## 3 Discussion
As shown in Figure 1, the surface tension changes sharply with the additive acetone. In the acetone-rich region, the interaction between acetone and water is weakened due to the decrease of water molecules, leading to the simple  
Figure 4: Raman shift of C=O stretching bond in acetone aqueous solutions at different mole ratios. Figure 5: Raman shift of OH stretching bond in acetone aqueous solutions at different mole ratios. molecular structure in the solutions. The solution properties were mainly determined by acetone. The variation of surface tension can be expressed as a long platform, which was consistent with the previous discussion. Thus, the acetone had great influence on the molecular structure and microcosmic effect in the binary system of rich water area. The effect of the acetone on the microstructure and the transformation of hydrogen bonding patterns using the Raman peak of OH bond on the water structure been fitted into several sub-components were investigated in various structural models of aqueous solutions. Accordingly, OH bonds are often divided into multiple sub-peaks. [PERSON] et al. divided the OH bond into two sub-bands at 3424.8 cm\({}^{-1}\) and 3206 cm\({}^{-1}\) been attributable to non-H-bonded and H-bonded species, respectively. Three sub-peaks of OH bond were divided and located at 3241 cm\({}^{-1}\) for the ordered water structure (ice-like structure), 3461 cm\({}^{-1}\), 3655 cm\({}^{-1}\), respectively, which was consistent with the disordered structures (defective structures) [40]. Moreover, [PERSON] et al. [37] fitted the OH bond into five Gaussian components, which was assigned to fully or partly hydrogen bonded water structure. As so, the OH stretching band was roughly fitted into three sub-peaks, being located at 3245 cm\({}^{-1}\), 3550 cm\({}^{-1}\), 3420 cm\({}^{-1}\), respectively, namely Pekl, PekII, PekIII. The PekIwas assigned to the fully hydrogen-bonded tetrahedral water and PekII as well as PekIII were assigned to the partially hydrogen-bonded water. The peak intensity of each peak obtained was noted as I\({}_{\text{I}}\), I\({}_{\text{II}}\), I\({}_{\text{III}}\), and the relative abundance of PekI was calculated as I\({}_{\text{I}}\)/(I\({}_{\text{II}}+I_{\text{III}}\)). Figure 6 shows the relative abundance of the fully hydrogen-bonded tetrahedral structure and partially hydrogen-bonded structure in the mixture with different mole ratios. As the molar ratio increased, the relative peak intensity of PekI decreased gradually, meaning the change of the composition of the fully hydrogen-bonded structure and partially hydrogen-bonded structure in the solutions. The fully hydrogen-bonded structure is broken gradually and converted to partially hydrogen-bonded water with the acetone addition. The original stable microstructure in the aqueous solutions was broken and the water molecules and acetone molecules formed a new type molecular structure through hydrogen bonding. As the content of acetone rise continuously, the molecular structure in the binary system changes gradually. Importantly, the total hydrogen bond water decreased gradually, and the relative content of hydrogen bond water reached a level of stability. Furthermore, a plurality of water molecules been surrounded by acetone molecules form a cluster structure with the increasing molar ratio, which was non-uniform microscopically and uniform macroscopically. The interaction between acetone and water can be expressed by the change of the relative content of two hydrogen bond structures. It is agreement with the change of surface tension with the molar ratio very well. It can be confirmed that the change of surface tension were associated with intermolecular interactions in solutions systems. Figure 6: Relative abundance of OH sub-bond in acetone aqueous solutions with different mole ratios.