Magnetic evidence is presented for a first-order, structural transformation in the local order of a cobalt-base metallic glass. The transformation is centered at $T_0=180\mathrm{}°$ C and shows a scan-rate-dependent thermal hysteresis of $\Delta T=100\mathrm{}°$ C. A critical volume for nucleation of the transformation is estimated to contain approximately 200 atoms. The transformation appears in samples which show no microcrystallites greater than 30 Å and vanishes in samples with appreciable crystallinity. The observations are discussed in terms of model clusters of icosahedral, trigonal, and octahedral symmetry.

The small-polaron-like "self-trapping" of a surface electronic excitation plays a central role in electronically stimulated desorption. Two types of desorption, immediate and delayed, are possible. Calculations for hydrogen on silicon surfaces indicates that two-hole excitations produce immediate desorption for ${\mathrm{H}}^{+}$ while single holes may produce delayed desorption of neutral H.

A model of interacting random walks is proposed in which each new site visited has a weight factor $p$. For $1<~p<~\infty$, the model interpolates between purely random walks and self-avoiding walks. When $0<p<\mathrm{}1\mathrm{}$, the model describes attracting random walks (and also noninteracting random walks on a lattice with static traps), and shares some of the intriguing features of random walks on percolation fractals—e.g, dimension-independent exponents.

For Hermitian many-body systems, admissible functions for the velocity autocorrelation function form a certain invariant of time. This property originates from a basic recurrence relation. The exponentially decaying function cannot form an invariant and therefore cannot be admissible.

A band-crossing model based on a microscopically derived ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+ ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ potential and the Pauli principle is used to interpret data on ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$+ ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ reactions to eight inelastic channels. Structures observed in the cross sections are accounted for in all cases.

The authors have studied the question of whether pairs of neutrons and pairs of protons of the usual superfluid phases form a bound state to give rise to a superfluid condensate of "$\alpha$ particles." They indeed find indications for this to be the case from a BCS-like study for bosons using the proton-neutron interacting-boson model as well as from an even-odd effect in the number of pairs using experimental binding energies.

An investigation of the time-reversal-odd angular correlation $\hat{\sigma }·(\hat{J}\times \frac{\overrightarrow{\mathrm{p}}}{E})$ in ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ $\beta$ decay is reported. In this correlation, $\hat{\sigma }$, $\overrightarrow{\mathrm{p}}$, and $E$ are the $\beta$ spin, momentum, and energy, respectively, and $\hat{J}$ is the initial ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ spin. The sample was polarized by an atomic beam method and the $\beta$ polarization was measured with four Mott-scattering polarimeters. The magnitude $R$ of the angular correlation is found to be -0.079 ± 0.053, consistent with timereversal invariance. This result also implies $\mathrm{Im}\left(C_S{C_A}^{*}\right)=0.19\mathrm{}\pm 0.13$.

The usual Hugenholtz-Van Hove theorem for a Fermi system is extended to describe asymmetric nuclear matter. It has been further developed to describe finite nuclei. It is shown that this extended relation could be used as a basis for a new mass relation which has both the liquid-drop and single-particle features. Its success in predicting masses of exotic neutron-rich nuclei is demonstrated.

The $g$ factors of the $s$-band ${12}^{+}$ levels in ${}_{}{}^{164}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{166}{}_{}{}^{}\mathrm{Yb}$ were studied by measuring $\gamma$-ray angular distributions and internal conversion coefficients with use of a new electron spectrometer for the interband ${{12}_s}^{+}\to {{12}_g}^{+}$ transitions. The $g$ factors were deduced for the first time to be $g=0.07\mathrm{}\pm 0.03$ for ${}_{}{}^{164}{}_{}{}^{}\mathrm{Er}$ and -0.14±0.04 for ${}_{}{}^{166}{}_{}{}^{}\mathrm{Yb}$. These small values indicate clearly the rotation alignment of the $i_{\frac{13}{2}}$ neutrons for the $s$ band.

Energy spectra of protons emerging near the forward direction for 100-300-eV/u ${\mathrm{Ar}}^{+}$ beams incident on C${\mathrm{H}}_4$ were recorded. Cross sections for the capture of H atoms from C${\mathrm{H}}_4$ molecules into states lying in the vibrational continuum of the electronic ground state and into predissociative states of Ar${\mathrm{H}}^{+}$ molecules were measured as a function of projectile energy. Capture occurs via the Thomas double-scattering mechanism.

Measurements have been done for ejected-electron spectra from 5-27-keV ${\mathrm{He}}^{+}$ impact on He. A bandlike structure is observed in the higher-energy part of the spectra and theoretically reproduced as a result of molecular autoionization of ${\mathrm{He}}_2^{+}$. The value of autoionization width ${\overline{\Gamma }}_A$ is closely proportional to the energy of the incident ${\mathrm{He}}^{+}$ ion. This result leads to the conclusion that the dominant process for the observed molecular autoionization is due to the dynamical couplings.

With use of a Hamiltonian model system to represent ir laser excitation of a molecule it is shown that chaos is a fundamental aspect of this physical process. On average the chaos leads to a fluence-dependent absorption which previously was attributed to rapid statistical equilibration of energy in the quasicontinuum and was modeled by population rate equations. The origin of the chaos is the interplay of the pump mode's anharmonicity and intramolecular energy transfer.

Recent experimental results of Havey, Copeland, and Wang on the collisional redistribution of light by Na in Ar showed a dependence of the relative intensities of the Na $D_1$ and $D_2$ resonance lines on laser detuning. Calculations of these intensity ratios are reported here. The agreement between theory and experiment obtained here shows the importance of fine-structure transitions occurring during the dissociation of the excited-state molecule.

A fractal dimension $D_{F^{\prime }}$ of strange attractors is estimated as follows. Clusters of $n$ nearest-neighbor points are sampled from a time series; $D_{F^{\prime }}$ is found from ${\overline{R}}^{D_{F^{\prime }}}\sim n$ where $\overline{R}$ is the average cluster's radius. The estimation of $D_{F^{\prime }}$ is shown to be especially efficient for high dimensional systems.

The existence of a new type of surface wave in plasmas is demonstrated. These waves are intimately connected with the self-generation of magnetic fields in the laser-plasma interaction. The waves resemble waveguide modes in that a number of discrete modes can exist. The modes are localized to within a collisionless skin depth of the surface and, in the collisionless fluid limit, there is no restriction on the distance the waves can propagate.

Mixing times measured for a stirred critical binary liquid mixture are seen to vary dramatically with Reynolds number, Prandtl number, and the initial value of the order parameter. These variations are far too large to be explained by passive-mixing calculations; they also differ in significant respects from the active-mixing predictions of Ruiz and Nelson.

Study of a solid-on-solid model within the Migdal approximation leads the authors to conclude that the phenomenon of critical wetting cannot occur in the presence of long-range, van der Waals forces.

A model is proposed which shows both a surface-reconstructive phase transition and a faceting transition, depending on the molecular parameters. It involves a further generalization of Lieb's six-vertex problem.

By significantly extending the existing exact enumeration results, and by combining several independent analysis methods, the authors obtain accurate estimates of the leading "scaling" exponent and the amplitudes for the $d=3\mathrm{}$ linear-polymer radius-of-gyration problem. Specifically, they find that the mean square end-to-end distance of an $N$-step self-avoiding walk on an fcc lattice is given by the expression ${\rho }_N\sim A{N}^{2\nu }[1+\frac{B}{N^{\Delta }}+\frac{C}{N}]$ with $\nu \cong 0.5875$, $\Delta \cong 0.470$, $A\cong 1.05$, $B\cong \frac{-0.3\mathrm{}}{A}$, and $C\cong 0.25$.

Uniaxial stress has been used with transient spectroscopy to study the level at $E_c-0.17\mathrm{}$ eV in neutron-irradiated silicon. The defect symmetry, observed stress-induced electronic redistribution, and preferential stress-induced defect orientation have been determined and the reorientation activation energy has been measured. All of these effects are consistent with the $A$ center.