X-ray fluorescence analysis of Ge$_{1-x}$Se$_x$, As$_{1-x}$Se$_x$, and Ge$_{1-x-y}$As$_y$Se$_x$ glasses using electronic excitation

X-ray fluorescence analysis with fluorescence excitation by an electron beam with an energy of 30 kV is applied to determine the germanium, arsenic, and selenium contents in Ge$_{1-x}$Se$_x$, As$_{1-x}$Se$_x$, and Ge$_{1-x-y}$As$_y$Se$_x$ glassy alloys. Using calibration dependences, the quantitative composition of the glasses is determined with an accuracy of $\pm$ 0.0002 for parameters $x$ and $y$ in a surface layer $\sim$ 0.1 $\mu$m deep.