Dependence of XRF intensity on the tilt of the propagation plane: Experimental

The geometrical properties of the x-ray fluorescence (XRF) intensity related to the alpha-parameterization were confirmed experimentally. A special sample stage was built to allow the rotation of the sample with the propagation plane (the plane defined by the incident and take-off beam directions) and was coupled to an energy-dispersive spectrometer. The device and the way in which it was carefully aligned with the collimated x-ray beams are described. The fluorescence spectra of three NBS standard samples were measured for 16 different positions of the alpha-angle. The incident and take-off angles were both 45-degrees for sample rotations between-alpha = 0 and the maximum angle of 86-degrees. XRF intensities from non-enhanced lines do not show any dependence on alpha as predicted by theory. Enhanced lines, on the contrary, decrease in intensity when alpha-increases, allowing the isolation of the primary emission by extrapolation to the limiting case-alpha = pi/2.