The density distribution of low-temperature spin-polarized atomic hydrogen in a realistic magnetic field profile is calculated for densities below and above the critical value for Bose-Einstein condensation. The distribution is an identifying characteristic. Magnetic compression and instability due to thermal leakage of the atoms is treated.

The dielectric function derived from polarized surface-reflectance-spectroscopy studies of the H/W(110) system is compared with that calculated for different hydrogen configurations. The orbital symmetry of the adsorbate states is identified and features of the surface band structure are characterized. It is found that the most likely adatom position is in a bridged site.

We present a linear-response formulation of Knight shifts in metals based on the density-functional theory. The approach emphasizes the importance of achieving self-consistency with respect to both the charge and spin densities and includes core polarization. An application to simple metals indicates that, in this case, the Knight shift is essentially a local property, independent of structure. Satisfactory agreement with experiment is achieved.

Results of ab initio self-consistent linear muffin-tin orbital energy-band studies for Eu${\mathrm{Mo}}_6$${\mathrm{S}}_8$, Gd${\mathrm{Mo}}_6$${\mathrm{S}}_8$, Sn${\mathrm{Mo}}_6$${\mathrm{S}}_8$, and Sn${\mathrm{Mo}}_6$${\mathrm{Se}}_8$ including all electrons in all 15 atoms/unit cell are reported. The large charge transfer from both the Eu, Gd, and Sn sites and from the Mo sites to the chalcogens is shown to be the driving mechanism with which to explain their unusual magnetic and superconducting properties.

Two successive phase separations can exist for an electron-hole system in a semiconductor having isoelectronic impurities within a certain density range: One is between bound excitons and a hole plasma with electrons pinned on the impurities, and the other one is between this hole plasma and the usual electron-hole plasma.

The origin of the enhancement of the near-surface yield of backscattered projectiles at angles close to 180° for swift light ions in solid targets is shown to be a correlation between outgoing and incoming paths which occurs when an ion scatters by almost 180° in one of its collisions in a solid. The theory does not invoke the crystal structure, or the disturbance of the medium by the ion. Calculations agree with experiment for 1-MeV ${\mathrm{He}}^{++}$ in Pt.

Shifts in the core-level binding energies of surface atoms relative to bulk atoms which show a dramatic dependency on surface crystallography have been observed. Surface-atom core-level emission intensities are shown to give direct information on the number of surface atoms, while binding energies give information on the surface-atom coordination number. These data show that the reconstructed Ir(100)-(5×1) face is described by a compressed hexagonal monolayer.

Proton magnetic resonance data are presented for a series of plasma-deposited $a$-Si: H films with hydrogen contents ranging from 32 to 8 at.%. Line-shape and line-width analysis leads to the conclusion that the spatial distribution of hydrogen is inhomogeneous in all samples.

The valence bands of pure graphite and several alkali graphite intercalation compounds were studied by ultraviolet photoelectron spectroscopy ($h\nu =21.2\mathrm{}$ eV). The most significant observation is an intensity peak at the Fermi energy $E_{\mathrm{F}}$ in the intercalation compounds. This peak is mainly due to alkalilike $s$ states. The density of states at $E_{\mathrm{F}}$ is enhanced by a factor of 30 compared with pure graphite. The alkalilike conduction bands in the first stage alkali graphite interclation compounds are similar to those of pure alkali metals.

A comparison of angle-resolved photoemission energy distributions for pure graphite and the intercalation compound Li${\mathrm{C}}_6$ show that considerable charge is transferred from Li to C, as expected; but the valence bands do not shift uniformly upon intercalation, in contradiction to the rigid-band approximation. Backfolded bands imposed by the two-dimensional Li superlattice are directly identified for the first time.

This Letter reports donor-acceptor pair spectra in CuCl crystals. A simple neutral-donor, neutral-acceptor complex does not explain the data. Recent calculations have predicted an ${\mathrm{O}}^{--}$ level near the conduction-band minimum. It is this level which is speculated to be the source of electrons for the highly conducting state of this potentially excitonic superconducting material. The photoluminescence results reported in this paper do not confirm the ${\mathrm{O}}^{--}$ level but would be consistent with its existence.

The total magnetic susceptibility of the conduction electrons is calculated for a simple metal containing a charge-density wave. A large (∼18%) anisotropy in the susceptibility is predicted for the charge-density wave model of potassium. In this case, the susceptibility is most paramagnetic when the magnetic field and charge-density wave vector, $\overrightarrow{Q}$, are parallel. The possibility of producing single-$\overrightarrow{Q}$ samples by cooling in a magnetic field is discussed.

Electron mobility measurements have been performed in subcritical and supercritical ammonia vapor in the density range from 6×${10}^{18}$ to 3×${10}^{21}$ molecules/${\mathrm{cm}}^3$ and in the temperature range of 210 to 440 K. In the density range from 2×${10}^{20}$ to about 3×${10}^{21}$ molecules/${\mathrm{cm}}^3$ an anomalous decrease of electron mobility by more than two powers of ten is observed with increasing vapor density, indicating a "transition" from the delocalized to the localized electron state.

It has been observed that the photoexcited $M_3{M}_{4,5}{M}_{4,5}\left({}_{}{}^1{}_{}{}^{}G\right)$ Auger line in Zn asymmetrically broadens to lower energy with increasing photon energy. The broadening can be described by a change in the asymmetry parameter $\Delta \alpha =0.09\mathrm{}$ in a Doniach-Sunjic line shape. This is the first evidence for the transition from the adiabatic to the sudden regime in a solid. The onset of this change ∼14 eV above threshold is related to $3d$ screening electron excitations which are seen as $3p$ core-level satellites.

We calculate the abundances of anomalous light, $Z>\mathrm{}1\mathrm{}$ nuclei that would be produced by primordial nucleosynthesis if there exist new neutral, stable baryons.

The specific heat, $C\left(T\right)\mathrm{}$, of the insulating spin-glass ${\mathrm{Eu}}_x{\mathrm{Sr}}_{1-x}\mathrm{S}$ with $x=0.40\mathrm{}$ exhibits a linear term $\gamma T$ and no singularity at $T_f$, like metallic spin-glasses. A new term, $\delta T^{-2\mathrm{}}$, is found which may arise from totally decoupled clusters created by frustration. The field dependence, $\gamma \mathrm{}\left(B\right)\mathrm{}$ and $\delta \mathrm{}\left(B\right)\mathrm{}$, show maxima. With $x=0.54\mathrm{}$ the behavior is similar. $C(T, B)$ and $\chi (T, B)$ there indicate the spin-glass phase to be supressed at $B=1\mathrm{}$ T.

The charge-imbalance voltage induced in a clean superconductor by a supercurrent density ${\overrightarrow{J}}_s$ in the presence of a temperature gradient $\nabla T$ is shown to be $V=\frac{2\pi v_{\mathrm{F}}l{\lambda }^2\Delta \left({\overrightarrow{J}}_s·\nabla T\right)}{3c^2{k}_{\mathrm{B}}{T}^2{cosh}^2\left(\frac{\Delta }{2k_{\mathrm{B}}T}\right)g_{\mathrm{NS}}\mathrm{}(1-Z)\mathrm{}}$, where $v_{\mathrm{F}}$, $l$, and $\lambda \mathrm{}\left(T\right)\mathrm{}$ are the Fermi velocity, mean free path, and penetration depth, $g_{\mathrm{NS}}$ is the normalized tunnel conductance of the probe junction, and $Z\left(\frac{\Delta }{T}\right)$ is a known function. This result agrees well with the experiments of Clarke, Fjordbøge, and Lindelof.

The transport of electrons or excitations on a lattice randomly occupied by guests is considered. The equation governing the transport in any configuration is assumed to be the master equation. A projection operator technique is used to derive the exact equation governing the transport averaged over all configurations, which can be written as either a generalized master equation or the continuous-time random-walk equations (CTRW), establishing the correctness of the CTRW for these problems.

Properties of $\eta \mathrm{}\left(549\right)\mathrm{}$ and ${\eta }^{\prime }\mathrm{}\left(958\right)\mathrm{}$ are used to measure the quark charges. The result strongly favors fractional charges.

$\frac{d^2\sigma }{d\Omega \mathrm{dT}}$ for ${\pi }^{+}$ mesons produced in ${\pi }^{-}p\to {\pi }^{-}{\pi }^{+}n$ was measured at seven incident energies between 203 and 357 MeV and the integrated reaction cross section was calculated. The matrix element, when extrapolated to threshold and compared with soft-pion calculations, determined the chiral-symmetry-breaking parameter $\xi =0.05\mathrm{}\pm 0.26$, which is consistent with the Weinberg Lagrangian. The large hard-pion contributions at 203 MeV demonstrated the absolute necessity for comparing at threshold.