Experimental enhancement factor

Fig. 23. Comparison of predicted and experimental enhancement factors for the experimental conditions of Fig. 19. Curves designated 1 and 1 are for vL = 0.86 mm/s, while curves 2 and 2 are for vL = 1.65 mm/s. The prime designates the data fits in Fig. 19. (Figure from Stcgasov et at., 1992, with permission, 1992 Elsevier Science Publishers.)...

Table 14.1 Experimental enhancement factors of QDs fluorescence emission observed with the different gold nanopattems triangular prisms and cylinders with 100- and 200-nm lateral dimensions (35 nm height). The reported enhancement factors were normalized over the correspondent spatial duty cycles.

Table II. Comparison of Analytical and Experimental Enhancement Factors... 

Experimental enhancement factor and the DeCoursey formula enable evaluation of the surface renewal rate and physical area-based mass transfer coefficient, k. Interfacial area can then be determined from the measured values of the volumetric mass transfer coefficient and the predicted value of the area-based mass transfer coefficient ... 

FIG. 5 Enhancement factor observed in the forward rate constant for TMA ( ) and TEA ( ) ion transfer at the water-nitrobenzene interface due to the presence of different PCs. (Experimental data are taken from Ref. 11 and correspond to 30°C.)... 

Figure 23 shows a simulation of Haure s periodic flow interruption data at time-average u = 0.86 mm/s (Curves 1 and 1 ) and u = 1.65 mm/s (Curves 2 and 2 ). Data points and the fit (dashed line) are from Fig. 19. The simulation predictions are 28 to 35% too high, which is not bad considering the 25% variation in the experimental data shown in Fig. 19. The trends, however, are not properly represented. Figure 23 predicts enhancement factors declining with r, whereas data indicate an increase at low r and...

The signal enhancement due to this approach can, in principle, be as high as 105-fold - that is, equal to the reciprocal Boltzmann factor however, the experimentally achievable enhancement factors typically range between 10 and 103. Thanks to this increase in sensitivity, the PHIP phenomenon, therefore, provides for a powerful tool to investigate the fate of the dihydrogen, the catalysts, and of the substrates during hydrogenation reactions. 

The enhancement factors mz and mx can be calculated exactly by Hansen s formulas for optics of thin multilayer film [10]. The results of the calculation for our experimental systems are shown in Figure 9 as a function of wavenumber. Three lines for the mz values and those for the mx values refer to the refractive indices of the LB film, 1.4, 1.5, and 1.6. The mx values are very small and about one percent of the mz values. This means that the electric field generated by the RA measurements is practically perpendicular to the film surface, as was mentioned above. 

Equation (6) links, in a simple way, the thermodynamically important stability constants Kox and /Cred of a complex in different oxidation states with experimentally measurable redox potentials EH and EHa. Therefore it provides an easy way to obtain the ratio of KoxIKted, which is a theoretically useful parameter known as the binding enhancement factor (BEF). We propose that a better description for this ratio would be the reaction coupling efficiency (RCE) since binding by so-called molecular switches may be reduced or enhanced, depending upon the particular system involved. Equation (6) also allows the calculation of Kox if Kted is known or vice versa. 

In the context of the symmetry correlation schemes in Table 5, the experimental determination of enhancement factors for the individual elements, EF( C) and EF( 0), are more relevant than the directly measured EF(89) and EF(90). Because the experiment is done under natural abundance conditions, EF(90) can be taken... 

Fig. 49. The dependence of the enhancement factor of catecholamine derivatives on the carbon number of n-alkyl sulfates as the hetaerons. The straight line obtained by least-squares analysis fits the expression, logi 0.22S ( 0.0317)Af where is the enhancement factor and N is the carbon number. The intercept is zero within experimental error. Reprinted with permission from HorvAth et al, (S4), Anal. Chem. Copyright 1977 by the American Chemical Society.

The problem now reduces to finding how ra is related to the experimental parameters. The gas supply functions for different tip geometry have already been discussed in Section 2.1.2 and they are given by eqs (2.9), (2.11) and (2.12). zs is the total gas supply function Z multiplied by sa/A where sA is the cross-section of a surface atom in capturing an incoming gas atom, and A is the total area of the gas supply function. For a large field enhancement factor, = aF2/2kT, zs can be approximated by... 

The acceleration of mass transfer due to chemical reactions in the interfacial region is often accounted for via the so-called enhancement factors (27,68,69). They are either obtained by fitting experimental results or derived theoretically on the grounds of simplified model assumptions. It is not possible to derive the enhancement factors properly from binary experiments, and significant problems arise if reversible, parallel, or consecutive reactions take place. 

---