Influence of laser-induced plasma on stimulated Raman scatting of OH stretching vibrational from water molecules

532 nm pulse beam is used to induce the stimulated Raman scatting of water molecules. Different Stocks and anti-Stocks characteristic peaks of OH stretching vibrational from water molecules are obtained when the position of the focal spot is changed. The unique ± 3400 cm-1 Stokes characteristic peak with its anti-Stokes is present when the distance between focal spot and interface is fixed to be over 20 mm; both ±3000 cm-1 and ±3400 cm-1 with their anti-Stokes exist when the distance is reduced under 20 mm; both characteristic peaks are enhanced especially the 3000 cm-1 peak whose change is more remarkable when the spot continues to move up. Experimental results indicate that laser-induced plasma generated from water molecules enhances the stimulated Raman scattering of OH stretching vibrational from water molecules by affecting hydrogen bonds between water molecules and OH from single water molecules.