固相果糖的太赫兹及红外特征吸收谱研究

果糖是一种常见于蜂蜜和多种植物中的简单酮糖，属于三种可食用单糖之一，可与葡萄糖结合形成双糖蔗糖。纯净的果糖常温呈白色晶体状，具有甜度高、升糖指数低等优点，广泛应用于食品行业。截止目前，由于针对固相果糖的太赫兹和红外特征吸收谱研究大多局限于单纯的实验测试或者基于单分子理论计算，缺乏较为系统完善的研究，因此从理论和实验上系统研究了固相果糖的太赫兹特征吸收谱及红外特征吸收谱，首次报道了固相果糖在频谱大于3.0 THz以外的特征吸收峰的实验值，采用基于单分子的MP2和B3LYP泛函以及基于晶胞的PBE和PW91交换相关泛函计算获得了固相果糖太赫兹及红外特征吸收谱，并与实验获得的固相果糖太赫兹及红外特征吸收谱进行了比对分析，发现基于晶胞的PBE和PW91交换相关泛函计算结果与实验获得的果糖太赫兹特征吸收峰更相符，表明固相果糖在0.1～4.0 THz的大多数太赫兹特征吸收峰源自分子间相互作用而非分子内相互作用，揭示了果糖分子周围环境对果糖振动模式的显著影响。

Study on Terahertz and Infrared Characteristic Absorption Spectra of Solid-State Fructose

As a simple ketonic monosaccharide, fructose can be found in honey and many plants. Along with glucose and galactose, fructose is one of the three dietary monosaccharides and is usually bonded to glucose to form the disaccharide sucrose. Pure fructose is white crystal at room temperature and has been widely used in the food industry due to its high sweetness and low glycemic index. So far, studies on terahertz (THz) and infrared (IR) characteristics absorption spectra of the solid-state fructose are mostly confined to the simple measurement or theoretical calculation based on isolated-molecules calculation. Therefore, the THz spectra and IR spectra of solid-state fructose have been studied theoretically and experimentally in this paper. We reported the experimental absorption features of solid-state fructose beyond 3.0 THz for the first time to our knowledge. To reproduce the measured THz spectra and IR spectra of solid-state fructose, the theoretical calculations, such as MP2 and B3LYP based on isolated-molecules as well as PBE and PW91 based on unit cells, have been carried out, respectively. The calculated results showed that the PBE and PW91 calculations based on unit cells achieve better reproduction of absorption spectra of solid-state fructose than the MP2 and B3LYP calculations based on isolated-molecules, indicating the stronger influence of the intermolecular interactions for solid-state fructose compared to the intramolecular interactions for solid-state fructose, which reveals the significant effect of the surrounding environment on the vibration modes of solid-state fructose.