FOCUSING MULTILAYER MIRROR ANALYZER FOR USE IN SOFT X-RAY FLUORESCENCE YIELD NEAR EDGE SPECTROSCOPY

X-RAY ABSORPTION SPECTROSCOPY (XAS) USING SYNCHROTRON RADIATION IS BEING DEVELOPED AS A UNIQUE TOOL FOR STUDY OF STRUCTURE FOR A RANGE OF MATERIALS INCLUDING MATERIALS CONTAINING LOW-Z ELEMENTS: B, C, AND N. XAS, THE FLUORESCENCE YIELD NEAR EDGE SPECTROSCOPY (FYNES) IN PARTICULAR, REQUIES A SIGNIFICANT REDUCTION IN THE RATIO OF SCATTERED TO FLUORESCENT RADIATION EMERGING FROM THE SAMPLE. UNFORTUNATELY, JUST ABOVE AN ABSORPTION EDGE THE FLUORESCENT AND ELASTICALLY SCATTERED PHOTONS HAVE SIMILAR ENERGIES AND CAN NOT BE ELECTRONICALLY DISCRIMINATED IN THE PROPORTIONAL DETECTOR. RECENT STUDIES INDICATE THAT FOR IMPROVED PHOTON COLLECTION IN FYNSE, IT IS KEY TO USE A FOCUSING MULTILAYER MIRROR ANALYZER. PHOTONS ARRIVE AT NEAR-NORMAL INCIDENCE, ARE ENERGY ANALYZED, REFLECTED, AND FOCUSED ONTO THE DETECTOR. THE MULTILAYER'S MODEST REFLECTIVITY WILL BE OFFSET BY ITS LARGE AREA, ABILITY TO CONCENTRATE FLUX AND TO DISCRIMINATE BETWEEN FLUORESCENT AND SCATTERED LIGHT. BASED UPON OUR EXPERIENCE IN DESIGN AND FABRICATION OF MULTILAYER MIRRORS, INCLUDING HIGH PERFORMANCE NORMAL INCIDENCE FOCUSING MIRRORS WITH 2D=3641A, WE BELIEVE THAT BY THE SELECTION OF OPTIMUM LAYER MATERIALS AND SPUTTERING PARAMETERS, IT IS POSSIBLE TO REACH NORMAL INCIDENCE REFLECTIVITY OF ABOUT 10% JUST ABOUT THE CKA LINE. WE ALSO BELIEVE IT IS POSSIBLE TO DESIGN A CURVED MIRROR WITH A SOLID ANGLE OF COLLECTION OF MORE THAN 10% OF THE RADIATION WITH THE MULTILAYER D-SPACING CHANGING ACROSS THE MIRROR TO MEET THE FOLLOWING CONDITION: DISINOI=CONST(0I)., WHERE DI IS THE VARIABLE D-SPACING AND 0I IS THE VARIABLE ANGLE OF INCIDENCE.