The $3S-5S$ transition of Na atoms is induced by absorption of two photons, one each from two circularly polarized beams traveling in opposite directions through the vapor. The beams are derived from a tunable, narrow-band pulsed dye laser. Doppler broadening is absent and the hyperfine structure is resolved. The hyperfine interaction constant $A_{5S}$ in the $5S$ state of the ${\mathrm{Na}}^{23}$ atom is determined to be 101±15 MHz.

Using coincidence techniques, we have measured the cross section for capture of electrons from the $K$ shell of argon atoms by protons in the energy range from 2.5 to 12 MeV. Of the total cross section for electron capture, the contribution of capture from the argon $K$ shell increases with proton energy from 0.5% at 2.5 MeV to 47% at 12 MeV. The contribution of electron capture to the total argon $K$-shell tonization cross section decreases from 0.4% at 2.5 MeV to less than 0.1% at 12 MeV.

Spin and antisymmetry have been incorporated into a hyperspherical expansion of the many-electron wave function. This new expansion increases the range of exact and approximate results available for atomic systems.

Propagation of electromagnetic waves in a large plasma reveals that refraction effects are much more significant than the amplitude swelling commonly predicted from the reduction in group velocity. Near electromagnetic wave cutoff, direct conversion into short-wavelength electron plasma waves is observed. Strong resonant enhancement of the electric field parallel to the density gradient is measured.

We report observations of an anomalous behavior in the Kapitza resistance between Cu or Pb and liquid helium II in the range 1-2 K. Systematic deviations from linearity at small heat fluxes have been observed for the temperature difference as a function of heat current. The dependence of the anomaly upon diameter and temperature is described, as well as possible origins of the effect.

Experiments have been conducted on an adiabatic toroidal compressor with tangential injection of two 14-15-keV, 3-4-A beams of ${\mathrm{H}}^0$ or ${\mathrm{D}}^0$. The ion-temperature rise for both ${\mathrm{H}}^{+}$ and ${\mathrm{D}}^{+}$ plasmas is 70-80 eV (i.e., 35-40%), consistent with theoretical expectations for charge-exchange-limited energy transport at neutral-atom densities ≅ ${10}^9$ ${\mathrm{cm}}^{-3\mathrm{}}$. The injected ions are found to decelerate in agreement with classical theory and produce an initial plasma ion heating rate of ∼ 20 keV/sec.

It is proposed that the large linear term in the low-temperature specific heat of dilute magnetic alloys is due to the magnetization of clusters of near-neighbor magnetic impurities, which can be weakly coupled to one another because of the existence of easy axes of magnetization produced by the anisotropic part of the near-neighbor exchange. The concentration independence of the linear term is shown to be consistent with this hypothesis.

Surface reflectance spectroscopy is used to determine optical transitions associated with the electronic structure of a W(100) surface during ${\mathrm{H}}_2$ chemisorption. Correlation with photoemission and field-emission data attributes these transitions to excitations from intrinsic and adsorbate-induced levels to final states at the Fermi energy.

The shape of soft x-ray absorption spectra extending 100 eV above the $L_{\mathrm{II},\mathrm{III}}$ x-ray threshold is calculated for Na, Al, and Si using a simple orthogonal plane-wave final state including backscattering from near neighbors, and hydrogenic-core wave functions. Comparison with synchrotron-radiation absorption and newly measured electron energy-loss spectra shows good agreement between the present simple calculation and experimental data.

Using a nonlocal pseudopotential, including spin-orbit interactions, we have calculated a band structure for GaAs which is in excellent agreement with electroreflectance, wave-length-modulation, and photoemission experimental results. As in a calculation by Pandey and Phillips, an order of magnitude in accuracy has been gained over existing band structures; the largest discrepancy with Schottky-barrier electroreflectance measurements is less than 0.08 eV. The $E_0^{\prime }$ conflict is resolved in favor of Aspnes's interpretation.

A new technique for determining spin sequences and mixing ratios has been used to investigate the ground state band of ${}_{}{}^{102}{}_{}{}^{}\mathrm{Pd}$. This new method is based on the observation of coincidences at only one angle rather than measuring a complete angular correlation. The results show that the unusual spin sequence previously proposed for the ground state band of ${}_{}{}^{102}{}_{}{}^{}\mathrm{Pd}$ is not correct.

The reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$)${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ has been studied at a bombarding energy of 100 MeV. The measured differential cross sections have been compared with exact finite-range distorted-wave Born approximation calculations including recoil. The angular distribution of the reaction populating the $2s_{\frac{1}{2}}$ state in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ at 3.09 MeV shows pronounced oscillations which are out of phase with those of the predicted angular distribution.

The reactions ${}_{}{}^6{}_{}{}^{}\mathrm{Li}\mathrm{}(p,pn)\mathrm{}{}_{}{}^5{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}\mathrm{}(p,pn)\mathrm{}{}_{}{}^8{}_{}{}^{}\mathrm{Be}$, and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}\mathrm{}(p,pn)\mathrm{}{}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, as well as the reaction ${}_{}{}^6{}_{}{}^{}\mathrm{Li}\mathrm{}(p,2p)\mathrm{}{}_{}{}^5{}_{}{}^{}\mathrm{He}$, have been studied at 46 MeV. The plane-wave impulse approximation (PWIA) has been used for a preliminary analysis. The ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ cross sections show a pronounced $p$-state minimum near zero recoil momentum as expected in the PWIA. No such minimum is seen for either reaction of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$. The angular dependence of the three ($p,pn$) reactions departs strongly from PWIA predictions.

Excitation functions of the fifteen most strongly populated states ($9<\mathrm{}{E}_x<17\mathrm{}$ MeV) in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},p){}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ have been studied using a magnetic spectrograph. A resonance structure was observed for transitions to several final states at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=19.3\mathrm{}$ MeV with ${\Gamma }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\cong 500$ keV. Two particle-bound states in ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ at 9.08 and 9.84 MeV are particularly strongly populated in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},p)$ at the resonant energy. The further study of the structure of these states may provide an important clue to the nature of the observed ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ resonance.

The effects of the deuteron $D$ state on sub-Coulomb $d,p$ reactions are explained in terms of a simple physical model. The model, which is based on a classical description of the reaction, makes it possible to understand the observed $D$-state effects for ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}(d,p){}_{}{}^{209}{}_{}{}^{}\mathrm{Pb}$ at 9 MeV.

Combining the low-energy theorem by Crewther and by Chanowitz and Ellis on the anomalous vertex function for partially conserved dilation current and a new result from the most conventional vector-meson dominance, we predict the asymptotic limit of the ratio $\frac{\sigma (e^{+}+e^{-}\to \mathrm{hadrons})}{\sigma (e^{+}+e^{-}\to {\mu }^{+}{\mu }^{-})}$ to be $R\cong \frac{16{\pi }^2}{f_0^{}{}_{}{}^2}=5.7\mathrm{}\pm 0.9$, which is in remarkable agreement with the preliminary data from the Cambridge Electron Accelerator $e^{+}-e^{-}$ colliding-beam experiment but in strong contradiction with the other predictions $R=\frac{2}{3}$ and $R=2\mathrm{}$ in the single- and three-triplet fractionally charged quark models.

Charge states of argon produced by bombardment with 100-keV to 1-MeV ${\mathrm{H}}^{+}$ and ${\mathrm{He}}^{+}$ projectiles were studied by examining high-resolution $L$ x-ray satellite spectra. Large differences appear in charge-state populations determined from x-ray data and Auger-electron data.

NMR signals from diatomic alkali molecules have been observed in optically pumped cesium and rubidium vapors. The nuclear relaxation times were found to be strongly dependent on the temperature and buffer-gas pressure. The relaxation time seems to be determined by at least two and possibly three major factors: motional narrowing of the molecular hyperfine structure, breakup of the diatomic molecules by collisions with buffer-gas atoms, and possibly chemical exchange of free atoms with atoms bound in the molecules.

The new wave-particle adiabatic interaction due to compressed flow is found by kinetic equations. Compressed flow means ${\overrightarrow{\mathrm{V}}}_E\ne 0$, where ${\overrightarrow{\mathrm{V}}}_E$ is the electric-field drift velocity. The adiabatic destabilization due to compressed flow is effective for the fast magnetosonic modes. These hydromagnetic drift instabilities would be important in the transition region where the Earthward motion of the tail plasma sheet is mostly retarded, as well as in laboratory adiabatic compression experiments.

Cylindrical solitons are seen to evolve from compressive cylindrical pulses in a collisionless plasma. The properties of these solitons are found to be consistent with the known properties of one- and three-dimensional solitons.