Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice, Poland.
J Phys Chem B. 2013 Apr 11;117(14):3867-76. doi: 10.1021/jp400662w. Epub 2013 Apr 1.
Acoustic properties of three (1-ethyl-, 1-butyl-, and 1-octyl-) 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide room-temperature ionic liquids are reported and discussed. The speeds of sound in RTILs were measured as a function of temperature in the range 288-323 K by means of a sing around method. The densities and isobaric heat capacities were determined from 288.15 to 363.15 K and from 293.15 to 323.15 K, respectively. The related properties, like isentropic and isothermal compressibilities, isobaric coefficients of thermal expansion, molar isochoric heat capacities, and internal pressures, were calculated. It was found that for some ionic liquids, temperature dependence of isobaric coefficients of thermal expansion is small and negative. All investigations were completed by the ultrasound absorption coefficient measurements in 1-ethyl- and 1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide as a function of frequency from 10 to 300 MHz at temperatures 293.15-298.15 K. The ultrasound absorption spectra indicate relaxation frequencies in the megahertz range.
报道并讨论了三种（1-乙基-、1-丁基-和 1-辛基-）1-烷基-3-甲基咪唑双（三氟甲基磺酰基）亚胺室温离子液体的声学性质。通过单次回波法，在 288-323 K 的温度范围内测量了 RTILs 的声速。密度和等压热容分别在 288.15 至 363.15 K 和 293.15 至 323.15 K 的范围内确定。计算了相关性质，如等熵和等温压缩系数、等压热膨胀系数、摩尔等容热容和内压。结果发现，对于某些离子液体，等压热膨胀系数的温度依赖性较小且为负。所有研究均通过在 293.15-298.15 K 的温度范围内，以 10-300 MHz 的频率，对 1-乙基-和 1-辛基-3-甲基咪唑双（三氟甲基磺酰基）亚胺的超声吸收系数进行测量完成。超声吸收谱表明弛豫频率在兆赫兹范围内。
