DIRECT DETERMINATION METHOD FOR HOMOGENEOUS SOLID SAMPLES IN X-RAY-FLUORESCENCE ANALYSIS

The concept and theory of a direct determination method (DD method) an d the procedure for carrying out the DD method for homogeneous solid s amples are presented. The theory presented is general for homogeneous solid samples. A thin-film sample, single layer on a substrate, coatin g multi-layer on a substrate and bulk sample (including pieces, powder and fragments) can be regarded as special cases of the application of the theory. A practical application to 12 commercial iron-based spray powder samples was studied and experimental data from literature were used to calculate the composition and thickness of thin-him samples w ith the DD method. The analytical expressions of intensities of de Bee r and Brouwer were modified and applied to the DD method. Two independ ent computer programs, written in BASIC, were used to calculate the nu merical values for bulk and thin-film samples. It is reasonable to exp ect that a common computer program for the DD method will soon be deve loped and will be applied to all sorts of homogeneous solid samples wi thout specific sample preparation.