Thermodynamics of acetylene van der Waals dimerization

Abstract

Integrated band intensities of the 620 cm −1 absorption in (C 2H 2) 2 have been measured by FTIR spectroscopy at constant acetylene pressure between 198 and 273 K. These data, in conjunction with ab initio results for (C 2H 2) 2, have been used for the statistical evaluation of the equilibrium constant K p( T) for acetylene cluster dimerization. Present results are used to clarify the role of molecular clusters in chemical systems at or near equilibrium, in particular in Titan's stratosphere.