氧化亚铁穆斯堡尔谱参数的分子轨道理论计算

A Theoretical MO Calculation of Mossbauer Spectrum Parameters for Fe_xO

测定了一种氧化亚铁样品的室温透射穆斯堡尔谱,由拟合计算得出其谱参数。该谱由对应 Fe^(2+)和Fe^(3+)离子的亚谱组成,Fe^(2+)亚谱可分解为两组四极分裂双峰;Fe^(3+)亚谱为分裂较小的双峰。选取了Fe_rO 结构的原子簇模型。用分子轨道理论计算出铁离子核位上的电子密度与电场梯度,据此算出相应的理论谱参数及其与电子结构及晶格畸变参数间的关系,从而对实验结果做出定量理论计算解释。

the Mossbauer spectra of FexO samples were measured at room temperature with their parameters obtained through fitting computation. The spectra consist of three subspectra which refer to Fe2+ and Fe3+ ions. The Fe2+ subspectrum can be fitted with two quadrupole split doudlets. The Fe3+ subspectrum is considered as a doublet with a small split. The theoretical MO calculations were performed on the cluster models selected according to the structural features of FexO,and electronic charge densities and EFG at nuclear site were thus computed. A quantitative relationship is obtained between the calculated parameters and the cluster structure distortion. It follows that the experimental Mossbauer spectrum parameters can be interpreted using the calculated results theoretically.