Decomposition of water Raman stretching band with a combination of optimization methods

In this study, an investigation of the behaviour of stretching bands of CH and OH groups of water-ethanol solutions at alcohol concentrations ranging from 0 to 96% by volume has been performed. A new approach to decomposition of the wide structureless water Raman band into spectral components based on modern mathematical methods of solution of inverse multi-parameter problems - combination of Genetic Algorithm and the method of Generalized Reduced Gradient - has been demonstrated. Application of this approach to decomposition of Raman stretching bands of water-ethanol solutions allowed obtaining new interesting results practically without a priori information. The behaviour of resolved spectral components of Raman stretching OH band in binary mixture with rising ethanol concentration is in a good agreement with the concept of clathrate-like structure of water-ethanol solutions. The results presented in this paper confirm existence of essential structural rearrangement in water-ethanol solutions at ethanol concentrations 20-30% by volume.