Absolute photoabsorption cross sections of strontium have been measured in the energy range extending from the 5p3/2 threshold up to above the 6s threshold. The synchrotron radiation source of the Synchrotron Radiation Research Center at Hsin-Chu was used as the background continuum. Strontium vapour was confined in a heatpipe oven. The absolute column density was determined by simultaneously measuring the temperature distribution profiles and the total pressure in the heatpipe. Absolute cross sections were determined using the Beer-Lambert law. The observed spectrum was analysed using a combination of a recent extension of the jj-coupled eigenchannel R-matrix adapted to handle highly correlated levels and the phase-shifted multichannel quantum defect theory. The main features of the observed spectrum, dominated by the presence of many window-type resonances, are well reproduced and the structures are identified. The observed absorption windows result from the fact that only continua are directly excited from the ground state.
|Number of pages||14|
|Journal||Journal of Physics B: Atomic, Molecular and Optical Physics|
|State||Published - 14 Dec 1998|