Solvent effects ultrasonic absorption

Main-group Ions.—The ultrasonic absorption of magnesium sulphate has been measured in a solvent of 37% by weight dioxan-water and the results have been discussed in the context of previous ultrasonic work with the sulphates of Mg + and Mn +. The importance of specific solvent effects in the formation of... 

Further ultrasonic absorption data have been reported on aqueous solutions of the nitrates and sulphates of four of the lanthanides, but the nature of the overall complexation mechanism remains uncertain. It appears that the deuterium isotope effect observed when DgO is substituted for HgO as the solvent is not a function of the solvated cation alone, but rather of the cation-ligand complex. 

The absorption of ultrasonic energy is also influenced by relaxation effects. At the frequencies of near 100 MHz that are employed, the relaxation times are of the order of ns, rather than the ps for dielectric relaxation. The relevant quantity is the absorption coefficient, a, divided by the square of the frequency, f2. Values of a//2 in 10-15 s2 nr1 have been measured for many solvents near 25 °C at the frequency of 104 to 107 MHz (Heasall and Lamb 1956 Krebs and Lamb 1958) and are shown in Table 3.10, being considered accurate within 2%. For a few solvents the ratio a//2 depends strongly on the frequency as it decreases somewhat for all solvents, e g., for carbon disulfide a//2/ (10-15 s2 nr1) = 2068 at 104 MHz and 776 at 189 MHz and for dichloromethane it decreases from 779 at 107 MHz to 550 at 193 MHz... 

Microanalysis Specimens for microanalysis were prepared by dispersing the powder ultrasonically in ethanol, placing a drop of this suspension on a thin carbon support film, and allowing the solvent to evaporate. X-ray absorption effects are negligible for particles on the order of O.lum thick allowing analysis of these particles without absorption corrections. For... 

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