The strength, line shapes, polarization selection rules, and magnetic field behavior of two-magnon light scattering in antiferromagnetic Mn${\mathrm{F}}_2$ are reported, and they are interpreted in terms of an excited-state exchange coupling between sublattices and the magnon dispersion relation

First-order Raman effect has been induced in the cubic perovskite, KTa${\mathrm{O}}_3$, by application of an external electric field. The normally infrared-active "ferroelectric" mode has thus been studied by Raman scattering at temperatures between 8 and 300°K.

The partial muon-capture rates in ${\mathrm{O}}^{16}$ leading to low-lying states in ${\mathrm{N}}^{16}$ are calculated in Migdal's theory of nuclear structure, with results that agree well with the available experiments for suitable values of $C_P=\frac{m_{\mu }{F}_P}{F_A}$. It is thus argued that the neglect of $G$-parity irregular terms was not the cause of previous apparent disagreement. The capture rates are in turn employed to examine the effect of the velocity-dependent terms in Migdal's effective amplitude.

The electromagnetic renormalization of the $\Delta S=0\mathrm{}$ weak vector coupling constant $G_V$ coming from the corrections to the vector part of the weak Hamiltonian is a universal divergent constant, independent of the details of the strong interactions.

Electrons photoexcited in $p^{++}$-GaAs (with Cs surface monolayer) are found to "thermalize" in either the $\Gamma$ or $X$ conduction-band minima while diffusing to the surface. Two strong peaks separated by 0.3 eV of photoemitted electrons associated with these minima are observed in the energy distribution curves for $1.5 \mathrm{eV}<~h\nu <~3.2 \mathrm{eV}$.

Comparison of experimental results for cyclotron-resonance measurements above and below the Reststrahl frequency reveals anomalies attributable to polarons.

Amplitude-dependent ultrasonic attenuation has been observed for shear waves (10-60 MHz) propagating in the [100] direction of a 99.999%-pure copper single crystal in the temperature range 4.2 to 300°K. The amplitude dependence was found to be consistent with breakaway of dislocations from pinning centers, but no experimental evidence of an electron viscosity damping of dislocations was seen at 4.2°K for frequencies up to 60 MHz.

The Slater model of the two-dimensional potassium dihydrogen phosphate crystal is solved exactly under the additional assumption that the dipoles are excluded from pointing along one direction of the crystal axis. The Curie temperature $T_c$ is not affected by this additional assumption but the phase change becomes a second-order transition. Complete polarization occurs below $T_c$ with specific heat $\sim {(T-T_c)}^{-\frac{1}{2}}$ near and above the Curie point.