Laser-induced stabilization

Research has led to alloys which undergo laser-induced crystallization within about 50 ns. This is possible, for example, with TeGe alloys, which also possess the necessary temperature stability up to 180°C and exhibit sufficient reflection (crystalline phase) and transmission characteristics (amorphous phase), respectively. TeGe alloys have not found a practical use because of the formation of depressions in the memory layer typical for them after repeated... 

In order to get more insight into the factors that determine thermal stability, which is crucial for the safe manipulation of (fluoromethyl)silanes, we have investigated the conventional thermal [24] and laser-induced decomposition [25, 26] of the parent silanes F H3 CSiH3. These compounds are stable gases at ambient temperature, and they may be conveniently studied by IR and multinuclear NMR spectroscopy. Therefore these appear to be particularly suited for gas phase investigations. 

An important application of the heated flat-flame burner is the photolytic perturbation of the post cool-flame gases downstream from the stabilized cool-flame of n-heptane [83]. The chemical perturbation was initiated by an incident laser beam which dissociated H2O2 to OH radicals. The relaxation of the excess OH, measured by laser induced fluorescence, was shown to be tied to the principal reaction modes in alkane oxidation, namely propagation, termination and net branching. Global rate parameters were quantified from the decay curves. 

Spectroscopic methods are required for free radical intermediates. Laser induced fluorescence of hydroxyl radicals has been used successfully to determine elementary rate parameters associated with the isomerization reaction RO2 QOOH [113]. Laser perturbation of hydroxyl radical concentrations in stabilized cool-flames has been used to obtain global kinetic data for chain-branching rates at temperatures of importance to the low-temperature region [79]. These methods appear to be most suited at present to combustion studies in flow systems. There are also several studies of the relative intensity from OH radical fluorescence during oscillatory cool-flames [58,114]. 

Bitea et al. [2003BIT/MUL] discuss the stability of thorium colloids generated by cou-lometric titration of 10 to 10 M thorium solutions at pH 3 - 5 in 0.5 M NaCl. Using laser-induced breakdown detection (LIBD) and ultrafiltration the colloids formed above the solubility limit of Th(lV) hydroxide were found to be stable within the time period of investigation (up to more than 400 days). Dilution of colloid containing test solutions at constant pH leads to the degradation of colloids into soluble ionic species, whereas dilution with neutral 0.5 M NaCl results in increased over-saturation and colloid formation, as recognised by a pH shift to lower values. This observation was ascribed to the simplified reaction ... 

When taken orally, the stabilized form of NADH is absorbed in the small intestine. Stndies have shown that NADH passes the intestinal mncosa undegraded by passive diffusion. In a further study, it was demonstrated that ENADA-NADH passes the blood-brain barrier. When rats were fed with two tablets ENADA-NADH (5mg) an increase of the NADH level in the brain cortex was observed after 20min of intake as measured by laser-induced fluorescence. ... 

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