Local electronic structure analysis by site-selective ELNES using electron channeling and first-principles calculations

In this paper, we review our recent analyses of electron energy loss near edge structure (ELNES) of particular crystalline sites, exploiting dynamical electron diffraction effects, or electron channeling, whereby the excitation weights of the Bloch waves propagating in a crystal can be controlled systematically by adjusting the diffraction conditions. A state-of-the-art data processing technique, multivariate curve resolution (MCR), can restore purely site-specific spectral profiles and their compositions from the experimental data set. Another technique, the Pixon deconvolution method, effectively removes the statistical noise, which enables us to compare the spectral fine structures with those calculated by first principles and discuss the site-specific local atomic and electronic structures. We demonstrate typical case studies in model materials and then an advanced chemical state analysis in a real material. Finally, some remarks toward further refinement of the method are made.