The maximum entropy determination of nuclear densities of calcium isotopes from elastic scattering of alpha particles

Radial moments of the real part of the optical potential for elastic scattering of 104 MeV α particles are used as constraints, in determining the nuclear density of maximal entropy. The potential is related to the density by the folding model.     

Strukturaufklärung eines Dimethylfulven-Trimeren. Hinweis auf eine [6 + 4]-Cycloaddition von 6, 6-Dimethylfulven

Structure Elucidation of a Dimethylfulvene-trimer. Evidence for a [6+ 4]-Dimerization of 6, 6-Dimethylfulvene Thermal reaction of pure 6, 6-dimethylfulvene ( 1c ) at 60° gives an oligomeric mixture consisting mainly of fulvene-trimers. The structure of the main product 3c is partially elucidated by ¹H-NMR. investigations at 400 MHz and definitely confirmed by X-ray analysis. The formation of 3c is explained in terms of a [6+4] dimerization, followed by a 1, 5-proton-shift and a final Diels-Alder reaction.     

The temperature dependence of piezoelectric constants eiμ of μ-quartz

Measurements of the temperature dependence of e₁₁ and e₁₄ of α-quartz relative to room temperature based on thichkness mode resonances and antiresonances show that e₁₄ changes its sign at ≈360°C. Fair agreement of e₁₁ with values reported in earlier work was found.     

Lifetime measurements on excited states in100Rh

Lifetime measurements of three excited states in¹⁰⁰Rh populated by the decay of¹⁰⁰Pd have been carried out. A two parameter delayedγ-γ-coincidence experiment using an intrinsic Ge and a plastic scintillation detector resulted in the following values:T _1/2(32.72 keV,¹⁰⁰Rh)=(27.6 ±0.6) nsT _1/2(74.8keV,¹⁰⁰Rh)=(213.6±2) nsT _1/2(158.8 keV,¹⁰⁰Rh)<0.5 ns. For the levels at 32.72 keV and 158.8 keV no former values are known.     

Photorearrangement of alpha-azoxy ketones and triplet sensitization of azoxy compounds

[reaction: see text] Although some aspects of azoxy group radical chemistry have been investigated, unhindered alpha-azoxy radicals remain poorly understood. Here we report the generation of alpha-azoxy radicals under mild conditions by irradiation of alpha-azoxy ketones 4a,b. These compounds undergo alpha-cleavage to yield radicals 5a,b, whose oxygen atom then recombines with benzoyl radicals to produce presumed intermediate 15. Formal Claisen rearrangement gives alpha-benzoyloxyazo compounds 8a,b, which are themselves photolabile, leading to both radical and ionic decomposition. The ESR spectrum of 5a was simulated to extract the isotropic hyperfine splitting constants, which showed its resonance stabilization energy to be exceptionally large. Azoxy compounds have been found for the first time to be good quenchers of triplet excited acetophenone, the main sensitized photoreaction of 7Z in benzene being deoxygenation. While this reaction has been reported previously, it was always in hydrogen atom donating solvents, where chemical sensitization occurred. The principal direct irradiation product of 4bZ and model azoxyalkane 7Z is the E isomer, whose thermal reversion to Z is much faster than that of previously studied analogues.