Ethanol - Aqueous Solution Raman Spectroscopy And Concentration-dependent Studies

In this paper, the Raman spectra of ethanol in aqueous solution were obtained by experimental testing, Focused on analysis of the spectral characteristics associated with the O-H and the C-H stretching vibration, and the correlation between the spectral and the concentration of ethanol solution.In course of the study, Raman spectral which corresponding to the O-H and the C-H stretching vibrations were intercepted separately, Followed by filtering, smoothing, subtracting baseline and other data processing, and based on the second derivative calculation and Gaussian fitting, for element analysis of Gaussian function; Also the peak value, peak position, peak area and FWHM were extracted corresponding to the three peaks of the O-H and the C-H stretching vibration. The results show that:(1) The Raman spectra of the O-H stretching vibration is superimposed by three Gaussian peaks, and with the ethanol concentration increased, the center of three Gaussian peaks are moved to higher wave number (blue shift); (2) Corresponding to the three characteristics of the C-H stretching vibration, the peak position moved to lower wave number with the ethanol concentration increased(red shift);(3) For 0 to 100% of the ethanol concentration range, the center of the second Gaussian peak for the O-H stretching vibration and ethanol concentration with a good linear relatio-nship, the linear correlation coefficient is about 0.9960;(4)For 70% to 100% of the ethanol concentration range, the center of the first Gaussian peak for the O-H stretching vibration and the ethanol concentration with linear relationship, the linear correlation coefficient is 0.9980, "Ethanol concentration-OH frequency shift relations" etc models were built, proposed the corresponding detection method of ethonal concentration;(5) With the change of ethanol concentration, the center of Gaussian peak for the O-H stretching vibration have taken place great changes, close to 80 cm-1, Based on these results establish the ethonal concentration detection method, can obtain a higher detection sensitivity and accuracy.This study also showed, for the blue shift of the O-H characteristic peaks center, show that as the ethanol concentration increased, the O-H bond force to strengthen, the O-H interatomic distance decreases, the stretching vibration frequency increases, the bond energy to increase; For the red shift of the C-H characteristic peaks center, show that with the ethanol concentr- ation increased, the C-H bond force decreases, the C-H interatomic increases, the C-H stretching vibration frequency decreases, the bond energy to reduce. These relationships, for further study the molecular structure, physical properties,chemical properties and biological effects in ethanol- water mixture, providing a valuable reference.