Capillary power spectrum

First, a typical power spectrum of capillary waves excited at the W/NB interface is shown in Figure 3.4a. The errors on the values of the capillary wave frequency were 0.1 kHz, obtained as the standard deviation of 10 repeated measurements. Capillary wave frequency dependence on CeHsONa is shown in Figure 3.4b. The frequency decreased significantly with increasing CeHsONa concentration. This indicated that interfacial tension was decreased by the interfacial adsorption of CeHsONa. 

FIGURE 3.4. (a) Power spectrum for capillary waves excited at the W/NB interface (238 K). (b) Capillary wave frequency dependence on the concentrations of CsHsONa (283 K). 

Fig. 5. Typical power spectrum of the optically mixed light intensity. O/W, ripplon (capillary wave) frequency at nitrobenzene-water interface W/A, ripplon frequency at water-air interface. (Reprinted from [76] with permission. Copyright The Japan Society of Analytical Chemistry).

Figure 3.16. The power spectrum of capillary waves on a liquid surface with the following properties yo = 50 mNm , y = 2 X 10 mNsm", o = 10 mNm , a = 0 mN s m . The inset is the heterodyne correlation function of this power spectrum.

High-pressure mercury lamps operate at pressures about 10 atmospheres and essentially two types are used in industrial applications. The point source lamp focuses on a small-diameter spot, thus delivering an intense radiation to that spot. The capillary lamp is used for narrow webs up to approximately 20 cm (8 in.) wide.4 They are capable of producing a wider spectrum than the medium-pressure lamps and operate with higher power (150-2880 W/cm). Their disadvantage is a relatively short operating life, typically hundreds of hours. 

The use of mass spectrometry (MS) as a detection system is inevitable in the evolution of any separation method, especially CE where the liquid flow rate ( 1 ml/min) is compatible with conventional mass spectrometers. The combination of a high-efficiency liquid-phase separation technique, such as capillary electrophoresis, with MS detection provides a powerful system for the analysis of complex mixtures. Analyte sensitivity and the mass spectrum obtained depend on the electrospray ionization (ESI) voltage, ion-focusing parameters, and buffer composition. In general, the greatest sensitivity is obtained by employing conditions that facilitate desolvation and minimize cluster formation.47 Three ways of interfacing for CE-MS... 

The identity of a compound can often be determined by gc, if an unknown has the same retention time, and co-runs with a known compound when the two are injected as a mixture, but just as with tic and hplc co-rurming, caution should be exercized. A very powerful structure analysis technique is gc mass spectrometry (gc-ms) and when capillary gc is used this is a very simple and quick form of analysis. The mass spectrometer simply acts as the detector, but as well as providing a chromatograph, a mass spectrum of each individual component is obtained. Capillary gc-ms... 

More recently, Samec and coworkers investigated the line shape of the fluctuation spectrum at the polarizable water/DCE interface in the presence of the phospholipid DL-a-dipahnitoyl-phosphatidylcholine (DPPC) [32]. The line shape of experimental power spectra similar to those exemplified in Pig. 4.12 b was analyzed in terms of the mean vertical displacement of the interface generated by capillary waves. The experimental results in the presence and absence of DPPC at a wide potential range appear consistent with the description of the liquid/liquid boundary as molecularly sharjf. However it is not entirely clear from this analysis how sensitive the spectmm line shape is to the molecular organization at the liquid/Hquid boundary. As discussed in Section 4.3.2, vibrational sum frequency generation studies of the neat water/DCE interface provide a rather different conclusion. 

The spectrum of light scattered by the capillary waves is just the power... 

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