Dynamics of a surface phase transition as monitored by in situ second harmonic generation

The dynamics of the (2 x 2)-3CO <--> dilute phase transition involving CO adsorbed on Pt(111) microfacets has been monitored in situ in a CO-saturated acidic electrolyte using potential step-second harmonic generation techniques. Apparent time constants derived strictly from the optical data were found to be orders of magnitude slower for the forward process as compared to those of the reverse process. This behavior is consistent with the activated nature of CO electrooxidation, which requires the presence of a neighboring adsorbed oxygenated species, for example, hydroxyl, for the process to ensue.     

Effect of radiative cooling on collapsing charged grains

The effect of the radiative cooling of electrons on the gravitational collapse of cold dust grains with fluctuating electric charge is investigated. We find that the radiative cooling as well as the charge fluctuations, both, enhance the growth rate of the Jeans instability. However, the Jeans length, which is zero for cold grains and nonradiative plasma, becomes finite in the presence of radiative cooling of electrons and is further enhanced due to charge fluctuations of grains resulting in an increased threshold of the spatial scale for the Jeans instability.     

Intermediate coupling model description of55Fe and57Fe

The properties of the negative parity states of⁵⁵Fe and⁵⁷Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states.     

Automatic Structure Determination of Organic Molecules： Principle and Implementation of the LSD Program

The LSD (Logic for Structure Determination) program gener-ates organic molecular structures from 1D and 2D NMR data without resorting to chemical shift databases. Its use in the res-olution of natural product structure determination problems has been already reported in the literature. This paper describes how data and structures are internally represented and pro-cessed by LSD to build solution structures.     

Dielectric losses of alkaline earth doped KCl and NaCl crystals containing z centers

Results of measurements of the temperature dependence of dielektric losses (tan δ) in KCl:SrCl₂, KCl:CaCl₂ and NaCl:CaCl₂ samples after electrolytic coloration, after F → Z₁ conversion and Z₁ → Z₂ conversion are reported. In agreement with Rosenberger-Lüty model, Z₁ centers display dipolar character due to the presence of the ordinary Me²⁺-cation vacancy dipole with adjacent F center. The changes of tan δ after Z₁ → Z₂ conversion point to the release of a free cation vacancy from the former dipole.     

Physicochemical transformations in multicomponent melts containing uranium,zirconium, and iron oxides and calcium silicates and aluminates

The properties and crystallization nature of melts of the U⁴⁺–U⁶⁺–Zr⁴⁺–Fe²⁺–Fe³⁺–Ca²⁺–Si⁴⁺–Al³⁺–O^2– system were studied. It was found that the main factors changing the physicochemical characteristics of the melt are the concentration and valence state of uranium and the concentrations of iron oxide and silicon oxide. The results obtained in the analysis of the physicochemical properties of the multicomponent melt can be used in nuclear power engineering to preclude disintegration of a WWER type nuclear reactor in the course of a hypothetical severe reactor accident.