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乙基麦芽酚是一种常见的食品添加剂。该分子可能以“平面”或“立体”两种分子构型存在。应用密度泛函理论,分别对两种可能存在的构型进行了分子模拟计算,其中“平面”构型分子的理论计算拉曼光谱与实验值高度吻合,而“立体”构型分子的理论计算拉曼光谱与实验值差异显著。表明乙基麦芽酚分子是以“平面”分子构型存在。分别通过“银胶法”和“纳米银阵列法”制备了两种用于表面增强拉曼光谱的基底。采用10-3 mol/L的乙基麦芽酚溶液进行了拉曼增强实验,其中“纳米银阵列法”制备的基底增强效果明显优于“银胶法”制备的基底。通过比较乙基麦芽酚分子原始固体光谱与增强光谱的差异发现:造成1400至1600波数段内特征振动峰发生显著频移的原因,是由于纳米银增强基底的加入导致乙基麦芽酚分子中酮基基团中碳氧双键之间的电荷密度改变而造成的,该结论确定了乙基麦芽酚分子的吸附取向。
Ethyl maltol is a common food additive. The molecule may exist as either a “planar” or a “stereogenic” molecular configuration. The density functional theory (DFT) was used to calculate the molecular structures of two possible configurations respectively. The theoretical Raman spectra of the “plane” configuration molecules are in good agreement with the experimental values, while the “three-dimensional” configurations The theoretical calculation of molecules Raman spectra and experimental values significantly different. Show that ethyl maltol molecules are “plane ” molecular configuration exists. Two kinds of substrates for surface-enhanced Raman spectroscopy were prepared by “Silver Gel Method ” and “Nano Silver Array Method ” respectively. Raman enhancement experiments were carried out using 10-3 mol / L Ethyl Maltol solution, in which the enhancement effect of substrate prepared by “nano silver array method ” was significantly better than that prepared by “silver gel method”. By comparing the differences between the original solid spectra and the enhancement spectra of ethyl maltol molecules, it is found that the reason for the significant frequency shift of the characteristic vibration peaks in the 1400-1600 wave number bands is that the addition of nanosilver reinforced substrates leads to the formation of ketones in the ethyl maltol molecules This is due to the change in the charge density between the carbon-oxygen double bonds in the radical, which confirms the adsorption orientation of the ethyl maltol molecule.