X-ray absorption in atomic iodine in the K-edge region

X-ray atomic absorption of iodine in the energy region of the K edge is determined from the absorption of iodine vapor at temperatures up to 1000 degrees C with appreciable dissociation of the molecular species. Kinetics of dissociation, relevant for isolation of the absorption of the atomic species, is discussed. The atomic signal is obtained as a linear combination of the highest-temperature absorption spectra at two vapor densities; the coefficients of the combination are determined from extended x-ray absorption fine structure (EXAFS) analysis of the molecular signal. Photoexcitation channels are identified in the K-edge profile and in the spectral features originating from multielectron excitations. The applicability of the atomic absorption as the true absorption background for EXAFS analysis is demonstrated.