Chemical Bond Effects on Line Intensities in Arsenic X-Ray Emission Spectrum

This paper offers a critical analysis of chemical bond effects using X-ray fluorescent spectroscopy based on currently available equipment. Most chemical bond effects cannot be investigated with standard X-ray fluorescent spectrometers, primarily because of low spectral resolution. Therefore, we suggest an approach based on recording the intensity ratio of the last emission line (IR LEL) of the given X-ray series to the line of an electron transition between the core levels of the same atom. Using various chemical compounds of arsenic as an example, we investigated the dependence of the intensity ratio of the As K ₂ and As K ₁ lines (IR LEL of the arsenic K-series) on various structural parameters. An experimental study points to the existence of linear dependences of IR LEL on the radius of the first coordination sphere, the covalent radius of the nearest atom, and the concentration ratio between the elements of the corresponding phase, defining the deviation from stoichiometry. Using such dependences, one can determine, using X-ray data, the bond length of arsenic in various compounds on a low-resolution spectrometer.