Experimental survey of the sticking problem in muon catalyzed dt fusion

The sticking process dt + n, which constitutes the most severe limit to the number of fusions which a muon can catalyze, is reviewed. Many attempts were made to determine by calculations and measurements the probability for initial sticking _s ⁰ (immediately after dt fusion) and for final sticking _s (after the came to rest). Previous results based on neutron disappearance rates and on the observation of -X-rays were controversial and also in some disagreement with theory. New data are reported from PSI on direct observation of final sticking, using a setup with the St. Petersburg ionization chamber. These data mark a significant improvement in reliability and may clarify questions concerning previous discrepancies. The new results is _s(0.56±0.04)%, lower than the theory prediction _s=(0.65±0.03)%, at medium density.     

DFT/MRCI assessment of the excited-state interplay in a coumarin-schiff Mg2+ fluorescent sensor

Fluorescent sensors with selectivity and sensitivity to metal ions are an active field in supramolecular chemistry for biochemical, analytical, and environmental problems. Mg²⁺ is one of the most abundant divalent ions in the cell, and it plays a critical role in many biological processes. Coumarin-based sensors are widely used as desirable fluorophore and binding moieties showing a remarkable sensitivity and fluorometric enhancement for Mg²⁺. In this work, density functional theory/multireference configuration interaction (DFT/MRCI) calculations were performed in order to understand the sensing behavior of the organic fluorescent sensor 7-hydroxy-4-methyl-8-((2-(pyridin-2-yl)hydrazono)methyl)-2H-chromen-2-one (PyHC) in ethanol to solvated Mg²⁺ ions. The computed optical properties reproduce well-reported experimental data. Our results suggest that after photoexcitation of the free PyHC, a photo-induced electron transfer (PET) mechanism may compete with the fluorescence decay to the ground state. In contrast, this PET channel is no longer available in the complex with Mg²⁺ making the emissive decay more efficient. © 2019 Wiley Periodicals, Inc.     

Triphenylphosphine in Some Nucleophilic Additions to Double Bonds Containing Electrophilic Carbon

Abstract

Phosphorus (III) componds like 1 possess basic and nucleophilic properties (phosphonium salt formation) as well as SET properties (i.e. reduction of peroxides). Typical examples of both reaction types are discussed in schemes I and II.     

Ueber die Hydratation natürlicher und künstlicher Gläser

Ohne Zusammenfassung Gerhart Schott, Ueber die Hydratation natürlicher und künstlicher Gesteinsgl?ser. Inaug.-Diss. (Jena 1923). Unver?ffentlicht.     

Die chemische Analyse mit Membranfiltern

Ohne Zusammenfassung     

Muon transfer from protium to helium isotopes at low temperature

The transfer reaction of negative muons from muonic protium to ³ and ⁴ in binary and triple gas mixtures was studied. In the binary mixtures the transfer rates to the two helium isotopes were determined from the time distribution of the 7-keV X-rays of the intermediate muonic molecule (pμHe)*. The experimental transfer rate to ⁴ is in good agreement with theoretical predictions, whereas the rate to ³ is a factor 2 to 3 smaller than the predicted ones. Radiative branching ratios of the (pμHe)8 molecular decay were obtained. Muon transfer from excited states of muonic protium gives the main contribution to the total intensity of the μHe Lyman series in the binary mixtures. Values of q _1s ^He are determined. This revised version was published online in August 2006 with corrections to the Cover Date.