Stimulated Raman scattering (SRS) spectra of the OH stretching vibrations of pure water and 2‐nm Si quantum dots (Si QDs) water solution have been investigated under different pump laser energies. Simultaneously, we have studied the spontaneous Raman spectra of pure water and Si QDs water solution at room temperature and atmospheric pressure. The results show that SRS intensity of Si QDs water solution is an order of magnitude higher than that of pure water at the same laser energy, which indicates that Si QDs enhance the SRS intensity of water molecules. The QDs enhancement SRS mechanism is attributed to the increase of third‐order nonlinear Raman susceptibility from the electric fields induced by the exciton effect of Si QDs.
Stimulated Raman scattering (SRS) of water and a 1 M KOH–H2O solution are investigated using a Nd:YAG laser in both forward and backward directions. An obvious enhanced SRS signal is realized by dissolving KOH in liquid water. Compared with pure water, the performance improvements include the appearance of low-wavenumber Raman peaks, higher Raman intensity, an increased Raman gain, and an enhanced hydrogen bonding network. In this paper, the SRS enhancement phenomenon is explained from both the hydrogen bonding structure and the mechanism of stimulated Raman scattering. We consider it to be a very important SRS enhancement technique, which is low cost, simple, but reliable. Meanwhile, it can easily be extended to other alkali hydroxides.
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