We demonstrate formation of an electron-hole liquid in CdS by phase separation of optically excited carriers. Measurement of the electron-hole-liquid density as a function of pump intensity and sample temperature determines the liquid portion of the liquid-gas coexistence curve giving a low-temperature liquid density of 2×${10}^{18}$ ${\mathrm{cm}}^{-3\mathrm{}}$ and $T_c=55\mathrm{}°$K.

The properties of dilute Ruderman-Kittel-Kasuya-Yosida-coupled classical spins randomly embedded in an fee lattice have been investigated by computer simulation. Results at $T=0\mathrm{}$ are given for spatial correlations, molecular-field distributions, susceptibility, and frequencies of elementary excitations. Treating the latter as bosons, we find quantitative agreement with measured specific-heat values. The susceptibility $\chi \mathrm{}\left(0\right)\mathrm{}$ is also in accord with experiment.

We present a global stability analysis of possible states in narrow current-carrying superconductors below $T_c$ within time-dependent Ginzburg-Landau theory. A reversible superconducting-to-normal transition may take place at a current density $j_c$ lower than the maximum supercurrent $j_{max}$. Localized phase slip occurs spontaneously in a narrow range below $j_c$.

My high-resolution studies of the bound-exciton luminescence in Ga-doped Si reveal a triplet structure. Also, I report for the first time bound multiexciton complexes associated with Ga, which are similar to those previously reported for Si doped with P, Li, and and B. In the case of Ga, however, the $m=2\mathrm{}$ bound-multiexciton complex luminescence is found to be split by an amount equal to the splitting between two of the bound-exciton lines, strongly suggesting that the $m=2\mathrm{}$ complex decays into the bound exciton.

The Zakharov-Shabat theory of integrable systems with more than one spatial dimension breaks down when certain resonances between solitons occur. Remarkably, the resonance condition is precisely the same as that for the strong interaction of three weakly coupled linear dispersive waves. This provides a mechanism for the creation of new particles by collision.

In gauge theories with $V+A$ currents and new leptons, effects that do not separately conserve the $\mu$- and $e$-lepton numbers are dramatically larger than those predicted in the pure $V-A$ theories. The branching ratios for $\mu \to e\gamma$ and $K_L\to e\mu$ are found to be comparable to their present experimental limits.

The elastic-scattering angular distribution of 90-MeV ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ on ${}_{}{}^{184}{}_{}{}^{}\mathrm{W}$ exhibits a dramatic deviation from the typical Fresnel shape, which cannot be reproduced by standard optical-model calculations. The effect, a decrease in the elastic cross section below the Rutherford cross section even at forward angles, is due primarily to Coulomb excitation, and will be even more pronounced for heavier projectiles.

The quadrupole moment of the 8-μs fission isomer in ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$ has been determined with a newly developed charge-plunger technique for measuring lifetimes of states decaying by converted transitions. With a statistical accuracy of 7%, values between 34 and 39 b are obtained, depending on the unknown isomeric spin. The deformation of the second minimum described by the axis ratio of a spheroid is deduced to be $\frac{c}{a}=2.0\mathrm{}\pm 0.1$.

We have studied the time-resolved spectra, the energy-resolved spectra, and the total intensity of light emission induced by near-resonance two-photon excitation to the $4{}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}$ and $4{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ levels of Na over the detuning range $-7\mathrm{} {\mathrm{cm}}^{-1\mathrm{}}<~\Delta <~7 {\mathrm{cm}}^{-1\mathrm{}}$. The time-resolved spectra of Na perturbed by Ar exhibit a fast adiabatic component and a slow resonance-fluorescence component. The cross section for phase-shifting, $T_2$-type collisions in this atomic system is $\sigma =110\mathrm{}\pm 20$ ${\mathrm{\AA }}^2$.

A very-large-diameter (∼½m) uniform electron beam is injected along a magnetic field ($B_0\simeq 75$ G) into a dense background plasma ($n_e\simeq {10}^{10}$ ${\mathrm{cm}}^{-3\mathrm{}}$). The beam drives oblique whistler waves ($\omega <{\omega }_c<{\omega }_p$) unstable which are in resonance with the beam ($\frac{\omega }{k_{\parallel }}\simeq v_b$) and propagate nearly along the resonance cone angle ($cos\theta =\frac{k_{\parallel }}{k}\simeq \frac{\omega }{{\omega }_c}$). Growth of test waves as well as spontaneous broad-band emission reminiscent of very-low-frequency hiss are observed.

When a 1-MV, 315-kA, self-pinched electron beam is focused onto a thin-wall spherical target, the energy deposition per unit mass is 5 times larger than for a similar beam interacting with a thick target. Numerical modeling of the electron flow in the diode indicates that modification of electric and magnetic fields and electron trajectories by the target produces multiple passes through a thin target and an increase in beam electron density in the target. This produces the enhanced energy deposition in the target.

In the small-cold-beam limit, the beam-plasma instability is identical to the interaction in a traveling wave tube. We built a traveling wave tube to investigate the late-time development of this instability. We observe five trapped-particle oscillations following the saturation of a single launched wave. These oscillations can be destroyed either by increasing the wave damping or by modulating the main wave with unstable test waves.

We present measurements of the influence of magnetic fields on the flow stress of copper and show that the mobile dislocations are affected by magnetic fields. This observation is consistent with the mobile dislocations moving at high velocities, so that inertial effects must be considered when dislocations move in copper. We describe the effect by treating the dislocation according to a string model with the inclusion of a damping term due to electrons.

The dominant mechanism for spin conversion in solid C${\mathrm{H}}_4$ in the $\beta$ phase is found to be a hybrid process in which intramolecular dipolar interactions mix the nuclear spin states, and the intermolecular octupole interaction, modulated by phonon emission, causes transitions between orientational states. The conversion rate calculated for free rotor molecules is 31 to 54% per hour. The mechanism is shown to be inefficient for ordered molecules which are estimated to convert at least 1000 times slower.

${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ nuclear-quadrupole-resonance data show that the electric-field-gradient tensor at the ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ sites in terephthal-bis-butylaniline deviates from cylindrical symmetry in the biaxial smectic-$C$, smectic-$H$, and smectic-VI phases whereas it is cylindrically symmetrical in the uniaxial smectic-$A$ phase. The results suggest that in the smectic-$C$ phase the molecular tilt induces the rotational bias and not vice versa, whereas in the smectic-$H$ phase the situation is different and the results may be interpreted within the Meyer-McMillan model.

A calculation is presented of the total energy of metallic hydrogen for a family of face-centered tetragonal lattices carried out within the self-consistent phonon approximation. The energy of proton motion is large and proper inclusion of proton dynamics alters the structural dependence of the total energy, causing isotropic lattices to become favored. For the dynamic lattice the structural dependence of terms of third and higher order in the electron-proton interaction is greatly reduced from static lattice equivalents.

We find that the inclusion of the pseudo-three-body forces between all neighbors does not remove the difficulty of obtaining a consistent analysis of the microwave spectrum of solid hydrogen observed by Hardy and Berlinsky. We propose a novel anisotropic interaction, due to the deviation from axial symmetry of the pair distribution function of neighboring molecules, leading to a satisfactory interpretation, and yielding new information about lattice dynamics.

A new monoenergetic nanosecond pulsed source of high-energy phonons is described for doing time-resolved phonon spectroscopy. The phonons, internally generated by excited-state spin-lattice relaxation following optical excitation with a pulsed tunable dye laser, are monitored with nanosecond resolution from enhanced emission of the upper excited state due to resonant absorption. The technique is applied to the determination of the inelastic scattering time of 29-${\mathrm{cm}}^{-1\mathrm{}}$ phonons in ruby (${\tau }_p=530\mathrm{}$ ns).

Proton damage rates in Ag measured below 10 K show good agreement with calculated defect-production cross sections for low-energy recoils. A substantial decrease in damage efficiency (from $\overline{\xi }=1\mathrm{}$ to $\overline{\xi }\approx 0.6$) occurs as the energy and/or mass of the incident particle increases and displacement cascades are produced. Preliminary results are consistent with cascade efficiencies near $\xi =0.3\mathrm{}$ and an effective transition from $\xi =1\mathrm{}$ to $\xi =0.3\mathrm{}$ centered near recoil energies between 1 and 3 keV.

The electric quadrupole interactions produced by near-neighbor impurity atoms of Cu, Zn, In, Sn, and Au in a cubic Ag metal lattice are measured as a function of temperature by the time-differential perturbed angular correlation method. The obtained electric quadrupole frequencies $\omega$ can be reproduced by the relation $\omega \mathrm{}\left(T\right)=\omega \mathrm{}\left(0\right)(1-\alpha T^{\frac{3}{2}})$ with a strong dependence of the coefficient $\alpha$ on the impurity atom. The results are discussed in terms of recently proposed models to explain the $T^{\frac{3}{2}}$ dependence.