An in-situ Raman study on pristane at high pressure and ambient temperature

The CH Raman spectroscopic band (2800-3000cm^-1) of pristane was measured in a diamond anvil cell at 1.1-1532MPa and ambient temperature. Three models are used for the peak-fitting of this CH Raman band, and the linear correlations between pressure and corresponding peak positions are calculated as well. The results demonstrate that 1) the number of peaks that one chooses to fit the spectrum affects the results, which indicates that the application of the spectroscopic barometry with a function group of organic matters suffers significant limitations; and 2) the linear correlation between pressure and fitted peak positions from one-peak model is more superior than that from multiple-peak model, meanwhile the standard error of the latter is much higher than that of the former. It indicates that the Raman shift of CH band fitted with one-peak model, which could be treated as a spectroscopic barometry, is more realistic in mixture systems than the traditional strategy which uses the Raman characteristic shift of one function group.