Understanding the O4,5 edge structure of actinide metals:: Electron energy-loss spectroscopy and atomic spectral calculations of Th, U, Np, Pu, Am, and Cm

Using electron energy-loss spectroscopy (EELS) and many-electron atomic spectral calculations, we examine the O(4,5) (5d -> 5f) edge structure of the ground-state alpha phase of Th, U, Np, Pu, Am, and Cm metals. Results show that (i) atomic calculations explain the trend in O(4,5) structure along the actinide series and (ii) the dipole-allowed transitions are contained within the giant resonance. Therefore, the small prepeak in the 5d -> 5f transition of Th, U, and Np should not be labeled the O(5) peak, but rather the Delta S=1 peak. In presenting the O(4,5) EELS spectra for Np, Am, and Cm, we extend the known d -> f transitions for actinide metals.