Microanalysis and imaging capabilities of synchrotron infrared microscopy

By combining the chemical specificity afforded by infrared spectroscopy with the spatial resolution of an optical microscope, infrared microspectroscopy has become a mainstay analytical tool in both academia and industry. While applications abound in a wide variety of fields including chemistry, polymer science, material science, forensic science, physics, art conservation and biology, the spatial resolution has remained limited to few tens of microns. The high brightness (about three orders of magnitude) brings about by the use of a synchrotron source compared to a thermal source, has opened widely the investigation domain, and the spatial resolution has become diffraction limited. Two types of infrared sources, from a synchrotron radiation, have been identified, giving roughly the same brightness advantage in the frequency region of interest in microscopy (2.5-40 mum). The potentiality of this analytical tool is documented in this article, in the study of individual human cells. Combining X-ray microscopy and IR microscopy on the same sample location appears of great analytical potential, and is illustrated in the case of human hair study.