Pressure tuning spectroscopy of the lowhyphen;frequency Raman spectrum of liquid amides

摘要

The effect of hydrostatic pressure up to 4 kbar on the low frequency Raman spectrum of hydrogen bonded (formamide,Nhyphen;methylformamide,Nhyphen;ethylformamide, andNhyphen;methylpropionamide) and nonhydrogen bonded (N,Nrsquo;hyphen;dimethylformamide andN,Nrsquo;hyphen;dimethylacetamide) liquid amides is reported. A shift of ca. 4.0 cmminus;1/kbar is observed for the nonhydrogen bonded amides. For the hydrogen bonded amides the shift is ca. 2.0ndash;3.0 cmminus;1/kbar. The difference may be explained by the compression of the hydrogen bond which affects the librational motion of the molecules.