Strong ground-state ($p$,$t$) transitions in nuclei of neutron number ≈ 50-82 are found to show anomalous analyzing powers which cannot be reproduced by direct one-step distorted-wave Born-approximation calculations at all. The anomalies are explained as an interference between ($p$,$d$) ($d$,$t$) sequential processes and the one-step process. The cross section of the sequential processes is as large as that of the one-step process in the $L=0\mathrm{}$ ($p$,$t$) reactions. The neutron-number dependence of the anomalies is interpreted.

Differential cross sections ${\sigma }_{{\pi }^{\pm }}\left(\theta \right)$ for elastic and inelastic scattering of 162-MeV pions from ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ were measured at momentum transfers between 0.6 and 2.1 ħ · ${\mathrm{fm}}^{-1\mathrm{}}$. For two inelastic transitions, enhancement of ${\sigma }_{{\pi }^{-}}$ over ${\sigma }_{{\pi }^{+}}$ and of ${\sigma }_{{\pi }^{+}}$ over ${\sigma }_{{\pi }^{-}}$ were observed which are consistent with the values for pion scattering from free nucleons. The results are discussed qualitatively in terms of simple shell-model and weak-coupling-model configurations.

This letter presents a study of a simple way to relax the frozen-configuration assumption in the calculation of the real part of the nucleus-nucleus potential. The proposed model allows the thickness of the surface layer of each nucleus to vary from the outer side to the interacting side giving rise to polarized shapes which simulate a neck formation. The result is compared to other potentials available in the literature.

We calculate the average nucleon-nucleus potential from the Dirac-Hartree model, extended to positive energy. The sole input is a one-boson-exchange nucleon-nucleon interaction which reproduces ground-state properties. We obtain fair agreement with empirical values. Between 170 and 400 MeV, the calculated potential is repulsive in the nuclear interior but still attractive at the surface. This shape is related to the scalar and vector nature of the exchanged bosons.

We describe both the theory and first experimental realization of a new light-scattering method for studying nonspherical particles in dilute solution. It is based on measuring the cross correlation of signals from two spatially separated detectors each of which receives light from the same small number of scatterers. Possible reasons for observed differences between experiment and theory are discussed.

The impact-parameter dependence of $K$-shell-vacancy sharing has been investigated with collisions of H-like S (${\mathrm{S}}^{15+}$) on Ar. An oscillation of the vacancy-sharing ratio with impact parameter has been found which is due to the interference of components of the vacancy-sharing amplitude on incoming and outgoing parts of the collision.

Fluorescent spectra for two, three, four, and five atoms in a volume of dimension less than the resonant wavelength have been obtained numerically. For high laser intensities, resonances displaced from line center by twice the Rabi frequency are found in addition to the usual Stark sidebands.

We propose a simple model to incorporate pumping process in the initial evolution of superfluorescence. The calculated initial tipping angle is closest, among various predictions, to the very recently measured value by Vrehen and Schuurmans. We also calculate the quantum fluctuations to account for the shot-to-shot variations in experimental results. Additional experiments with varying pumping duration are suggested to further test the validity of our model.

The Alder-Wainwright effect for the velocity autocorrelation function is small and difficult to observe in a system of neutral particles but is more prominent in a strongly coupled plasma. The pure electron plasma recently produced by Malmberg and deGrassie provides an opportunity to observe the Alder-Wainwright effect experimentally. We speculate on the behavior of the velocity autocorrelation function for this system.

The transverse instability of plane Langmuir solitions is reinvestigated with respect to the effects of coupling to electromagnetic fields. The instability is shown to persist and the growth rate is calculated to first order in the transverse wave number. Slow solitons are subject to a new type of instability, which is effective for extremely long-wavelength perturbations.

The ESR spectrum of the ${\mathrm{F}}_3^{2-}$ dianion in LiF ($V_t$ center), observed by Cohen, Känzig, and Woodruff, is analyzed using a semiempirical valence-bond wave function. The results (${\mathrm{F}}_3^{2-}$ has a ${}_{}{}^3{}_{}{}^{}\Sigma _{\mathrm{u}}^{}{}_{}{}^{}$ ground state with internuclear distance $R_{\mathrm{FF}}=3.4\mathrm{}{a}_0$ and 17% ionic character for the center F atom) strongly suggest this center is an interstitial F atom interacting with two nearest-neighbor lattice anions.

A lifetime of 13 μ s is measured for the paraexciton in ${\mathrm{Cu}}_2$O at 10 K. The orthoexciton lifetime is shown to be limited by ortho-para transfer rate. A high density of paraexcitons is generated, leading to deviations from classical statistics.

Optical homogeneous linewidths of the ${}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}-{}_{}{}^3{}_{}{}^{}H_4^{}{}_{}{}^{}\mathrm{}\left(1\right)\mathrm{}$ transition of ${\mathrm{Pr}}^{3+}$ in Be${\mathrm{F}}_2$ and Ge${\mathrm{O}}_2$ glasses reveal an anomalously smooth quadratic dependence on temperature from 8 to 300 K. The low-temperature behavior is consistent with a recent model of Lyo and Orbach involving an interaction with a single two-level system but the smooth quadratic behavior at all temperatures has deep consequences for the relative roles played by the ordinary phonons and the two-level system in line broadening.

This Letter proposes a scheme for obtaining the $d$-electron energy-band parameters to be used in a simple analytic model of the alloy heat of formation, $\Delta H$. The scheme employs, as an intermediate step, the equalization of the local chemical potentials of the two sites. Calculations for $3d$, $4d$, and $5d$ metal alloys yield $\Delta H$ in accord with experimental trends, but, unlike earlier estimates, with $d$ charge transfer in the direction indicated by experiment.

The valence bands and core levels of the metallic glasses ${\mathrm{Pd}}_{100-x}{\mathrm{Zr}}_x$ ($65<~x<~75$) and ${\mathrm{Cu}}_{100-x}{\mathrm{Zr}}_x$ ($40<~x<~70$) and the polycrystalline pure components have been measured by ultraviolet photoelectron spectroscopy ($h\nu =21.2\mathrm{} \mathrm{and} 40.8$ eV) and x-ray photoemission spectroscopy ($h\nu =1253.6\mathrm{}$ eV). The valence-band spectra of the alloys are characterized by a large shift of the Cu and Pd $d$-band peaks to higher binding energies and a complete change of the shape of these bands to Gaussian-like peaks. This behavior is in contrast to crystalline $d$-band alloys studied to date.

Erbium nuclei around $N=86\mathrm{}$, which are weakly collective at spins below about $40\hslash$, have been studied at higher spin using techniques recently developed for studying continuum $\gamma$ rays. A strong collective structure appears to develop above spins around $40\hslash$, which can expalin why no discrete lines have been observed beyond $36\hslash$. The similarity of the spectra for heavier and lighter erbium nuclei at spins $\mathrm{}(40-60)\mathrm{}\hslash$ suggests the same shape (prolate) for both.

Shape resonances in molecular photoionization are shown to induce strong coupling between vibrational and electronic motion over a spectral range several times broader than the resonances half-width. This coupling is manifested by large deviations from Franck-Condon intensity distributions and strong dependence of photoelectron angular distributions on the vibrational state of the residual ion. These effects are illustrated for the $3{\sigma }_g$ photoionization channel of ${\mathrm{N}}_2$.

The probability rate of photon-catalyzed molecular predissociation (or unimolecular reaction) is shown to increase by many orders of magnitude in the case of (near-) resonance of the laser frequency with intermediate discrete molecular states. As a result, the photocatalytic effect is important even at unexpectedly low laser power. Both the resonant and the nonresonant photocatalytic effects can be demonstrated by experiments with alkalimetal dimers (e.g., ${\mathrm{Na}}_2$).

Motivated by the recent experimental study of Rayleigh-Bénard convection performed by Gollub and Benson, I have introduced a periodic modulation into a 14-variable convection model which was studied previously. The induced noise shows a threshold in the driving amplitude, and occurs for various values of the modulating frequency. For the frequency range studied by Gollub and Benson qualitatively similar behavior to that which they reported is found.

The wavelengths, amplitudes, frequencies, and spatial distributions of driven lower-hybrid wave fluctuations are studied in the Alcator tokamak with use of C${\mathrm{O}}_2$-laser scattering. It is found that for incident microwave power densities from 0.4 to 4.5 kW/${\mathrm{cm}}^2$ the wave amplitudes are nearly independent of the relative phase of the electric fields at the exciting waveguides. The waves are not localized in resonant cones and they have frequency widths of from 0.5 to 6 MHz.