Identification of low molecular vaporizable components in silicone resins using gas chromatography/mass spectrometry

An experimental set-up for the detection of elemental chlorine in chlorinated hydrocarbons (CHCs) is described based on a miniaturized system, which could be used for on-line monitoring of chlorinated compounds. With an optimized time-resolved detection chlorine from CHCs like CCl₄ can be determined by Laser-Induced-Breakdown-Spectroscopy (LIBS) with g/g-detection limits in the gas phase. The application of a miniaturized Nd : YAG laser resulted only in a minor loss in performance, hence it could be used for designing a rugged and small on-line sensor. In addition, preliminary results for the detection of chlorine via the formation of CuCl in the plasma formed by focussing the laser on a copper surface are reported. Utilizing the luminescence of the CuCl D-system at 440 nm, a tenfold improvement in the detection limits was obtained. It appears that the formation of ad hoc selected, small molecules in a laser plasma could be a promising alternative for the selective and sensitive analysis of gaseous chlorinated and other species.     

Brillouin scattering and rotation translation coupling of (KCN)xX1−x mixed crystals

Brillouin scattering is used to study the concentration and temperature dependence of longitudinal and transverse phonon frequencies of KCN_χBr_1?χ, KCN_χC1_1?χ, and KCN_0.85I_0.15 mixed crystals. Unlike pure KCN, mixed crystals with χ < 0.7 show no phase transition upon cooling, and the transverse acoustic frequency ω_TA(110) displays a minimum at some characteristic temperature T_i.T_i is below the phase transition of pure KCN and depends on the C1^? concentration. The Brillouin data are discussed in terms of coupling of the acoustic phonons with orientational motion of CN^? ions and mean field theory.     

Minor components with the γ-cyclogeranil geraniol skeleton from Bellardia trixago (L.) all.

Trixagol 1 and fourteen derivatives with the skeleton of γ-cyclogeranil geraniol were isolated from Bellardia trixago, the structures were determined by spectroscopic methods and confirmed by partial synthesis. Furthermore. 3,4-dihydro-γ-ionone, α-ambrinol, β-sitosterol and three flavonoids 5-O-demethyl tangeretin, 5-hydroxy auranetin and 3′-methoxy calycopterin were also isolated.