Infrared and microwave dielectric relaxation of benzonitrile, acetonitrile and their mixtures with carbon tetrachloride at 25 C

Infrared refractive indices at B N 300 cm-I (f = 9OOO GHz) and P N 400 cm-I (f = 12 OOO GHz) and complex permitthitiese* = t' - Jd' at 3 = 300 cm-' and Y Y 400 cm-I for acetonitrile and acetonitrile-carbon tetrachloride as well as benzonitrileand benzonitrile-carbon tetrachloride mixtures at B N 125 cm-' (3750 GHz) at 25 OC are reported. Microwave complexpermittivities e*, in the frequency range -0.4-90 GHz for the same systems at 25 O C , are also reported. Visible refractiveindices at X = 589.3 nm (the sodium D line) for benzonitrile and benzonitrile-xrbon tetrachloride mixtures and for acetonitrileand acetonitrile-carbon tetrachloride mixtures and static dielectric permittivities for the same systems at 25 OC are reported.The observed dielectric relaxation processes at microwave frequencies up to 13.8 GHz for pure benzonitrile and up to 80GHz for acetonitrile can be described by a single Debye relaxation function, using a parameter e,. This value is larger thanthe figure for nIR2 at P = 125 cm-I for pure benzonitrile. For pure benzonitrile, an almost complete profile of d = d wwavenumber 3 has been determined up to the visible. For the mixtures, a single Debye relaxation function can describe themicrowave dielectric data by using a parameter e,. The latter becomes practically equal to nn2, within experimental error,for mixtures of composition XwsN I 0.10 and XCH,CIN 0 .05, respectively. Potential applications of t, (or nIR2)d ata inevaluating the longitudinal relaxation times rL and the short-range structural relaxation time rG in femtosecond-picdmolecular dynamics studies of solvation and the need for a better understanding of the dielectric properties of mixed liquidsin the development of supercapacitors are both noted.