A study of the velocity autocorrelation function for hard spheres over the entire fluid density region shows that deviations from exponential behavior are small. At very low density a small positive deviation is found which is accounted for in the Boltzmann theory of the self-diffusion coefficient. At higher densities the principal non-Markovian process is identified with a surprisingly long persistence of velocity currents. At still higher densities, near solidification, anticorrelating backscattering events predominate.

The electron-spin-resonance $g$ factor for a spin-½ impurity in a dilute alloy is predicted to be logarithmically divergent at low temperatures.

Nuclear-magnetic-resonance studies on dilute alloys of Fe in Cu metal give evidence for the existence of a singlet ground state for the magnetic impurity problem. The moment on the impurity is found to increase linearly with magnetic field but is independent of temperature in the region $\mathrm{kT}\ll {\mu }_{\mathrm{B}}H\ll k{T}_{\mathrm{K}}$.

Zero-field level-crossing effects have been optically detected in the nitric oxide molecule by observing the change in intensity of molecular fluorescence from a specified state with magnetic field. The intensity follows an inverted Lorentzian with a field strength at half-maximum of 0.379±0.030 G. Together with the radiative lifetime as recently determined by Jeunehomme, this gives for the molecular $g$ factor for this level a value of 0.762±0.060. This places an upper limit on the magnitude of $\gamma$, the molecular $\rho$-type doubling constant, of $\left|\gamma \right|<~1.3\times {10}^{-5\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ (390 KHz).

Experimental results are presented which show that carriers can be produced by photoionization of excitons in anthracene and it is pointed out that experimental results previously interpreted as evidence for exciton-exciton annihilation can more reasonably be interpreted in terms of exciton photoionization.

Electronic $K{\alpha }_1$ x-ray isotope shifts have been measured for ${\mathrm{Sn}}^{116-124}$, ${\mathrm{Sm}}^{148-154}$, ${\mathrm{W}}^{182-184}$, ${\mathrm{W}}^{184-186}$, and ${\mathrm{W}}^{182-186}$ using a curved-crystal Cauchois spectrometer. The analysis of the measurements has included the volume effect, screening, normal and specific mass shifts, nuclear polarization, and electron magnetic moment interaction.

The chemical shift of the Sn $K{\alpha }_1$ x ray has been measured in the pairs Sn-SnO, SnO-Sn${\mathrm{O}}_2$, and Sn-Sn${\mathrm{O}}_2$ using a curved-crystal Cauchois spectrometer. Comparison of the observed shifts with the Mössbauer isomer shifts brings out the essential role played by the $5p$ electron density in the chemical shifts.

Precise measurements of the isotope shift for muonic $K$ transitions are reported for ${\mathrm{Si}}^{28,29,30}$, ${\mathrm{K}}^{40,41}$, ${\mathrm{Ca}}^{40,42,44,48}$, ${\mathrm{Fe}}^{54,56,57}$, ${\mathrm{Ni}}^{58,60,61,62}$, ${\mathrm{Cu}}^{63,65}$, ${\mathrm{Sr}}^{86,87,88}$, ${\mathrm{Zr}}^{90,92}$, and ${\mathrm{Sn}}^{116,117,118,119,120,122}$. The shifts ${\mathrm{Ca}}^{40}$-${\mathrm{Ca}}^{44}$ and ${\mathrm{Ca}}^{40}$-${\mathrm{Ca}}^{48}$ are of special interest, as they confirm the conclusions from electron scattering. The shifts ${\mathrm{Sr}}^{86}$-${\mathrm{Sr}}^{87}$ and ${\mathrm{Sr}}^{86}$-${\mathrm{Sr}}^{88}$ are found to be negative, indicating that the heavier isotope has a smaller charge radius.

Azimuthal asymmetries produced in $d-\alpha$ double scattering have been measured at ten second-scattering angles. Both scatterings take place at the same center-of-mass energy. Published sets of phase shifts are inconsistent with the present measurements. It has been demonstrated that $\alpha -d$ scatterings can be used to produce a deuteron beam with useful vector polarization at energies near 10 MeV.

A new method of calculating phase shifts for a Bethe-Salpeter equation is presented. The scattering amplitude is calculated below elastic threshold using the differential equation and variational methods, and then continued to the elastic-scattering region to find phase shifts.