基于计算谱学的纳米材料结构表征及其在石墨烯氧化物中的应用

从理论上对材料结构进行表征一般是基于第一性原理电子结构计算对可能的结构模型进行能量分析, 从而得到材料的基态构型. 而经过复杂路径合成的纳米材料并不总是处于基态能量构型. 因此, 对可能的结构模型进行计算谱学模拟, 然后直接与实验谱图对比, 可以提供更为可靠的结构信息. 本文简单介绍了谱学模拟的理论背景, 以石墨烯氧化物为例展示了计算谱学在复杂纳米材料结构表征中的关键作用.

Computational Spectroscopy for Structure Characterization of Nanomaterials:a Case Study of Graphene Oxide

Nowadays, first-principles electronic structure calculations can be routinely used to analyze energetics and then to obtain the ground-state structure of a specific material. However, with complicated synthesis routes, nanomaterials are not necessarily always in their thermodynamic ground states. In such situations, computational spectroscopy provides a reliable way for structure characterization. We first briefly introduced the theoretical background of spectrum simulation, focusing on infrared(IR) spectroscopy, Raman spectroscopy, optical absorption,nuclear magnetic resonance(NMR), X-ray photoemission spectroscopy(XPS), and scanning tunneling microscopy/spectroscopy(STM/STS). Then, structure characterization of graphene oxide(GO) was used as an example to demonstrate the power of computational spectroscopy. Comparing experimental spectra with simulated data from diffe-rent candidate structures, we obtained the information about GO structure.It was unambiguously revealed that experimentally obtained GO samples are in a kinetically constrained metastable state instead of the thermodynamic ground state. Based on computational spectroscopic studies, an updated Lerf model for GO structure was proposed.