Intensive fluctuation region

3 EXPERIMENTAL RESULTS AND DISCUSSION 11.3.1 Intensive fluctuation region 

Pressure fluctuation has the effect of promoting chemical reaction(s). Therefore the spatial profile of the intensive fluctuation region inside the reactor is significant for 

However, the experimental results are completely unexpected. The profiles of PSn on the horizontal and the vertical planes measured at an impinging velocity of n0 = 0.1 m s 1 are shown in Figs. 11.4 and 11.5 and those on the impingement plane and its parallel planes in Fig. 11.6. 

As can be expected, the intensive fluctuation region is symmetrical with respect to the impingement plane, provided the two streams leaving the drawing tubes are at the same velocity. This is simply because the two sides of the reactor have the same structure. In addition, the figures also show that the region is essentially symmetrical about the flow axis, suggesting that the above assumption is reasonable. 

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Figure 11.7 Profile of intensive fluctuation region in the space between drawing tubes.

On the other hand, the experiments above yield a profile of the intensive fluctuation region as shown in Fig. 11.7. It is considered that the fluctuation results from the impingement between the two opposing streams and that the fluctuation intensity... 

As can be seen from the results given above, the intensive fluctuation region is concentrated mainly in the cylinder between the outlets of the drawing tubes. For convenience, let us define the integral intensity of the intensive region, denoted by 7P, as... 

Figure 11.11 Influence of un on the integral intensity of intensive fluctuation region.

The intensive fluctuation region is concentrated between the outlets of the drawing tubes and around the flow axis, and takes the form of a couple of truncated cones with an empty core and with coinciding bottoms. The region is symmetrical with respect to both the impingement plane and the axis of the streams and is essentially independent of nn. The space surrounded by the external surface of the cones is defined as the impingement zone. 

A laser beam highly focused by a microscope into a solution of fluorescent molecules defines the open illuminated sample volume in a typical FCS experiment. The microscope collects the fluorescence emitted by the molecules in the small illuminated region and transmits it to a sensitive detector such as a photomultiplier or an avalanche photodiode. The detected intensity fluctuates as molecules diffuse into or out of the illuminated volume or as the molecules within the volume undergo chemical reactions that enhance or diminish their fluorescence (Fig. 1). The measured fluorescence at time t,F(t), is proportional to the number of molecules in the illuminated volume weighted by the... 

A strong reduction in the spectral and intensity fluctuations was observed when QDQWs of CdS and HgS were compared with pure CdS particles in single-particle emission studies [304]. This, again, was explained by charge carrier localization in the HgS region of the nanocrystals. 

The analysis performed allows one to judge qualitatively about the processes, which go on in a spectrum when the Stark structure of rotational transitions is averaged by fluctuations of the orienting field. If y decreases, x being fixed, the resolved Stark structure with the intense Q-branch in the centre transforms into the spectrum of a quasi-free rotator. If x < 1, the spectrum may be singlet in the intermediate region. 

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