Effect of pressure on the Kondo temperature of Cu(Fe)

The electrical resistivity of Cu with Fe impurities has been measured from 1.4 K–40 K under pressures to 82 kbar. When plotted versus the reduced temperature T/T_K, the data at all pressures overlap, confirming the existence of a universal resistivity curve.     

meso‐2,2′‐Di­phenyl‐3,3′,4,4′‐tetra­hydro‐2,2′‐bi­furan‐5,5′(2H,2′H)‐dione

The crystal structure of the title compound, C₂₀H₁₈O₄, contains a crystallographic inversion center. The C—C bond linking the two halves of the mol­ecule is slightly elongated at 1.577 (3) Å.     

Effects of intrinsic anharmonicity in the Mie–Grüneisen equation of state and higher order corrections

The usual quasiharmonic Mie–Grüneisen (MG) equation of state is modified by the inclusion of ‘intrinsic anharmonicities’, which have been considered up to now primarily in the high temperature limit. A comparison with experimental data for the rare gas solids, Ar, Kr and Xe and for MgO reveals that the anharmonic contributions cannot be represented perfectly within the MG approximation. A small but significant modification of the MG approach is presented to estimate intrinsic anharmonic contributions within a mean-field approximation for the thermal part of the internal energy. This estimate results in reasonable interpolations to low temperatures, where quantum effects are dominant. The present approach is also compared with more restricted recent theoretical results.     

Reactions of Vinylnitrosonium Ions with some Aromatic Heterocycles - Electrophilic Substitution vs Cycloaddition

Reaction of N-cyclohexyl-N-propenyl-nitrosonium ion and N-cyclohexyl-N-ethenylnitrosonium ion with indole and N-methylindole resulted in electrophilic substitution while reaction of the former with skatole, benzothiophene and benzofuran resulted in cycloaddition.     

Precise force measurement over 6 decades applying the resonator-internal photoelastic effect

Mechanical forces can be measured over a range of 6 decades by applying the photoelastic effect inside the laser cavity. Our experiments with a modular test setup (633nm) demonstrate proportional force-to-frequency conversion from 1·10^–4N up to 80N with the noise equivalent resolution of 3·10^–5N. The frequency response of our test setup was established from dc up to some kilohertz. Measurement range and resolution can be extended to 10^–6N or smaller values by applying improved laser stabilization and miniaturizing cavity length and size of photoelastic material. The upper limit of the scale factor is calculated to be of the order of 25MHz/N.     

The effect of pressure on lattice parameter,magnetic susceptibility and reflectivity of SmS

The lattice parameter of SmS single crystals has been measured under hydrostatic pressure up to 70 kbar. The fit for the metallic phase by means of the Birch equation gives an unusually large pressure derivative of the bulk modulus B' = 11 and hence a large pressure dependence of B. No change in the nonmagnetic intermediate valence state of Sm is observed up to 24 kbar as concluded from our magnetic susceptibility measurements. Reflectivity measurements under hydrostatic pressure p > 6.5 kbar show a small plasma edge shift (～0.08 eV) towards lower energy upon cooling from 77 to 4.2 K. Hence the low temperature resistivity anomaly is attributed to an enhanced conduction electron scattering.     

Coulometrische titration von hypochloriten und chloraten

Hypochlorite was determined by direct coulometric titration with iron(II) in an acetate buffered solution. Chlorate was titrated with titanium(III) in 2M hydrochloric acid. Amperometric indication with one and two electrodes, respectively, was used. Mixtures of hypochlorites and chlorates, e.g., in industrial electrolytes, may be analysed. On a déterminé l'hypochlorite par titrage coulométrique direct avec le fer(II) dans une solution tamponnée à l'acétate. On a titré le chlorate avec le titane(III) en acide chlorhydrique 2M. On a utilisé l'indication ampérométrique une et deux électrodes respectivement. On peut analyser des mélanges d'hypochlorites et de chlorates, par exemple dans des électrolytes industriels.