level to a neighboring one. The most fundamental question is whether localization occurs, i.e., whether eventually the system is driven far from its initial level or not. The most straightforward realizations are in optical fibers where the language of modes and propagation constants replaces quantum terminology.

The eigenspectrum of the critical anisotropic Heisenberg model (or XXZ model), with arbitrary spin S in its disordered-ferroelectric regime (0≤γ≤π/2S) is solved by the Bethe-Ansatz method. The amplitudes of the leading finite-size corrections are calculated analytically and numerically. Using conformal invariance we give exact results for the conformal anomaly and scaling dimensions. Our results indicate that, for all spin S, the critical behavior is governed by a conformal field theory with central charge c=1.

A new scenario of cosmic strings is presented which is free from the gravitational-radiation constraints imposed on their line density by the primordial nucleosynthesis and the timing data of a millisecond pulsar. In this scenario the phase transition is induced nonthermally during the inflation so that it is not necessary to assume Friedmann-Robertson-Walker universe in thermal equilibrium at the outset.

With the aim of overcoming the present energetic difficulties in getting type-II supernovae explosions, we present a possible scenario based on strange-matter formation. The observational expectations of this picture are discussed and the predictions of the model for SN 1987A neutrinos and remnant pulsar are examined.

An analysis of $Z^0$→$e^{+}$$e^{\mathrm{-}}$ and $Z^0$→${\mu }^{+}$${\mu }^{\mathrm{-}}$ data from the Collider Detector at Fermilab in p¯p collisions at √s =1.8 TeV yields a mass of the $Z^0$ boson of $M_Z$=90.9±0.3 (stat+syst)±0.2 (scale) GeV/$c^2$ and a width of ${\Gamma }_z$=3.8±0.8±1.0 GeV.

We have measured the mass of the Z boson to be 91.11±0.23 GeV/$c^2$, and its width to be ${1.61}_{\mathrm{-}0.43}^{+0.60\mathrm{}}$ GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.62±0.23 GeV, corresponding to 3.8±1.4 neutrino species.

We show that recent actions for a single self-dual antisymmetric tensor field in 4k+2 dimensions lead to the same one-loop gravitational anomalies as obtained a few years ago by Alvarez-Gaumé and Witten, who conjectured the necessary Feynman rules in the absence of an action principle.

By using coherent-state path integrals I provide a derivation of a two-dimensional chiral boson action which is equivalent to a free Weyl fermion.

The A dependence of the (e,e’p) reaction in the quasifree region has been measured at an average $Q^2$ of 0.33 (GeV/c${)}^2$ for targets of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$. The outgoing proton kinetic energy was 180±30 MeV. By comparing the ratio of (e,e’p) coincidence to (e,e’) singles yields, average proton transmissions are obtained for each target. The resulting ‘‘mean free path’’ or, more precisely, the attenuation length for protons in the nucleus is significantly longer than expectations based on the free nucleon-nucleon cross section.