DOUBLE-ELECTRON EXCITATION CHANNELS AT THE L EDGES OF ATOMIC HG

X-ray-absorption measurements at the L3, L2, and L1 edges of Hg vapor have been performed using synchrotron radiation. The onset of multiele ctron excitation channels involving 2p (or 2s) and 4f electrons has be en revealed. The experimental onset energies are compared with self-co nsistent-field Dirac-Fock (SCF-DF) calculations and Z+1 estimates, whi ch, in this specific case, were inaccurate. The importance of these fe atures in x-ray-absorption fine-structure structural data analysis for sixth-period elements is addressed, and the SCF-DF onset energies, co vering the elements Hf-Rn, are presented.