Stable single-mode operation of a Q-switched laser by a simple resonator length control technique

A simple extension to the technique of “pre-lase” Q-switching ensures that a TEM₀₀ mode, Q-switched NdYAG laser produces single longitudinal mode oscillation on every shot.     

Studies on nucleation from solution of some analytically important metal chelates-II Nickel dimethylglyoximate

A new direct-mixing and rapid particle-counting system useful for studies on crystal nucleation solution is described. The methods used to calibrate and evaluate the system are reported together with the results obtained during studies on nucleation from solution of nickel dimethylglyoximate. The Volmer-Weber, Becker-D?ring model of the nucleation process is used to correlate the results.     

A two-step Q-switching technique for producing high power in a single longitudinal mode

An electro-optic Q-switch has been opened in two steps to allow slow pulse build-up giving, in conjunction with a resonant reflector, a high degree of mode selection in a way analogous to the use of saturable absorbers. Using this technique, a flash pumped NdCaWO₄ laser has produced reliable operation in a single longitudinal and transverse mode with an output power of 250 kW.     

Spuren von Zink in Lebensmitteln

Ohne Zusammenfassung     

Spectrographic determination of trace elements in cement

Summary A simple straight-forward spectrographic method is extended to the analysis of cement to cover elements of general interest to cement industry and to non-metallic materials. A d.c. arc of 9 amperes at 220 volts is used to determine the elements Mg, Sr, Ba, V, Nb, and Mn with reasonable detection limits using the visible region of the Hilger spectrograph. The sensitivity of the method is satisfactory and the precision is unusually good for a routine quantitative analysis.

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Zusammenfassung Obwohl im Schrifttum eine Reihe von Untersuchungen über die spektrochemische Bestimmung von Spurenelementen in Silicaten und Zement vorliegt, ergeben sich bei der praktischen Anwendung dieser Analysenvorschriften Schwierigkeiten.Im vorliegenden Verfahren war der Verzicht auf die Veraschung der Mischung der spektralanalytischen Proben mit Graphit deshalb notwendig, weil einige Elemente, wie z.B. Mg, Sr, Ba, V, Nb, Cr und Mn, auf direktem Weg im Zement quantitativ bestimmt werden. Die Nachweisempfindlichkeit beträgt etwa 10 ppm für die meisten Elemente mit einem mittleren Fehler von 3,0–8,0%.