Infrared and Raman spectroscopy of particle-beam induced damage of silicon carbide

The damaging of 6H-SiC by ion implantation (Ar⁺, 320 keV) leads to the formation of a light-absorbing surface layer with a thickness of about 0.4 μm and a dielectric function which indicates a disordering of the crystal structure. Raman spectra show the existence of amorphous carbon, silicon and silicon carbide. Ion bombardment with 1.4 MeV He⁺ ions generates a 3 μm thick surface layer with small lattice distortions and light-absorbing centers and a 0.4 μm thick interface layer with a larger refractive index.     

Determination of the strange quark content of the nucleon from a next-to-leading-order QCD analysis of neutrino charm production

We present the first next-to-leading-order QCD analysis of neutrino charm production, using a sample of 6090 ^– and -induced opposite-sign dimuon events observed in the CCFR detector at the Fermilab Tevatron. We find that the nucleon strange quark content is suppressed with respect to the non-strange sea quarks by a factor =0.477 _–0.053 ^+0.063 , where the error includes statistical, systematic and QCD scale uncertainties. In contrast to previous leading order analyses, we find that the strange seax-dependence is similar to that of the non-strange sea, and that the measured charm quark mass,m _c =1.70±0.19 GeV/c², is larger and consistent with that determined in other processes. Further analysis finds that the difference inx-distributions betweenxs(x) and is small. A measurement of the Cabibbo-Kobayashi-Maskawa matrix element |V _cd |=0.232 _–0.020 ^+0.018 is also presented.     

Absorption und Adsorption

Ohne Zusammenfassung     

Catalytic enantioselective transamination of alpha-keto esters: an organic approach to enzymatic reactions

The half-transamination reaction of alpha-keto esters with pyridoxamine or 4-picolylamine was found to be catalysed by different metal catalysts in organic solvents giving moderate yields and enantioselectivities of up to 37% ee for methyl-3-indole pyruvate.