X-ray-edge studies and photoemission of Mn/sub x/Sn/sub 1-//sub x/Mo6S8

X-ray-absorption and -photoemission studies were carried out on the manganese-doped Chevrel-phase compound Mn/sub x/Sn/sub 1-//sub x/Mo6S8 for x = 0.1, where a maximum superconducting transition temperature T/sub c/ occurs. With use of synchrotron radiation and x-ray fluorescence, near-edge-absorption and extended x-ray-absorption fine-structure (EXAFS) spectra were obtained at the K edge of Mn in the doped compound. The results indicate that each manganese atom, surrounded by eight sulfur atoms, substitutes for tin at the center of a large cavity in SnMo6S8. The manganese-sulfur nearest-neighbor distance is found to be 2.02 +- 0.05 A, somewhat less than 2.26 A for Sn in SnMo6S8. The probable charge of manganese is found to be 4+ and, considering the valence-electron-charge model of charge transfer, this explains the observed maximum in T/sub c/. The photoemission experiments yield an energy distribution curve for the valence band which is in good agreement with band theory