We present here the angular distribution of the radiation propagated inside MultiChannel Plates with micro-channels of ∼ 3 μ m diameter. The spectra collected at the exit of the channels present a complex distribution with contributions that can be assigned to the fluorescence radiation, originated from the excitation of the micro-channel walls. For radiation above the absorption edge, when the monochromatic energy in the region of the Si L-edge hits the micro-channel walls with a grazing angle \theta ⩾ 5^{∘}, or at the O K-edge when\theta ⩾ 2^{∘} a fluorescence radiation is detected. Additional information associated to the fine structures of the XANES spectra detected at the exit of MCPs are also presented and discussed.