Measurements of L -Auger spectra of Pu, Am, Cf, and Fm and comparison with theory

Le résumé fourni par la source

The $L$-Auger spectra of $_{94}^{239}\mathrm{Pu}$ (64 lines), $_{100}^{254}\mathrm{Fm}$ (54 lines), $_{95}^{241}\mathrm{Am}$ (41 $\mathrm{LMM}$ lines only), and $_{98}^{250}\mathrm{Cf}$ (35 $\mathrm{LMM}$ lines only) were scanned over the range 6-19 keV at high resolution (${10}^{\ensuremath{-}3}\ensuremath{\le}\frac{\ensuremath{\Delta}E}{E}\ensuremath{\le}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$) in the Argonne National Laboratory iron-free double toroidal spectrometer using thin (\ensuremath{\le}1 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$) isotopically separated radioactive sources. The observed energies of lines or line complexes agreed with Larkins's semiempirical predictions within the combined (theoretical plus experimental) standard deviations $(1\mathrm{s}.\mathrm{d}.=10\ensuremath{-}20$ eV in 10-20 keV) in 78% of the comparisons, and 19% were within 1-2 s.d. The measured intensities (relative to ${L}_{3}{M}_{4}{M}_{5}$) for Pu were compared to nonrelativistic predictions of McGuire for $Z=90$, with the relativistic predictions of Chen et al. for $Z=94$, and with a mixed system using Chen et al. for Coster-Kronig and McGuire for $L$-Auger transitions. Fm intensities (and Am and Cf qualitatively) could be compared only to relativistic theories. Relativistic predictions are clearly better for Pu, but are not, in general, satisfactory for either Pu or Fm; for all Pu and Fm lines, taken together, 58% are within 1 s.d., 30% in the range 1-2 s.d., and 12% greater than 2 s.d., with the relativistic predictions generally low except for the ${L}_{3}\mathrm{MM}$ band, which is in acceptable agreement. The ratio of the intense lines $\frac{{I}_{{L}_{2}{M}_{4}{M}_{5}}}{{I}_{{L}_{3}{M}_{4}{M}_{5}}}$ averaged for all four spectra is $(27\ifmmode\pm\else\textpm\fi{}7)%$ above the relativistic prediction. The first clearly resolved spectator vacancy satellites of Auger lines were seen in $^{241}\mathrm{Am}$ and $^{250}\mathrm{Cf}$, and Coster-Kronig coefficients were deduced from their intensities relative to the main line. Their displacements in $^{241}\mathrm{Am}$ agree with calculations of Shirley. Intermediate coupling components of some Auger lines were also first resolved and their relative intensities observed to fit the nonrelativistic calculations of Haynes. From the relative intensities of $M$- and $N$-shell internal conversion lines of the 18.249-keV transition in $^{239}\mathrm{Pu}$, an $M1$ multipolarity is assigned.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.