Molecular mechanics for phase transition and melting of <i>n</i>-alkanes: A spectroscopic study of molecular mobility of solid <i>n</i>-nonadecane

Abstract

n-Nonadecane shows a phase transition from orthorhombic to so called α phase near 22.8 °C and melts at 32 °C. Temperature dependence studies of infrared and Raman spectra of n-nonadecane and of selectively deuterated nonadecanes (2D2 and 10D2) allow one to obtain a detailed description of the structural changes which take place at the phase transition and melting. Experiments are interpreted on the basis of normal mode calculations. Comparison with the information available in the literature from other experiments or calculations shows that additional information are derived in this work. A model for the mechanism of phase transition is proposed.