(746d) Thermodynamics in Reduced Dimensionalities

Major qualitative differences in thermodynamic behavior are found between 3-, 2- and 1-dimensional differences, and are a result of the much smaller phase space available in systems of reduced dimensionality. Notable are the much smaller entropy and coordination numbers, and much larger fluctuations in thermodynamic variables (volume, density, pressure, internal energy, etc.) that are expected as dimensionality is decreased. In this work, we illustrate the qualitatively different thermodynamic behavior for various dimensionalities for materials composed of Lennard-Jones particles, for which accurate equations of state have been developed for both fluid and solid phases. Notable are the impact of dimensionality on those thermodynamic properties that are measures of fluctuations. The results from this work is expected to lead to future novel separation processes based on quasi-2D and quasi-1D systems, in which a 2D (or 1D) fluid or solid is in the presence of an external field, such as the force field on a liquid film from a solid or liquid substrate or due to confinement in a porous material. For example, the higher values of isothermal compressibility in reduced dimensionalities could find application in extraction processes, similar to supercritical extraction, but without the need for very high pressures or supercritical temperatures.