Raman spectroscopic studies of methane-ethane mixtures as a function of pressure

Raman spectra of methane and methane-ethane mixtures (100, 85, and 49 mole % CH4) have been obtained as a function of pressure in the pressure range 0 .1 to 15.3 MPaA (MPa absolute). For these mixtures methane nu (1) (symmetri c C-H stretching) band positions are given as a function of pressure; for p ure methane they are in agreement with previous results. The new data on th e methane nu (1) band position of ethane-containing mixtures clearly depend on the kind of molecules surrounding the vibrating methane molecule. The n u (1) band position decreases with increasing pressure; the stronger the de pendency, the higher the content of ethane. The ethane nu (1) band position in the two mixtures showed the same kind of dependency, A qualitative expl anation for this behavior is attempted, relating it to changes in van der W aals-type interactions on pressure.