Fluorescence of fly ash samples: Implications for in situ and remote detection

A study of the fluorescence spectra of fly ash samples from different sources has shown that each samples has a characteristic fluorescence and excitation spectrum which could be used to identify and monitor its presence. Fluorescence lifetime studies of samples from different sources have demonstrated characteristic features which can be used for identification. The fluorescence method should be useful for in situ and remote monitoring applications.     

Starke verdrillungen trotz schwacher sterischer hinderung

Considerable twisting of weakly hindered hydrazonyl radicals is explained on the basis of a low barrier to rotation due to compensation of the loss of π-π-delocalization on twisting by gain of π-σ-delocalization.     

Observation of two-electron-one-photon transitions in silicon

We report on the observation of Kαα X-rays of Si, produced in collisions of 15–28 MeV Si projectiles with various target atoms in the range Z = 6 to 29. Energy shifts of X-rays were measured and are compared with theoretical predictions. Cross section ratios for emission of Kαα and Kα radiation are given.     

Search for ΔS = 2 decays of neutral Ξ-hyperons

A search for the decay Ξ⁰→pπ^? has been performed in a neutral hyperon beam derived from the 24 GeV/c external proton beam at CERN. The experiment gives as a 90% confidence upper limit for the branching ratio $\text{Γ(Ξ}{}^0\text{→pπ}{}^{\mathrm{?}}\text{)}\text{Γ(Ξ}{}^0\text{→Λπ}{}^0\text{)<3.6×10}{}^{\mathrm{?5}}$.