Switched symmetric vibration SRS of −CxH2 by hydrogen bonding regulating conformations of aqueous NPA solution

Molecular conformation is an important characteristic feature of chemistry and physics, which exists in organic molecules. Based on the hydrogen bonding (HB) regulating conformations, we proposed a scheme to switch the stimulated Raman scattering peak from the symmetric vibration mode of −CαH2 (2878 cm−1) to that of −CβH2 (2937 cm−1) of n-propanol (NPA) aqueous solution with a volume fraction of 0.55. The dominant association structure can be converted from NPA–NPA to NPA–H2O by the HB network between H2O and NPA, and the HB structures were investigated through density functional theory calculations. The changes in intramolecular vibrational modes have effect on the relative abundances of NPA molecules by intermolecular HBs. This study can be extended to explore other organic molecular conformations in mixing solutions.