Multilayer mirror as a substrate for total reflection X-ray fluorescence spectrometry

X-ray field intensity generated over a multilayer surface during a strong Bragg reflection condition has been used to analyze the particulate matter deposited on its surface, for the average particles size distribution and detection sensitivity of various elements. The elemental detection sensitivities achieved at Bragg reflection condition are compared to those obtained at incidence angles below critical angle, under total external reflection condition. The results obtained indicate that when big size particles (> 1 μm) are distributed over a large surface area, the observed fluorescence yields deteriorate by 15-18% in the total external reflection condition, due to strong sample absorption effects. In such a case, use of a multilayer mirror as a sample carrier and fluorescence excitation under Bragg reflection condition provides better fluorescence yield and hence improved detection sensitivity for an element.