A study of the evaporation and condensation of n-alkane clusters and nanodroplets using quantum chemical methods

Gun'ko, V.M. and Nasiri, R. and Sazhin, Sergei (2021) A study of the evaporation and condensation of n-alkane clusters and nanodroplets using quantum chemical methods. [Data Collection]

Project Description

The evaporation rate (gamma) of n-alkane molecules in the C8–C27range from molecular clusters and nan-odroplets is analysed using the quantum chemical solvation model (SMD) and the kinetic gas theory, assuming that the system is in a state of thermodynamic equilibrium (evaporation and condensationrates are equal). The droplet size, liquid density, evaporation enthalpy and Gibbs free energy of evapora-tion are calculated at 300–640 K. The quantum chemical calculations (SMD/HF or SMD/B3LYP methodswith the 6-31G(d,p) basis set) are used to estimate changes in the Gibbs free energy during the transfer ofa molecule from a liquid medium (clusters or nanodroplets) into the gas phase. The kinetic gas theory isused to estimate the collision rate of molecules/clusters/nanodroplets in the gas phase. This rate dependson partial pressures, temperature, sizes and masses of molecules and clusters/nanodroplets. An increasein the molecular size of evaporated alkanes from octane to heptacosane results in a strong decrease inthe values of gamma. Preliminary estimates of the evaporation/condensation coefficient, based on the directanalysis of the collisions of individual molecules with molecular clusters, are presented.