Affiliations: Center for X-Ray Optics, Accelerator and Fusion Research Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, California 94720 | Los Alamos National Laboratory, P-14, P.O. Box 1663, MS D410, Los Alamos, New Mexico 87545
Note: [] LBL Emeritus, 1200 Mira Mar Ave., No. 1324, Medford, OR 97504.
Note: [] U.S. Department of Commerce, National Institute of Standards and Technology, Bldg. 221 Rm. A251, Gaithersburg, MD 20899.
Note: [] Department of Physics, B-019, University of California at San Diego, La Jolla, CA 92093.
Abstract: This report describes a synthesis of more than 10 years of this program's development and application of multilayer analyzers for absolute Bragg spectrometry in the low-energy x-ray region of 50–1000 eV. Multilayers, denned here as systems of periodic layered structures parallel to the analyzer surface, have been applied principally in the diagnostics and application of the new, intense sources of synchrotron and high-temperature plasma x radiation. Detailed absolute reflectivity characterizations are presented for selected examples of these multilayers which have been semiempirically determined for mica, potassium acid phthalate, and the fabricated Langmuir-Blodgett and sputtered multilayer analyzers with d-spacings in the 10–200 Å range. Design requirements for absolute spectrometry are established. Efficient analytical multilayer reflectivity models are derived and parameterized (based upon a modification of the Darwin-Prins model for the low-energy x-ray region), including, for the sputtered multilayers, parameters for defining interface structure. The dependence of the reflectivity characteristics, high-order Bragg diffraction suppression, and overall efficiency upon the model parameters is analyzed. A special spectrograph and procedure for the absolute measurement of the relevant reflectivity characteristics are described. Detailed measurements and semiempirical characterizations are presented. Programs for small laboratory computers have been developed that allow rapid and flexible spectral analysis, transforming measured spectra to absolute Spectra.
