Phase behavior of propane and n-pentane aerosol particles under conditions relevant to Titan

The phase behavior of propane and n-pentane aerosols was studied under conditions relevant to Titan's atmosphere. Pure propane or n-pentane aerosols and mixed aerosols (mixed with either acetylene, carbon dioxide, or water aerosols) were generated in a bath gas cooling cell. The phase behavior of the aerosols was studied using infrared spectroscopy. Pure propane aerosols remained in a disordered phase during the timescale of the experiment, whereas n-pentane aerosols underwent a phase transition from an initially disordered phase into a crystalline phase. For the homogeneous crystallization of n-pentane aerosols in a nitrogen bath gas the surface and volume nucleation constants were found to range from 10(12) to 10(14) cm(-2) s(-1) and from 10(11) to 10(13) cm(-3) s(-1), respectively. The presence of solid acetylene, carbon dioxide, or water aerosols did not affect the phase behavior of propane aerosols but significantly accelerated the crystallization of n-pentane aerosols with acetylene aerosols acting as the most efficient crystallization nuclei. (c) 2012 Elsevier Ltd. All rights reserved.