Terahertz time-domain spectroscopy as a novel tool for crystallographic analysis in cellulose
Terahertz time-domain spectroscopy as a novel tool for crystallographic analysis in cellulose
复制标题
DOI：
10.1007/s10570-020-03508-9
复制
发表时间：
2020-10-08
期刊：
影响因子：
5.7
通讯作者：
Inagaki, Tetsuya
中科院分区：
文献类型：
--
作者：
Wang, Han;Horikawa, Yoshiki;Inagaki, Tetsuya
太赫兹（THz）辐射对晶格中的光学声子有响应；因此，太赫兹时域光谱（THz - TDS）在晶体学分析中具有潜在的用途。在这项研究中，使用THz - TDS研究了从不同来源提取的具有不同I（α）和I（β）组分比例的纤维素样品。这是首次有研究报道纤维素I（α）和I（β）在太赫兹区域的吸收系数在2太赫兹附近呈现不同的特征吸收峰。这可用于区分纤维素I的同质异形体，它们在晶体结构上存在差异。在2.11和2.38太赫兹处的吸收系数与纤维素样品的I（α）组分呈现出相当大的线性相关性。1.88 - 3.40太赫兹的吸收系数光谱进一步去趋势化，并分离为三个高斯峰。研究了这些分离峰的参数（积分强度、峰位）与由X射线衍射（XRD）图谱计算出的晶体结构值（晶面间距、晶体尺寸、结晶度指数）之间的相关性。
Terahertz (THz) radiation is responsive to optical phonons in crystal lattices; therefore, THz time-domain spectroscopy (THz-TDS) has potential utility in crystallographic analysis. In this study, THz-TDS was used to investigate cellulose samples extracted from different sources with varying ratios of I(alpha)and I(beta)fractions. This is the first study to report that the absorption coefficient in the THz region of cellulose I(alpha)and I(beta)presents different characteristic absorption peaks around 2 THz. This can be used to distinguish the cellulose I allomorph, which exhibits differences in its crystalline structure. The absorption coefficient at 2.11 and 2.38 THz showed a considerable linear correlation with the I(alpha)fraction of the cellulose samples. The absorption coefficient spectra of 1.88-3.40 THz were further detrended and separated into three Gaussian peaks. The correlations between the parameters of these separated peaks (integrated intensities, peak positions) and the crystalline structural values (d-spacing, crystalline size, crystallinity index) that calculated from the X-ray diffraction (XRD) pattern were investigated.