We report a novel optoacoustic detection scheme which is suited for use with low-power radiation sources. The improved detection capability is demonstrated for SO2 with a frequency-doubled dye laser of 1 mW uv output power, allowing the detection of SO2 concentrations as low as 0.12 ppb.
Doping of alkali halides with large amounts (10−3 to 10−2) of OH− defects can be used to drastically increase the production and stabilization of F 2+ centers. Under electron irradiation, the coloration efficiency and F2:F ratio is increased, and the OH− defect is decomposed into various substitutional and interstitial hydrogen and oxygen defects, part of which work as electron traps. As a consequence, optical ionization of F2 centers leads to stable F 2+ center production, as tested in LiF, NaF, NaCl, KCl, and KBr hosts. Tuneable laser operation is achieved for the first time for F 2+ centers in NaCl and KCl using this technique. A systematic study into the decomposition kinetics of OH− defects is started, which reveals the existence of a new hydrogen defect, identified by its ir local mode absorption, which may play the crucial role in the F 2+ stabilization.
~ultichannel fast scanning diode array spectrometers represent a new class of spectroscopic tnstruments. They feature a unique combination of novel technologies, speed, comfort in handling, and ease of operation. In a research study the potentials of this powerful instrument in the field of m!croscope photometry are evaluated. As examples for possible applications the results of typIcal spectral measurements in absorption and reflection, including film-thickness determination of microstructured semiconductor layers, are presented.
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