Ultrasonic absorption measurements

This technique has also been used for the well-known equilibrium (62). Sound absorption results in a perturbation of the equilibrium, such that the dissociation constant can be measured The magnitude of the absorption coefficient per wavelength at the frequency of maximum absorption can be related to the extent of dissociation of N2O4. 

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This value agrees well with the rest found in [191] but not with point (4), which was shown to be ZR = 3.1 in ultrasonic experiment [216], No such discrepancy was found for pure nitrogen. Therefore it may be attributed to the low sensitivity of ultrasonic absorption measurements when nitrogen is present at small concentration in a gas mixture. 

Fig. 4. Schematic diagram of experimental arrangement for pulsed ultrasonic absorption measurements. According to Ref. [29]...

In solution, [Co(terpy)2]2+ is also in a high-spin/low-spin equilibrium. Ultrasonic absorption measurements determined the spin equilibrium relaxation time in both water and MeOH solution to be less than 2 ns.249 Electron-donating functional groups such as methoxyl appended to the terpy ring result in a shift towards the high-spin form of the complex,250 as does replacement of one pyridyl ring with a pyrazole.251... 

This parameter derives from a special treatment of the data from ultrasonic absorption measurements. Thus, after calculation of the ultrasonic absorption coefficient, a(Np/cm), using a frequency in the 10-100 MHz range, the frequency dependency of this parameter is analysed in terms of the equation ... 

Ultrasonic relaxation spectroscopy (URS) is nothing but a special treatment of data from ultrasonic absorption measurements. Micelle dynamics involves characteristic relaxation processes, namely micelle-monomer exchange and micelle formation-breakdown. Ultrasonics can provide information about the kinetics of the latter, the fast relaxation process also, theoretical expressions for the relaxation time and relaxation strength such as those derived by Teubner [76] provide self-consistent estimates of both. 

Best fit parameters of the ultrasonic data to eq 2 for systems containing propanol, butanol and pentanol have been previously published [2,3]. Subsequently, studies were extended to include ultrasonic absorption measurements of ternary systems of DTAB-BE-water. Values of... 

Ultrasonic absorption measurements were carried out over the frequency range from 0 2 to 65 MHz. Three different techniques were used depending on the frequency ranges from 0 3 to 1.7 MHz, we used the plano-concave resonator method coupled with the optical detection techniques, from 2 to 7 MHz range we used the cylindrical resonator method and from 15 MHz to 65 MHz we used the pulse method. The details of the experimental system are described elsewhere. ... 

Figure 1 shows the results of the ultrasonic absorption measurements. The data is expressed as log(a// ) vs. log/, where/ represents the measurement frequency and or, the absorption coefficient Solid lines in Fig. 1 represent the curve fitted to the single relaxation... 

More recently, Cher has studied the reaction by ultrasonic absorption measurements and the results substantiate those of Carrington and Davidson. 

The MgS04 System An interesting example is given by the interpretation obtained from ultrasonic absorption measurements on 2-2 electrolyte systems. Eigen and Tamm (1962) proposed a three-step process, for example. 

The effects of dimethyl sulphoxide, lithium bromide, guanidinium chloride, sodium dodecyl sulphate, and urea on lysozyme have been studied using Raman spectroscopy. The spectrum observed was found to depend on the denaturant used, suggesting there is not a unique denatured state for lysozyme. An analysis of the interaction of sodium dodecyl sulphate with lysozyme has been published. A kinetic study of the denaturation and subsequent reduction of disulphide bonds in lysozyme has been made using rapid ultrasonic absorption measurements. 

P. Andreae, J.H. Joyce, 30 to 230 megacycle puls technique ftn ultrasonic absorption measurements in liquids. Brit. J. Appl. Phys. 13(9), 462-467 (1962). doi 10.1088A)508-... 

Ultrasonic absorption measurements in the temperature range 143 to 295 K were analyzed in terms of self-relaxation from the lowest-frequency mode of NF3 (V4) to rotational and translational degrees of freedom [53]. 

The existence of bimolecular proton exchange was demonstrated in aqueous solutions of some amino-acids (36, 42) and nucleotides (381, 3) through ultrasonic absorption measurements. These exchanges occur between differently ionized forms of the same amino-acid or nucleotide. With nucleotides the bimolecular exchange occurs between the secondary phosphoric acid function of the phosphate moiety and a protonatable group of the base ring, and is coupled with a fast stacking process, as well as with protolysis reactions at each of the two protonatable sites (38b,U3). 

Ultrasonic absorption measurements have clearly indicated that adenosine 3, 5 -phosphate exists in aqueous or 7M-urea solutions (pH 8.0) as a rapidly equilibrating mixture of syn and anti conformers about the iV-glycosidic bond. ... 

Many apparatuses for measuring ultrasonic absorption have been reported and the state of the art in ultrasonic absorption measurements can be found in Reference 44. Only the swept-frequency resonator and the pulse technique are still in use. The resonator consists of two parallel X-cut quartz crystal plates set at a fixed distance at the top and bottom of a cell filled with the investigated solution (Figure 2.6 top). The input transducer, driven by a swept-frequency... 

Figure 2.6 Cross sections of the cells used for ultrasonic absorption measurements by the fixed path resonance method (top) and variable path pulse method (bottom).

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