Fluorescent X-ray transport in microchannel plates

The X-ray absorption spectra of microchannel plates have been measured at grazing incidence of the primary radiation. The Si L components of X-ray absorption near-edge structure (XANES) spectra exhibit specific features for incident angles below a certain critical value. In order to explain the experimental data, a mechanism of selective X-ray fluorescence transport via microchannels is proposed, which is based on the notion of anomalous dispersion in the vicinity of the Si L absorption edge.