A method of analyzing atomic and molecular elements by a wavelength dispersive x-ray spectrometric device comprising a mirror or focussing arrangement including a multi-layer structure consisting of a plurality of layer pairs and a measuring and analysis detector, said method comprising the steps of directing a primary x-ray or electron beam onto a sample to be tested to induce fluorescence radiation which is then emitted therefrom, directing said fluorescence radiation onto said mirror or focussing structure at an angle such that said fluorescence radiation is reflected therefrom by at least one layer pair of said multi-layer structure, of which a first layer consists of one of lanthanum and the second of one of a carbon, onto a detector for the analysis of the sample.