CHEMICAL CONTRAST IN X-RAY MICROSCOPY AND SPATIALLY RESOLVED XANES SPECTROSCOPY OF ORGANIC SPECIMENS

The scanning transmission x-ray microscope at the National Synchrotron Light Source has been used to record x-ray absorption near-edge structure (XANES) spectra from 0.01-square-micrometer regions of organic specimens. The spectral features observed reflect the molecular structure of the dominant absorbing atoms and provide the contrast mechanism for high-resolution imaging with chemical sensitivity. This technique was used with x-ray energies near the carbon K absorption edge to identify and map separate phases in various polymer blends and to map the DNA distribution in chromosomes with a spatial resolution of 55 nanometers.