Experimental and theoretical study of the Kr $L$-shell Auger decay

The $LMM$ Auger spectra of krypton are measured using the photon energies $h\nu =1709$ eV, 1792 eV, 1950 eV, and 13 keV. This approach allows separating the contributions from the various core holes $L_1, L_2$, and $L_3$. Previously unobserved transitions are presented. Complementary theoretical work is performed allowing the assignment of the spectral features. The $L_{2,3}Y\text{−}MMY$ ($Y=M_{4,5},N_{1,2,3})$ Auger transitions of ${\mathrm{Kr}}^{2+}$ formed via Coster-Kronig Auger decay of the core holes $L_1$ and $L_2$ are also investigated. These spectra comprise about 4000 and 13 000 transitions, respectively, so that only general statements on the assignment, such as the configurations involved in the transitions, can be given.

Figure 1

Auger spectra in the energy range of 1100 to 1800 eV measured after ionization with photons of the energies (a) 1709 eV, (b) 1792 eV, (c) 1950 eV, and (d) 13 keV. Panel (a) shows the $L_3$-shell Auger decays and panel (b) the Auger decays of the $L_2$ as well as $L_3$ shells. Panels (c) and (d) show all three $L$-shell Auger decays. The structures indicated in green and labeled with $nl$ are due to overlapping photoelectron lines. In panel (c) the vertical lines labeled with the numbers 1 to 4 indicate $L_2{N}_{1,2,3}\text{−}XX{N}_{1,2,3}$ Auger decays which are discussed in the text. For reasons of presentation the spectra in (a) and (c) are averaged over three data points.

Figure 2

Experimental (data points) and theoretical (red curve through data points) data for ionization with a photon energy of 13 keV. The red and black subspectra show the contributions of the $LMM$ Auger decay of the ${\mathrm{Kr}}^{+}$ ions and the $L_{2,3}Y\text{−}XXY$ Auger decays of ${\mathrm{Kr}}^{2+}$ ions formed by Coster-Kronig decay, respectively. For the blue subspectrum showing only the $L_{1}MM$ Auger decays of ${\mathrm{Kr}}^{+}$ the intensities are multiplied by 5.

Figure 3

The $L_3{M}_{4,5}{M}_{4,5}$ (a), the $L_2{M}_{4,5}{M}_{4,5}$ (b), and the $L_1{M}_{4,5}{M}_{4,5}$ Auger transitions (c), which are aligned along the two-hole binding energy; see upper axis. The theoretical energy positions and Auger rates are indicated by the lower vertical bars and the calculated spectra of the $L_3, L_2$, and $L_1$ transitions by the blue, red, and magenta solid subspectra, respectively. The spectra also exhibit minor Auger transitions as well as photoelectron lines which are discussed in detail in the text. For reasons of presentation the experimental spectra in panels (a) and (c) are averaged over three data points.

Figure 4

The $L_3{M}_{2,3}{M}_{4,5}$ (a), the $L_2{M}_{2,3}{M}_{4,5}$ (b), and the $L_1{M}_{2,3}{M}_{4,5}$ Auger transitions (c), which are aligned along the two-hole binding energy; see upper axis. The theoretical energy positions and Auger rates are indicated by the lower vertical bars and the calculated spectra of the $L_3, L_2$, and $L_1$ transitions by the blue, red, and magenta solid subspectra, respectively. The spectra also exhibit minor Auger transitions which are discussed in the text. For reasons of presentation the experimental spectra in panels (a) and (c) are averaged over three data points.

Figure 5

The $L_3{M}_{2,3}{M}_{2,3}$ (a) and the $L_2{M}_{2,3}{M}_{2,3}$ (b) Auger transitions, which are aligned along the two-hole binding energy; see upper axis. The theoretical energy positions and Auger rates are indicated by the lower vertical bars and the calculated spectra of the $L_3$ and $L_2$ transitions by the blue and red solid subspectra, respectively. The spectrum in (b) also exhibit minor Auger transitions. For reasons of presentation the experimental spectrum in panel (a) is averaged over three data points.

Figure 6

The $L_3{M}_1{M}_{2,3}$ (a), the $L_2{M}_1{M}_{2,3}$ (b), the $L_3{M}_1{M}_{4,5}$ (c), and the $L_2{M}_1{M}_{4,5}$ (d) Auger transitions which are aligned along the two-hole binding energy; see upper axis. The theoretical energy positions and Auger rates are indicated by the lower vertical bars and the calculated spectra of the $L_3$ and $L_2$ transitions by the blue and red solid subspectra, respectively. The spectra in (b) and (d) also exhibit strong Auger transitions of the $L_3$ threshold. For reasons of presentation the experimental spectra in panels (a) and (c) are averaged over three data points.

Figure 7

Population of the different $L_{2,3}{N}_{1,2,3}$ and $L_{2,3}{M}_{4,5}$ levels of ${\mathrm{Kr}}^{2+}$ as result of the Coster-Kronig decays after (a) $L_2$ and (b) $L_3$ ionization. On the abscissa the binding energy of these states is given.

Figure 8

The data points in the upper part represent the $L_{2,3}MM$ Auger spectrum measured using $h\nu =1792$ eV. The solid red line close to the data points displays the theoretical result for this photon energy and the solid subspectrum in the middle shows the Auger decays of the $L_3{N}_{1,2,3}$ states populated via Coster-Kronig decay. The lower red and blue vertical bars indicate the energy positions and intensities of the $L_3{N}_{2,3}\text{−}XX{N}_{2,3}$ and $L_3{N}_1\text{−}XX{N}_1$ Auger transitions, respectively.

Figure 9

Upper part: The theoretical $L_{2,3}Y\text{−}XXY$ Auger decays of ${\mathrm{Kr}}^{2+}$ as a result of the Coster-Kronig Auger decays of the $L_1$ and $L_2$ holes of ${\mathrm{Kr}}^{+}$ subsequent to ionization with 13 keV photons. Lower part: The vertical bar diagrams indicate the main contributions to the spectrum separated according to the different initial states $L_{2,3}Y$ of ${\mathrm{Kr}}^{2+}$.