IPCF-CNR, UOS Roma, I-00185 Roma, Italy.
Sci Rep. 2013;3:1203. doi: 10.1038/srep01203. Epub 2013 Feb 4.
Sudden changes in the dynamical properties of a supercritical fluid model have been found as a function of pressure and temperature (T/T(c) = 2-5 and P/P(c) = 10-10(3)), striving with the notion of a single phase beyond the critical point established by thermodynamics. The sound propagation in the Terahertz frequency region reveals a sharp dynamic crossover between the gas like and the liquid like regimes along several isotherms, which involves, at sufficiently low densities, the interplay between purely acoustic waves and heat waves. Such a crossover allows one to determine a dynamic line in the phase diagram which exhibits a very tight correlation with a number of thermodynamic observables, showing that the supercritical state is remarkably more complex than thought so far.
在压力和温度的作用下（T/T(c) = 2-5 和 P/P(c) = 10-10(3)），已经发现超临界流体模型的动力学性质会发生突然变化，这与临界点之外的单相概念相矛盾，该临界点是由热力学确定的。太赫兹频率区域中的声波传播揭示了在几个等温线中，气体状和液体状之间的急剧动态交叉，在足够低的密度下，这种交叉涉及纯声波和热波之间的相互作用。这种交叉允许在相图中确定一条动态线，该线与许多热力学可观测量表现出非常紧密的相关性，表明超临界状态比迄今为止人们认为的要复杂得多。
