Experimental x-ray-production cross sections for the $M_3, M_4$, and $M_5$ subshells of Pt and Au by electron impact

X-ray-production cross sections for $M_3, M_4$, and $M_5$ subshells of Pt and Au by electron impact were experimentally determined at incident energies ranging between 2.8 and 28 keV. To this purpose, Pt and Au thick targets were irradiated by an electron beam in a field-emission-gun scanning electron microscope, and the x-ray-emission spectra were recorded with an energy-dispersive spectrometer. The x-ray-production cross sections were obtained as a result of the spectral processing performed through a careful parameter optimization routine previously developed, which involves an analytical function for the prediction of the experimental spectra, on the basis of ionization depth distribution functions. The results are compared with the scarce data available in the literature.

Figure 1

X-ray spectrum of Pt irradiated with 10 keV electrons. (a) Whole experimental spectrum showing platinum $M$ and $N$ lines and the carbon-$K\alpha$ peak corresponding to the conductive coating. (b) Detailed view of the$M\alpha , M\beta$, and$M\gamma$ peaks along with the obtained fit. Dots, experimental data; solid black line, fit; dotted lines, individual contribution of diagram transitions; solid gray lines, $S_1$ and $S_2$ sum peaks (see text). The inset shows a magnified view of the $M\gamma$ region.

Figure 2

Energy distribution of 3.83-keV electrons after crossing a carbon foil of 62.5 nm. The dashed lines indicate the $E_3, E_4$, and $E_5$ absorption edges of Pt. The effective energy $E_o^4$ corresponding to the Pt $M_4$ subshell and the number of electrons $N_4$ reaching the target with energy above the $E_4$ absorption edge are also shown.

Figure 3

Platinum x-ray-production cross sections: (a) $M_3$ subshell, (b) $M_4$ subshell, and (c) $M_5$ subshell. Solid spheres represent the present data. The gray lines delimitate regions where results for ${\sigma }^x$ derived from theoretical or empirical data for ionization cross sections $\sigma$ can be obtained when different combinations of relaxation parameters are used. Solid lines are data obtained from Bote and Salvat [45], and dashed lines are data from Casnati et al. [46].

Figure 4

Gold x-ray-production cross sections: (a) $M_3$ subshell, (b) $M_4$ subshell, and (c) $M_5$ subshell. Solid spheres represent the present data. Empty circles represent the experimental data from Merlet et al. [9]. The gray lines delimitate regions where results for ${\sigma }^x$ derived from theoretical or empirical data for ionization cross sections $\sigma$ can be obtained when different combinations of relaxation parameters are used. Solid lines represent data obtained from Bote and Salvat [45], and dashed lines represent data from Casnati et al [46].