Static quenching technique

For the boron-nitrogen system, because the high gas pressure is required for the synthesis, it is difficult to apply any dynamic method for investigation of the microstructural transformations, which occur in the combustion front. Thus, the static quenching technique was used [26, 23, 27]. The idea of this method is to extinguish the combustion wave and quickly cool the sample it is necessary to freeze all zones with the characteristic microstructure, chemical and phase structure of the reactants, intermediates, and final products. For quenching to take place, the heat loss from the reaction front at some point must exceed the critical... 

The commercialization of inexpensive robust LED and laser diode sources down to the uv region (370 nm) and cheaper fast electronics has boosted the application of luminescence lifetime-based sensors, using both the pump-and-probe and phase-sensitive techniques. The latter has found wider application in marketed optosensors since cheaper and more simple acquisition and data processing electronics are required due to the limited bandwidth of the sinusoidal tone(s) used for the luminophore excitation. Advantages of luminescence lifetime sensing also include the linearity of the Stem-Volmer plot, regardless the static or dynamic nature of the quenching mechanism (equation 10) ... 

Previous workers had used the molecular beam TOF technique (134) and the VUV flash photolysis LIF technique (135). Ling and Wilson (136) had suggested that either the A(2n) state of CN is produced in the original photolysis process or that I atoms were produced in the Pi/2 and 3/2 states. It had been previously shown (135), by collisional quenching studies, that the A state of CN was not produced. This earlier work has been reviewed by Baronvaski (137) but recently both he and others have done further work on this molecule using excimer laser sources in both static gases and pulsed molecular beams. 

At very low water content (wo=0-2) the porphyrins (ZnTPP and ZnTPPS4 ) are located at the interface and are dynamically quenched by duroquinone (DQ), which is solubilized in the organic phase, with observed rate constants of k=9.1><109 dm3 mol 1 s 1, ZnTPP/DQ, wo=0 and kq= =1.9><109 dm3 mol s ZnTPPS4-/ DQ, w0=2. However, a quencher bound at the interface like anthraquinone-2-sulphonate (AQS) interacts statically with ZnTPP at the interface as shown by steady-state and transient fluorescence techniques (Table 2)... 

Various spectroscopic techniques and probes have been used to investigate solubilization of probe molecules, mostly using UV/visible spectroscopy, fluorescence spectroscopy, ESR spectroscopy [64, 74, 217, 287] and NMR-spectro-scopy [367-369]. Fluorescence spectroscopy is particularly versatile [370], as various static and dynamic aspects can be covered by studying excitation and emission spectra, excimer or exciplex formation, quantum yields, quenching, fluorescence life-times, fluorescence depolarization, energy transfer etc. 

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