High Spatial Resolution Chemical Imaging.
Applications in Biology, Geology and Art 

Carol Hirschmugl
Department of Physics
University of Wisconsin-Milwaukee

From the earliest experiments with optical microscopes, researchers have examined the appearance of microbes and other microscopic plants and animals; they have strived to identify the various organelles and sub-cellular structures evident, helping them to infer their biological function.  Beyond the visual appearance of these structures, a knowledge of their chemical makeup would provide great insight into how these sub-cellular structures function in a living cell.  Moreover, tracking the changes in their chemical makeup would allow scientists to understand the organism’s response to changing environmental conditions. Here, “Chemical Imaging” combines chemical specificity from mid infrared spectroscopy with imaging. Since mid-infrared optical frequencies are resonant with the vibrational frequencies of functional groups, the absorption spectrum is a “molecular fingerprint” of the material at every pixel.  Hence, it can be correlated with known material properties to extract information. IRENI is a chemically sensitive infrared microscope illuminated with a stable, broadband source and equipped with multiple, parallel detection channels will greatly expand the ability to examine such biological structures, and to track their chemical changes within minutes.  This new facility provides the opportunity to obtain chemical images with diffraction-limited resolution in minutes.
In addition to an overview of the IRENI design and implementation, first results on biological, geological and art samples will be presented.   This new microscope facility is a national facility and will soon be available for users across a wide array of disciplines (e.g. soft matter condensed physics, nanoscience, biology, chemistry, veterinary science, engineering, environmental science and geology), providing a new interdisciplinary tool to the broader scientific community.