Application of Synchrotron Radiation to Microprobe Trace Element Analysis of Biological Samples.

摘要

An x-ray fluorescence microprobe (XRM) for trace element analysis is in operation at the National Synchrotron Light Source of Brookhaven National Laboratory. The properties of synchrotron radiation, in this case a continuous spectrum of x rays ranging up to 40 keV, make possible its uses as a microprobe beam with collimation or focusing with appropriate optical elements. Sensitivities in thin samples at 10 (times) 10 (mu)m(sup 2) spatial resolution is of the order of 10 fg using filtered, collimated ''white light'' and about 3 fg using a Kirkpatrick-Baez (KB) focusing system in thin standard foil. Results using a newly installed ellipsoidal mirror will be described. A discussion of standards for microprobe analysis is included. Examples of applications to the life sciences are described. These include the mapping of trace element distributions in thin tissue samples and examples of transmission and fluorescence microtomography. Synchrotron radiation microprobes complement ion and electron beam microprobes and the differences between the methods are considered. 23 figs., 4 tabs.