Gofurov Shukur, Makhmanov Urol, Kokhkharov Abdulmutallib, Ismailova Oksana B
1 Institute of Ion-Plasma and Laser Technologies, Uzbekistan Academy of Sciences, Tashkent, Uzbekistan.
2 Uzbekistan-Japan Innovation Center of Youth, Tashkent State Technical University, Tashkent, Uzbekistan.
Appl Spectrosc. 2019 May;73(5):503-510. doi: 10.1177/0003702819831325. Epub 2019 Feb 20.
A refractometric method, coupled with molecular dynamics study, attenuated total reflection Fourier transform infrared (ATR FT-IR), and Raman spectroscopy, was used to determine optical characteristics of concentration features of aqueous solutions of acetic acid. Measurements of the refractive index of aqueous solutions of acetic acid in the wide range of acetic acid concentrations (∼ 0 ÷ 1 mole fraction) in a solution at a room temperature were conducted. Maximum value of refractive index was detected at a concentration of ∼0.3 mole fraction. The deviation from the parabolic form of the dependence of the refractive index on the concentration occurs at a concentration of ∼0.8 mole fraction. As far as we know, this deviation has been observed for the first time. The maximum is attributed to the largest number of molecular interactions between water and acetic acid molecules, while the deviation is associated with the parallel orientation of acetic acid molecules. To identify the reconstructing of molecules in the system, FT-IR and Raman spectra of these solutions at a concentration of ∼0.3 and ∼0.8 mole fraction were recorded and compared with pure solutions. The data obtained by using ATR FT-IR and Raman spectroscopy support the idea that the refractometric method is sensitive to determine the structural states of aqueous solutions of acetic acid.
采用折射法，并结合分子动力学研究、衰减全反射傅里叶变换红外光谱（ATR FT - IR）和拉曼光谱，来测定乙酸水溶液浓度特征的光学特性。在室温下，对乙酸水溶液在较宽的乙酸浓度范围（约0÷1摩尔分数）内的折射率进行了测量。在约0.3摩尔分数的浓度下检测到折射率的最大值。在约0.8摩尔分数的浓度时，折射率与浓度的依赖关系偏离抛物线形式。据我们所知，这种偏差是首次观察到。最大值归因于水和乙酸分子之间最大数量的分子相互作用，而偏差与乙酸分子的平行取向有关。为了确定体系中分子的重构情况，记录了这些溶液在约0.3和约0.8摩尔分数浓度下的FT - IR和拉曼光谱，并与纯溶液进行比较。使用ATR FT - IR和拉曼光谱获得的数据支持了折射法对确定乙酸水溶液结构状态敏感这一观点。
