Detection of the contribution of harmonics to the diffracted X-ray intensity

The appreciable differences between the absorption coefficients of a foil for the characteristic radiation and its harmonics can be utilized to determine the wavelength composition of X-rays diffracted by a monochromator or sample. A simple experimental procedure is proposed and used to determine the intensity of the λ/2 harmonic diffracted by the 400 reflection of gallium phosphide at the 200 position of the molybdenum Kα peak. At a tube voltage of 45 kV the λ/2 contribution was found to be 9%; it decreased to 2.5% when pulse-height discrimination blocked 10% of the total counts. Our procedure provides a direct check of the effectiveness of balanced filters and electronic discrimination against harmonic radiation.