用太赫兹时域光谱技术探测天冬酰胺的低频集体吸收频谱

用太赫兹时域光谱技术研究了室温条件下的多晶天冬酰胺样品的光谱特征，得到了相应的吸收谱和折射率.这说明样品在这个波段存在光谱响应，可以用来探测分子的结构和振动情况.研究发现，天冬酰胺在实验测量有效光谱范围(0.5—2.4THz)内有两个吸收峰，一个是位于1.642—1.758THz的宽带峰，另一个是位于2.266THz的吸收峰.用密度泛函方法在B3LYP/6-31+G(d,p)基组下做了模拟计算，并对获得的频谱进行了解析，计算得到的峰位与实验结果符合较好. 关键词： 太赫兹 时域光谱技术 氨基酸 天冬酰胺

Low-frequency collective vibrational modes of asparagine by terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy has been used to measure the spectral properties of polycrystalline asparagines at room temperature. The absorption spectra and the indexes of refraction are obtained. This result shows the sample has the spectral response in terahertz spectral range and the fact demonstrates the terahertz spectra of asparagine could be used to study the molecular structure and vibration of sample. Two absorption peaks, the broad band ranged from 1.642 to 1.758THz and the narrow one located at 2.266THz, are observed in the frequency range 0.5—2.4THz. The assignments of vibrational modes in this spectral region are made using density functional theory at the level of B3LYP/6-31+G(d,p). The theoretical results agree well with the experimental data.