Energy shifts of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>x-ray lines for different chemical compounds of Ru, Pr, and Yb

Abstract

The energy shifts of $K{\ensuremath{\alpha}}_{2}$, $K{\ensuremath{\alpha}}_{1}$, $K{\ensuremath{\beta}}_{3}$, $K{\ensuremath{\beta}}_{1}$, and $K{\ensuremath{\beta}}_{2}$ x rays were measured for the following Ru, Pr, and Yb compounds: Ru, Ru(C${\mathrm{O}}_{2}$)${\mathrm{Cl}}_{2}$, Ru${\mathrm{O}}_{2}$, [Ru${(\mathrm{N}{\mathrm{H}}_{3})}_{4}$OHCl]Cl \ifmmode\cdot\else\textperiodcentered\fi{} 2${\mathrm{H}}_{2}$O, and Ru${\mathrm{F}}_{3}$; Pr, Pr${\mathrm{C}}_{2}$, ${\mathrm{Pr}}_{2}$${\mathrm{O}}_{3}$, PrFe${\mathrm{O}}_{3}$, ${\mathrm{Pr}}_{6}$${\mathrm{O}}_{11}$, Pr${\mathrm{O}}_{2}$, CsPr${\mathrm{F}}_{5}$, and ${\mathrm{Cs}}_{2}$Pr${\mathrm{F}}_{6}$, Yb, Yb${\mathrm{F}}_{3}$, and ${\mathrm{Yb}}_{2}$${\mathrm{O}}_{3}$. The results are compared with free-ion relativistic self-consistent-field calculations. The measurements bear out the dominant role of the $4f$ electrons in energy shifts between the trivalent and tetravalent Pr and the divalent and trivalent Yb. In Yb the full free-ion value is observed, while in Pr the free-ion value appears to be attenuated by a factor of 0.4, presumably owing to covalency. In all cases the relation of the x-ray energy shift to the M\"ossbauer isomer shift is discussed.