Hydrogen bonding switched symmetric and anti-symmetric vibrations SRS of –CH2 in aqueous DEG solution

Abstract

The symmetric and anti-symmetric stretching vibrations of C–H extensively exist in organic molecules, which constantly arise together in Raman spectroscopy. In this study, a method was presented to switch stimulated Raman scattering peak from symmetric vibrations (2870 cm−1) to anti-symmetric vibrations (2924 cm−1) of –CH2 by regulating the hydrogen bonding (HB) associated through intermolecular and intramolecular in diethylene glycol (DEG) molecules. Such dominant association structure can be converted from DEG-DEG to DEG-H2O in the aqueous DEG solutions. The interaction between H2O and DEG was investigated through the density functional theory calculation. The changes in intermolecular HB have effects on the intramolecular vibrational modes by the intermolecular forces and symmetry of the DEG molecule. This study has exciting potential prospect and can be extended to other mixing solutions.