The Fundamental Frequencies of Certain Halomethanes. II. The Raman Spectrum of Fluoroform

Abstract

The Raman spectrum of CHF3 has been determined and the assignment to the six fundamentals has been made by considering the intensities and by comparison with the other haloforms. Checks have been obtained by two independent methods based on the theory of small vibrations. The fundamentals in CHClF2 have been revised to harmonize with the data of CHF3 and they have been empirically correlated in several spectral sequences. Molar heat capacities have been calculated for CHF3, CHClF2, and CHCl2F in the range T=250°K to T=650°K and compared with experimental values where available. The heat capacities have been fitted to empirical equations and a term added to correct to finite pressures by means of the modified Berthelot equation of state. It has been shown that these equations are accurate to 5 percent and are far more reliable than the small amount of thermal data available at present.