Test of charge conjugation invariance

We report on the first determination of upper limits on the branching ratio (BR) of eta decay to pi0pi0gamma and to pi0pi0pi0gamma. Both decay modes are strictly forbidden by charge conjugation (C) invariance. Using the Crystal Ball multiphoton detector, we obtained BR(eta-->pi0pi0gamma)<5 x 10(-4) at the 90% confidence level, in support of C invariance of isoscalar electromagnetic interactions of the light quarks. We have also measured BR(eta-->pi0pi0pi0gamma)<6 x 10(-5) at the 90% confidence level, in support of C invariance of isovector electromagnetic interactions.     

Synthesis, structure, and nonlinear optical properties of diarylpolyynes

A series of alpha,omega-diarylpolyynes has been synthesized. In addition to the synthesis of three hexaynes (3a-c), a notably improved synthesis of 1,16-diphenylhexadecaoctayne (5) is described. The third-order nonlinear optical characteristics for these molecules have been studied and show a substantial increase in molecular hyperpolarizability (gamma) as a function of increasing length. The unusual solid-state structures of compounds 3a and 3b are reported.     

Superdeformed bands in193Hg and194Hg

By analyzing the thick target yield curve of resonant (p,γ) reactions on²³Na and²⁶Mg for various target temperatures within a Monte Carlo approach, we are able to define the Debye and Einstein temperature of the target material in the surface region. The obtained surface temperatures are noticeably higher than the respective calorimetric values.     

Temperature dependence of C3(X1Σg+) reactions with alkenes and alkynes, 295-610 K

C₃ reaction rates with ethene, acetylene and various of their alkyl-substituted derivatives are measured in the temperature range 295–610 K. Reactions with ethene and acetylene have 6–8 kcal/mol activation energies which become negative for the multiply alkyl-substituted species. The reaction chemistry of C₃ is compared with similar species and we conclude that the mechanism involves electrophilic addition at the carbon-carbon multiple bond. Reaction rates are apparently pressure independent over the range of 5–100 Torr.     

Tests of models of molecular reorientation in liquids

Computer simulations of tetrahedral molecules have been used to test some common models for molecular reorietation in liquids. At high density, the Fokker—Planck and J-diffusion models and a three-term Mori approximation are all unsatisfactory; the two latter provide reasonable fits at low density.     

Chelation-controlled nucleophilic additions. 1. A highly effective system for asymmetric induction in the reaction of organometallics with α-alkoxyketones.

An optimum reaction system is described for the highly stereoselective addition of carbanionic nucleophiles to chiral α-alkoxyketones. A variety of oxygen protecting groups are acceptable and allow chelation-controlled α-asymmetric induction with diastereomeric product ratios ranging from 50->200:1.     

Angular momentum,statistical equilibrium and sequential fission in very asymmetric systems

The in-and out-of-plane angular distributions for fission fragments in coincidence with projectile-like products from the reaction of 252 MeV²⁰Ne with¹⁹⁷Au and²³⁸U have been measured. The results are compared to a statistical model which has successfully explainedγ-ray anisotropies from a heavy symmetric system. The agreement is rather good after proper consideration of the direction of the line-of-centers at contact.     

Photometric determination of ruthenium with 3-nitroso-2,6-pyridinediol

Summary A highly sensitive photometric method has been developed for the determination of ruthenium. The method is based on the purple colored complex formed when ruthenium is heated with 3-nitroso-2,6-pyridinediol (NPD) in slightly acidic solution. The molar absorptivity of the purple complex is 2.6 · 10⁴l.mole^–1,cm^–1. The reaction ratio is 31 reagent to ruthenium.

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Zusammenfassung Eine sehr empfindliche photometrische Methode zur Rutheniumbestimmung wurde ausgearbeitet. In schwach saurem Medium bildet Ruthenium beim Erhitzen mit 3-Nitroso-2,6-pyridindiol (NPD) einen purpurroten Komplex. Dessen molare Absorption beträgt 2,6 · 10⁴ l/Mol.cm. Reagens und Ruthenium reagieren im Verhältnis 31.