Laser-fluorescence spectroscopy has been applied to measure the spectrum of electric wave fields with high temporal resolution in a pulsed hollow-cathode discharge. A low-frequency and a high-frequency component can be identified.

A definitive determination of angle-resolved photon-stimulated desorption of ions from a well-characterized adsorbate, and a direct comparison with electron-stimulated desorption are reported. Ion angular distributions, energy distributions, and photon excitation spectra for ${\mathrm{O}}^{+}$ desorption from W(111) have been measured for oxygen coverages ranging from a fractional monolayer to a multilayer oxide.

The effect of surface roughening on the onset of vortex motion in thermal counterflow in a rotating channel has been investigated. Smooth surfaced channels exhibit a critical counterflow velocity independent of surface characteristics. Rough surfaced channels exhibit a larger critical velocity, larger by just the amount necessary to bring the average vorticity at the surface parallel to the surface.

${}_{}{}^{77}{}_{}{}^{}\mathrm{Se}$ NMR is used to study a proposal made by McMillan regarding the charge-density wave (CDW) in $2H$-Ta${\mathrm{Se}}_2$. The dependence of the NMR line shape is compared with predictions based on McMillan's theory. McMillan's hypothesis of "discommensurations" is confirmed—that the so-called incommensurate CDW is best described by commensurate regions separated by regions of phase slip.

The first direct measurement is reported of the bulk density of deep states in $n$-type $a$-Si: H. The spectral distribution is considerably different from previous field-effect and $C-V$ measurements and the overall density is much lower than has previously been reported. The states seen in these samples appear to be extrinsic and suggest that the extrapolated total density of deep states in pure $a$-Si: H may be less than ${10}^{15}$ ${\mathrm{cm}}^{-3\mathrm{}}$.

The infrared absorption from molecular monolayers is enhanced a factor of 20 by thin metal overlayers or underlayers with use of the attenuated-total-reflection technique. The total enhancement, including contributions from the attenuated-total-reflection geometry, is almost ${10}^4$. This effect is consistent with an electric field enhancement due to collective electron resonances associated with the island nature of the thin metal films.

In this Letter, a theoretical discussion of resonant photoemission in barium and cerium is presented. Calculations are performed using a time-dependent density-functional technique which both is accurate and provides a simple physical interpretation of the resonant phenomena.

(112) planes of W-amorphous-EuS field emitters exhibit a memory effect in the current-voltage characteristics, the actually drawn current being "locked in." In contrast to Ovshinsky-type memory switches, self-stabilization of the electron current occurs due to negative space charge. Measurements of the electron-spin polarization exclude a thermally induced mechanism. To our knowledge these memory structures are the smallest in solid-state physics.

A simple model is constructed for tunneling two-level systems interacting with conduction electrons in metallic glasses. The coupling constants do not commute in momentum space. Scaling theory shows a strong similarity with the antiferromagnetic Kondo effect, and it is shown that at low temperature a bound state is formed in which the motion of the tunneling atom and the angular dependence of the screening electron cloud verying in time are strongly correlated.

Chromodynamics with $n$ flavors of massless quarks is invariant under chiral $\mathrm{U}\mathrm{}\left(n\right)\mathrm{}\otimes \mathrm{U}\mathrm{}\left(n\right)\mathrm{}$. It is shown that in the limit of a large number of colors, under reasonable assumptions, this symmetry group must spontaneously break down to diagonal $\mathrm{U}\mathrm{}\left(n\right)\mathrm{}$.

The string constant (or, equivalently, the asymptotic Regge slope ${\alpha }^{\prime }$) is related to the $\Lambda$ parameter in quantum chromodynamics (QCD). The empirical information from the $\Psi$, $\Upsilon$ spectroscopies is used to determine this relation. In so doing a quarkonium potential in excellent agreement with experimental data is also obtained. It is found that ${\Lambda }_{\overline{\mathrm{ms}}}=0.5\mathrm{}$ GeV and ${\alpha }^{\prime }=1\mathrm{}$ ${\mathrm{GeV}}^{-2\mathrm{}}$.

Transverse form factors have been extracted for the low-lying neutron hole (particle) states of ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ from inelastic-electron-scattering data. A systematic, multipolarity-and momentum-transfer-independent quenching of ∼55% in the transverse amplitude is observed when compared with single-particle predictions for both electric and magnetic transitions. The magnitude of the observed effect is not readily explained by our present theoretical understanding of this nucleus.

Cross sections for simultaneous photoionization of He and excitation to ${\mathrm{He}}^{+}$ ($n=2\mathrm{}$) have been measured from threshold to 160 eV. The data show clear evidence of autoionization from levels converging on ${\mathrm{He}}^{+}$ ($n=3\mathrm{}$). Away from such structure, they are in good agreement with previous experimental values. None of the theoretical predictions gives the correct magnitude at low energies.

Resonantly enhanced multiphoton ionization signals through the $6s\left[\frac{3}{2}\right]J=1\mathrm{}$ state of Xe rapidly disappear at pressures above 0.30 Torr; concurrently, intense, vacuum-ultra-violet third-harmonic radiation is detected in the forward direction. Laser excitation spectra of the vacuum ultraviolet light exhibit increasing blue shifts and bandwidths with increasing pressure. The observed competition between ionization and third-harmonic generation is discussed in terms of a model involving fast collective emission.

An unambiguous experimental observation of current generation by unidirectional lower hybrid waves in a toroidal plasma is reported. Up to 10 A of current was driven by 500 W of rf power at 160 MHz.

The megaelectronvolt ion-channeling technique has been applied to the study of the Ni-Si interface. The Ni-Si interface, prepared under UHV conditions at ambient temperature, shows an interfacial region containing ∼1×${10}^{16}$ atoms/${\mathrm{cm}}^2$ of nonregistered Si. A measurement of the temperature dependence of the interfacial reactivity emphasizes the kinetic nature of the Ni-Si interface and the importance of Schottky-barrier height measurements at low temperatures for meaningful comparison with abrupt metal-semicon-ductor interface models.

A "nonequilibrium Hamiltonian" that describes adiabatic deformation has recently been used to obtain the bulk and shear viscosities of simple fluids. This Hamiltonian is used to derive equilibrium fluctuation experessions for the nonequilibrium distribution functions, studying in detail the most important of these, the pair distribution function for simple fluids in the linear-response regime.

Strain-induced splittings of the infrared-active TO phonon in Ca${\mathrm{F}}_2$, Sr${\mathrm{F}}_2$, and Ba${\mathrm{F}}_2$ are calculated from a least-squares fit of photoelastic dispersion data by an undamped oscillator model. The strain-induced oscillator-strength anisotropy appears negligible; the Szigeti effective charge remains a scalar. The shear deformation potential for [100] strain is ∼170 ${\mathrm{cm}}^{-1\mathrm{}}$ in all the materials; for [111] strain it is -82 ${\mathrm{cm}}^{-1\mathrm{}}$ for Ca${\mathrm{F}}_2$, -54 ${\mathrm{cm}}^{-1\mathrm{}}$ for Sr${\mathrm{F}}_2$, and -50 ${\mathrm{cm}}^{-1\mathrm{}}$ for Ba${\mathrm{F}}_2$.

${}_{}{}^{133}{}_{}{}^{}\mathrm{Cs}$ NMR results are reported for liquid Cs-Au alloys ranging from pure Cs to 18% excess Au in the ionic liquid compound CsAu. As one approaches CsAu from the Cs-rich side, a rapid drop in the Knight shift is observed, accompanied by a sharp peak in the nuclear relaxation rate at about 5% excess Cs in CsAu. Analysis of the static and dynamic hyperfine fields shows that the conduction electrons abruptly localize, probably as $F$- center analogs, when the concentration of excess Cs falls below about 7%.

Exceptionally large increases in the magnetic susceptibility (indicating nearly magnetic ordering) of thin films of Pd sandwiched between thicker Au films have been observed at low temperatures—presumably due to the expansion of the Pd average lattice constant by the Au. The large resultant Stoner factors and the modified paramagnon model of Levin and Valls indicate the possibility of observing $p$-wave superconductivity in Pd structures with reduced proximity effects.