Cross sections for electron capture by fully stripped ions of beryllium, boron, carbon, nitrogen, and oxygen from ground-state atomic hydrogen have been calculated by applying the previously reported generalized formulation in the continuum intermediate-state approximation. The calculated results are compared with the existing available experimental and theoretical results.

Transition energies and rates in the $L_1-L_{23}{M}_1$ Coster-Kronig spectrum of argon have been calculated in the intermediate-coupling scheme. Strong mixing of the final ionic states ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$, caused by the spinorbit interaction, virtually removes the large discrepancy between previously calculated relative term intensities and experimental data. Transition energies also agree well.

Fluctuations of the lattice spacing in a "blue" phase are seen with use of reflection microscopy. The observability of these fluctuations implies a shear modulus for the blue phase which is much less than any theoretical estimate for the "bulk modulus" (energy cost to change the lattice spacing without actually compressing the fluid). These fluctuations resemble nematic "twinkling" under the microscope. Possible reasons for this similarity are discussed.

Random walks on the Vicsek fractals (models of diffusion-limited aggregates) are studied with the results $\frac{{2d}_F}{d_W}=1.188, 1.333, 1.441, \dots$ for $d=2, 3, 4, \dots$. These results are compared to the numerical work of Meakin and Stanley and with the Alexander-Orbach conjecture. The relationship of the Alexander-Orbach conjecture to the Einstein relation is discussed.

The statistical theory of nonequilibrium thermodynamics is used to obtain expressions for the reversible heat and work at nonequilibrium steady states. The variable which is thermodynamically conjugate to the generalized entropy is an integrating factor for the reversible heat.

A solution to the classical anharmonic-oscillator equation of motion $\ddot{x}=-x-\lambda x^{2n-1}$ is obtained by rescaling the perturbation series. The resulting series involves a coupling constant that remains finite for $\lambda \gg 1$ and thus converges rapidly for all $\lambda$.

A method for avoiding numerical linear dependence in the solution of the coupled-channel differential equations arising from the single-center expansion applied to the quantum mechanics of atoms and molecules is presented. The method is extended to allow the calculation of the Green's function with a noncentral potential.

The $T$-matrix element for resonant electron capture in ${\mathrm{H}}^{+}$ + $\mathrm{H}\mathrm{}\left(1s\right)\mathrm{}$ collisions at high velocities is studied into the continuum-distorted-wave approximation. Comparisons are given with recently reported [Phys. Rev. A 26, 1109 (1982)] second-order-Born-approximation calculations of McGuire et al; to analyze the influence of higher orders on Re $T$ and Im $T$. Structures overlapping the double-scattering angular region (which appear as a dip in the differential cross sections) are shown as coming from contributions of large-impact-parameter encounters.

We comment on the suitability of field ionization and x-ray observation for the investigation of Rydberg states in ion-atom collisions and clarify apparent discrepancies which have been recently communicated.

We comment on some statements and results in a paper by Hogg and Huberman [Phys. Rev. A 29 275 (1984)] on two coupled logistic systems and present numerical values for the first and second Lyapunov characteristic exponents of their model.

Recent precision $K\alpha$,$K\beta$ x-ray-emission energy measurements at the National Bureau of Standards [Kessler et al., Phys. Rev. A 26, 2696 (1982)] are analyzed in a quantitative way in terms of the ground-state correlation energy and the dynamical relaxation energy shift. The dynamical relaxation energy shift of $M_{23}$ levels of a number of elements from $42<~Z<~97$ are obtained approximately.

Negative ions are observed in a rubidium vapor when atoms are excited to the $6d$ level. Analysis shows that they correspond to the collision $\mathrm{Rb}\left(6d{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}\right)+\mathrm{Rb}\mathrm{}\left(5s\right)+\Delta E\to {\mathrm{Rb}}^{+}+{\mathrm{Rb}}^{-}$. The rate coefficient of the process is found to be (1.1±0.6)×${10}^{-12\mathrm{}}$ ${\mathrm{cm}}^3$ ${\mathrm{s}}^{-1\mathrm{}}$ and the corresponding cross section 1.3×${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$.

Total, as well as partial, electron-transfer cross sections in ${\mathrm{H}}^{+}$ + Na and ${\mathrm{H}}^{+}$ + K collisions have been calculated in the impact-energy region 0.2-20 keV. The calculations are based on the atomic-orbital expansion method. Resulting total-transfer cross sections are in good agreement with experimental data by Grüebler, Schmelzbach, König, and Marmier, and $2s$ partial-transfer cross sections agree with recent measurements by Berkowitz and Zorn, though in the case of ${\mathrm{H}}^{+}$ + Na collisions only up to a normalization factor. Possible reasons for discrepancies with results from other (mutually disagreeing) theoretical studies are discussed.

An ultrafast coherent Raman spectroscopy with tunable excitation is presented. It is applied to the analysis of vibrational spectra of hydrogen-bonded aggregates of pyridine and methanol. Whereas the spontaneous Raman spectrum exhibits a broad and featureless band, the line-narrowed spectra reveal three distinct lines. The concentration dependence of these lines suggests an assignment to well-defined aggregates of different sizes.

The diamagnetic shifts of the $m_J=0\mathrm{}$ and $m_J=\pm 1$ components of $6snp {}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ ($n=40,55,70,85,100\mathrm{}$) and $6s55p {}_{}{}^3{}_{}{}^{}P_{0, 1}^{}{}_{}{}^{}$ Rydberg states of ${}_{}{}^{172,174}{}_{}{}^{}\mathrm{Yb}$ have been measured in external magnetic fields up to ≌3 kG by high-resolution three-photon spectroscopy. The diamagnetic shifts have been analyzed to yield the singlettriplet mixing due to spin-orbit interaction. At $n=40\mathrm{}$, the singlet-triplet mixing derived from diamagnetic shifts and hyperfine-structure data are in excellent agreement.

A large anisotropy in the absorption of light has been detected in a sheared mixture of nitrobenzene and $n$-hexane at critical concentration. This dichroism is well supported by the Onuki and Kawasaki theory. The corresponding birefringence amplitude exhibits some discrepancy when compared with the above theory, but this vanishes if the same scaling function as for dichroism is used.

We report a summary of universal exponents and fractal dimensions associated with Feigenbaum attractors, and an efficient method for computing these fractal dimensions.

The onset of magnetohydrodynamic convection in the presence of temperature modulation in Rayleigh-Benard geometry is studied in perturbation theory. In a certain parameter range the magnetic field and the temperature modulation are shown to produce a null effect.

A bifurcation diagram is given for an extremely simple nonautonomous circuit. It is a series connection of a linear resistor, a linear inductor, and a two-segment, piecewise-linear capacitor driven by a sinusoidal voltage source. The diagram resembles, in a surprisingly close manner, experimentally observed ones and numerical results with much more complicated models. A cross section of the chaotic attractor is also given.