INFRARED AND MICROWAVE DIELECTRIC-RELAXATION OF BENZONITRILE, ACETONITRILE, AND THEIR MIXTURES WITH CARBON-TETRACHLORIDE AT 25-DEGREES-C

Infrared refractive indices at nu-BAR congruent-to 300 cm-1 (f = 9000 GHz) and nu-BAR congruent-to 400 cm-1 (f = 12000 GHz) and complex permittivities epsilon* = epsilon' - J-epsilon" at nu-BAR congruent-to 300 cm-1 and nu congruent-to 400 cm-1 for acetonitrile and acetonitrile-carbon tetrachloride as well as benzonitrile and benzonitrile-carbon tetrachloride mixtures at nu-BAR congruent-to 125 cm-1 (3750 GHz) at 25-degrees-C are reported. Microwave complex permittivities-epsilon*, in the frequency range approximately 0.4-90 GHz for the same systems at 25-degrees-C, are also reported. Visible refractive indices at lambda = 589.3 nm (the sodium D line) for benzonitrile and benzonitrile-carbon tetrachloride mixtures and for acetonitrile and acetonitrile-carbon tetrachloride mixtures and static dielectric permittivities for the same systems at 25-degrees-C are reported. The observed dielectric relaxation processes at microwave frequencies up to 13.8 GHz for pure benzonitrile and up to 80 GHz for acetonitrile can be described by a single Debye relaxation function, using a parameter-epsilon infinity. This value is larger than the figure for n(IR)2 at nu-BAR = 125 cm-1 for pure benzonitrile. For pure benzonitrile, an almost complete profile of epsilon' almost-equal-to n2 vs wavenumber nu-BAR has been determined up to the visible. For the mixtures, a single Debye relaxation function can describe the microwave dielectric data by using a parameter-epsilon infinity. The latter becomes practically equal to n(IR)2, within experimental error, for mixtures of composition X(C6H5CN) less-than-or-equal-to 0.10 and X(CH3CN) less-than-or-equal-to 0.05, respectively. Potential applications of epsilon infinity) (or n(IR2)) data in evaluating the longitudinal relaxation times-tau-L and the short-range structural relaxation time-tau-G in femtosecond-picosecond molecular dynamics studies of solvation and the need for a better understanding of the dielectric properties of mixed liquids in the development of supercapacitors are both noted.