In English

Abstract

The evaporation rate (g) of n -alkanes C 8 –C 27 from molecular clusters and nanodroplets 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 (i.e. evaporation and condensation rates are equal). The droplet size, liquid density, evaporation enthalpy and Gibbs free energy of evaporation are calculated over a broad temperature range of 300–640 K. The quantum chemical calculations (SMD/HF or SMD/B3LYP methods with the 6-31G(d,p) basis set) are used to estimate changes in the Gibbs free energy during the transfer of a molecule from a liquid medium (modelled by clusters or nanodroplets) into the gas phase. The kinetic gas theory is used to estimate the collision rate of molecules with clusters/nanodroplets in the gas phase. This rate depends on partial pressures of components, temperature, sizes and masses of molecules and clusters/nanodroplets. An increase in the molecular size of evaporated alkanes from octane to heptacosane results in a strong decrease in the g values.