X-RAY ABSORPTION COEFFICIENTS OF THORIUM, URANIUM, AND PLUTONIUM. EXPERIMENTAL DETERMINATION AND THEORETICAL INTERPRETATION

The x-ray absorption coefficients of thorium, uranium, and plutonium were determined for the K alpha and K 6 wt.% Ru-U all radiations of silver, molybdenum, copper, cobalt, iron, and chromium Four absorption edges were found in the wavelength region covered. These were identified as the L/sub I/, L/sub II/, L/sub III/,M/sub I/, edges and a M/sub I/, M/sub II complex for plutonium. There is considerable disagreement between the experimental coefficients and the theoretical coefficients obtained from the Internationale Tabellen. Reasons for this discrepancy are discussed briefly. A correlation is obtained between the absorption of x-ray energy and the number of electrons in the 5f shell. Through a consideration of the atomic number, a screening constant, principal quantum numbers, and the atomic energy levels for thorium, uranium, and plutonium, the x- ray absorption coefficients of these elements were calculated. Screening constants and quantum conditions in the various equations were adjusted until, on the average, the experimental and calculated values agree within 2%. An increase in the screening constant of plutonium over that for thorium and uranium is interpreted in terms of the number of electrons occurring in the 5f shell. The change in certain quantum conditions for plutonium in comparison tomore » those for thorium and uranium is interpreted in terms of plutonium being a subtransitional point within the 5f transition series. (auth)« less