Raman spectroscopy of solid-phase n-dodecane and methyl oleate under high pressure

Room-temperature Raman spectra of n-dodecane and methyl oleate were acquired at pressures up to 4 GPa. Both have monoalkyl chains with characteristic Raman rotamer profiles (trans and gauche conformers) along the skeletal CC bonds. The trans conformer was dominant in the high-pressure solid phase of n-dodecane. In solid methyl oleate, most of the gauche conformers transformed to the trans conformers. The all-trans dominated in the high-pressure solid phase and a triclinic subcell structure was indicated on the basis of previous vibrational spectra of n-alkanes and lipids. The solidification pressure of methyl oleate was determined against temperature up to 413 K.