Investigation of bonding in nano-SiO2 by Si L2,3 X-ray absorption near-edge structure spectroscopy

The Si L2,3 X-ray absorption near-edge structure (XANES) can be used to probe the local structure around Si and derive electronic information of the unoccupied s- and d-like partial density of states in nano-size SiO2. We present Si L2,3-edge for three different size silicates acquired by total electron yield (TEY) at the photoemission station of Beijing Synchrotron Radiation Facility (BSRF). The Si L2,3-edge spectra are interpreted based on ab initio full multiple-scattering (MS) calculation. The Si L2,3-edge of nano-size materials has XANES similar to that of α-quartz. The similarities between the Si L2,3-edge shapes attest to a common molecular-orbital picture of their Si-O bonding and the same coordination state. However, a considerable broadening of Si L2,3-edge XANES spectra as decrease of particle size is also an indicative of polyhedral distortions.