Pronounced site preference and mixed dinuclear dichalcogenide anions (SSe)2− in ternary lanthanum sulfide selenides – The solid solution LaS1.9–LaSe1.9

Ternary lanthanum sulfide selenides LaS_1.9−xSe_x (0 < x < 1.9) were obtained by reaction of the elements in a potassium bromide flux. The ternary compounds adopt the CeSe_1.9 structure type (tetragonal, space group P4₂/n, No. 86) and form a complete solid solution series without indications of ordered superstructures. The lattice parameters of the samples follow Vegard’s rule and are found in the range of 915 ≤ a ≤ 943 pm and 1644 ≤ c ≤ 1703 pm. A pronounced ordering of the distribution of chalcogen atoms is observed which can be attributed to charge density and size effects. The existence of three different types of dichalcogenide anions, namely ${\mathrm{S}}_2^{2-}$, $\mathrm{S}{\mathrm{e}}_2^{2-}$ and mixed (SSe)²⁻, is evidenced by Raman spectroscopy.     

Behavior of Lβ2 visible satellites in gold around L1 threshold

The Au $L{\beta }_2$ visible satellites, $L{\beta }_2^{\prime }$ and $L{\beta }_2^{″}$ were measured around the $L_1$ absorption edge using a high-resolution Johann-type spectrometer at BL15XU, SPring-8. The relative intensities of the $L{\beta }_2^{\prime }$ and $L{\beta }_2^{″}$ satellites to that of the $L{\beta }_2$ line exhibit an abrupt jump at the $L_1$ threshold. The results suggest that the origin of the $L{\beta }_2$ satellites is mainly the $L_1$–$L_3{M}_{4,5}$ Coster–Kronig transitions.