First-Principles Approach to Extracting Chemical Information from X‑ray Absorption Near-Edge Spectra of Ga-Containing Materials

The
X-ray absorption near-edge structure (XANES) can provide uniquely
detailed information on the coordination environments of important
Ga-containing materials with unknown structures, including catalytically
active materials. In this study, the Ga K-edge XANES was simulated
using first-principles-based methods for seven molecular Ga complexes
as well β-Ga2O3, in order to explore the
chemical origins of the experimentally observed features. The theoretical
spectra were computed using FEFF, CASTEP, and StoBe, to assess the
sensitivity of the results to the computational approach. While the
XANES features depend on the Ga coordination environment, they are
also sensitive to the electronegativity of the ligands and the symmetry
at Ga. The white line position responds to changes in both the core
state (due to differential screening) and the valence “p”
states (arising from differences in ligand coordination).

X射线吸收近边结构（X-ray absorption near-edge structure, XANES）可向结构未知的重要含镓材料（包括催化活性材料）的配位环境提供独特且详尽的信息。本研究针对7种分子镓配合物与β-氧化镓（β-Ga₂O₃），采用基于第一性原理的方法模拟镓K边XANES，以探究实验观测到的谱学特征的化学起源。研究通过FEFF、CASTEP及StoBe三款程序计算理论光谱，以评估不同计算方法对结果的敏感性。结果表明，XANES谱峰特征不仅取决于镓的配位环境，同时对配体的电负性以及镓位点的对称性较为敏感。白线峰的位置会响应芯态（源于差异屏蔽效应）与价层p轨道（源于配体配位差异）的变化。