Below 160 K, crystalline ${\mathrm{Na}}_2$[Fe${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_5$NO] · 2${\mathrm{H}}_2$O is transformed into an extremely longliving metastable state ($\tau >{10}^7$ sec) by irradiation with 400-540-nm light. At $T>\mathrm{}160\mathrm{}$ K and by irradiation with red light the new state decays exponentially. During population the transmission of the crystal shows characteristic time behavior with wavelength-dependent saturation. Raman spectra show the coexistence of the ground and metastable states. New infrared and visible absorption bands are interpreted in terms of an energy scheme of the metastable state.

We report the first measurement of the gas-to-solid phase transition of hydrogen occluded in amorphous silicon. The transition is very broad and occurs around 30 K confirming the nonuniform and highly compressed nature of hydrogen. The infrared-absorption spectra of the solid phase show that the ${\mathrm{H}}_2$ structure is strained with considerable interaction between the ${\mathrm{H}}_2$ and the Si walls of the microvoids.

A nonperturbative procedure for testing for the presence of proper axial anomalies is introduced for lattice gauge theories. We prove, in particular, that the nonlocal theory of Drell, Weinstein, and Yankielowicz produces a vanishing axial anomaly.

Chiral anomaly in (2+1)-dimensional fermion theory coupled with an external electromagnetic field is studied. Its connection with the quantized Hall effect is pointed out. Hall conductivity is quantized and agrees with the experimental value.

A $D$-state component in the $\alpha$ particle has been extracted from angular distributions of tensor analyzing powers for ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}(d,{\alpha }_0){}_{}{}^{87}{}_{}{}^{}\mathrm{Sr}$ at 9, 12, and 16 MeV. Exact finite-range distorted-wave Born-appproximation analyses including the effects of $L$ and $J$ mixing have been performed. The $D$-state parameter $D_2$, closely related to the asymptotic $D$- to $S$-state ratio for $d-d$ relative motion in the $\alpha$ particle, requires a value of $D_2=-0.3\mathrm{}\pm 0.1$ ${\mathrm{fm}}^2$ in order to fit the tensor analyzing power data.

To resolve the reported anomalous behavior of the $\alpha$-decay rates of ${}_{}{}^{186,188,190,192}{}_{}{}^{}\mathrm{Pb}$ we determined more accurate $\alpha$-decay branches for these isotopes. Our data result in $\alpha$-decay reduced widths whose dependence on $N$ is similar to that observed for other elements. However, contrary to the expectation of a shell effect at $Z=82\mathrm{}$, this new information indicates lead nuclei to be less hindered toward $\alpha$ decay than mercury isotopes. It appears that midway between $N=82\mathrm{}$ and $N=126\mathrm{}$ the proton number of 82 is not magic.

The inelastic electron-scattering cross sections of H, He, Be, C, and O were measured for 730-MeV electrons scattered at 37.1° for energy transfers to the nucleus up to 550 MeV. The nuclear response in the delta region is found to be quite similar for the $A>\mathrm{}1\mathrm{}$ targets. Although the differential cross section per nucleon at the peak of the delta region (380 MeV) is suppressed compared to that of the free nucleon, the area in the 230-550-MeV region is enhanced for the $A>\mathrm{}1\mathrm{}$ targets.

The circular polarization $P_{\gamma }$ of deexcitation $\gamma$ rays has been measured in coincidence with fast charged particles from reactions induced by light heavy ions at $\frac{E}{A}\approx 8$ MeV. Polarizations of up to $\left|P_{\gamma }\right|\approx 0.3$ were observed. The variations of $P_{\gamma }$ in sign and magnitude with the particle type, energy, and angle, and with the target mass reveal the effects of the particle-target interaction during a tangential passage along the target nucleus.

The most probable value for the total kinetic energy of reaction products from strongly damped collisions of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ was found to increase with bombarding energy only up to a limiting value. This behavior suggests that the orbital angular momentum of the dinuclear complex formed in these collisions has reached a saturation value beyond which further increase is not possible.

The formation of ${\mathrm{O}}^{-}$ and ${\mathrm{C}}^{-}$ ions via dissociative attachment in electron scattering from ${\mathrm{O}}_2$ and CO condensed on a polycrystalline platinum surface is reported. Below 15-eV impact energy, ${\mathrm{O}}^{-}$ from ${\mathrm{O}}_2$ arises essentially from the repulsive ${}_{}{}^2{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ state of ${\mathrm{O}}_2^{-}$, whereas in CO, ${\mathrm{C}}^{-}$ and ${\mathrm{O}}^{-}$ appear to be emitted from higher-energy repulsive states of C${\mathrm{O}}^{-}$ with yields much different from those found for the isolated molecule.

A time- and position-sensitive detector has been used for the first determination of the momentum distribution of correlated photofragments. A fast beam of ${\mathrm{H}}_2$ $c{}_{}{}^3{}_{}{}^{}\Pi _{\mathrm{u}}^{-}{}_{}{}^{}$ is observed to undergo three types of photodissociation: (1) radiative dissociation of individual rovibrational levels; (2) predissociation by barrier tunneling of quasibound levels, for the first time observed in a neutral system with fragment energy analysis; and (3) direct photodissociation, which has been rotationally resolved for the first time.

The electrons of $E_e^{\mathrm{c}.\mathrm{m}.\mathrm{}}=150-800\mathrm{}$ keV emitted during heavy-ion collisions were studied for the system Au on U at a beam energy of 3.9 MeV/u. The impact-parameter dependence is presented for the total electrons and for electrons from $1s_{\frac{1}{2}}\sigma$ and $2p_{\frac{1}{2}}\sigma$ states. The results are interpreted in terms of the strong relativistic enhancement of the electron density of the innermost quasiatomic shells with decreasing internuclear distance of the united atom system.

By use of a hydrocode it is shown that the interaction of high-intensity light with an expanding plasma surface produces a positive plasma cloud followed by a negative plasma cloud. This result, which is opposite to that without the laser light, is the result of the non-linear (ponderomotive) force.

A scaling theory is developed for aggregation by means of kinetic clustering of clusters. A global picture of static and dynamic critical properties emerges, whereby the dynamic critical exponent can be related to the fractal dimension. Furthermore, the growth process is described in terms of a purely kinetic model. The scaling predictions agree well with numerical results.

We study the dynamics of diffusion-limited cluster-cluster aggregation of aqueous colloids using quasielastic light scattering. Scaling behavior is found for the dependence of the mean cluster size on both time and initial concentration, and limits are placed on the scaling exponents of the cluster mass distribution. The fractal nature of the resultant clusters directly affects the exponents, illustrating the inherent relationship between the dynamic and static properties of kinetic aggregation processes.

Dynamic equation-of-state data are presented for liquid ${\mathrm{N}}_2$ single- and double-shocked to pressures of 100 GPa (1 Mbar), compressions to fourfold over initial liquid density, and internal energies to 1 MJ/mole. Three double-shock points lie above the principal Hugoniot in pressure-volume space, the first such observation in condensed matter. The data are interpreted in terms of a continuous phase transition, identified as molecular dissociation by comparison of the shock compression curves of liquid ${\mathrm{N}}_2$ and isoelectronic CO.

We have investigated the kinetics of the NaCl-to-CsCl phase transformation in RbI at room temperature ($P_c\approx 3.5$ kbar) by monitoring the time-dependent changes in neutron powder diffraction peaks. Above $P_c$ the rate of growth of the stable phase increases with increasing pressure, but the growth curves display a universal shape, consistent with the Kolmogorov model of nucleation and growth, when plotted versus a scaled time parameter $\tau =\frac{t}{{\tau }_0}\mathrm{}\left(P\right)\mathrm{}$.

We report the first measurements of the transition to superfluid turbulence in flows where the normal and superfluid velocities can be varied independently. The data reveal the existence of a critical line in the ($V_n$, $V_s$) plane. A simple model of a temperature-independent critical line gives reasonable agreement with the critical velocities measured in pure superflow, in two-fluid flow, and in thermal counterflow. Our results support the theoretical view that the critical velocity is dominated by boundary dynamics.

The origin of the two-peak photoemission and inverse-photoemission spectra in Ce and its pnictide compounds (CeP, CeSb, and CeN) is investigated with ab initio total-energy self-consistent supercell energy-band and molecular-cluster approaches to represent physically the competing mechanisms involved in $d$ or $f$ electron screening (antiscreening in the case of inverse photoemission) of the local $4f$ electron excitations. Good agreement with experiment is obtained in all cases including the "anomalous" case of CeN.

We have found that ${\mathrm{K}}_{0.3}$Mo${\mathrm{O}}_3$ acts as a current source on heating after the charge-density wave has been frozen into a metastable state by cooling to 4.2 K in the presence of small electric fields. The current emitted is dependent on the magnitude of the field applied on cooling, reflecting differences in the frozen-in metastable states. The relaxation of the charge-density wave from its metastable state is thermally activated and occurs with a distribution of relaxation times.