Electron Spectroscopic Imaging

Electron spectroscopic imaging (ESI), also known as energy filtered transmission electron microscopy (EFTEM), couples an electron energy loss imaging spectrometer to a conventional transmission electron microscope to enable the direct quantitative imaging of elements within the specimen.  By coupling the spatial information provided by transmission electron microscopy with the quantitative compositional information provided by electron spectroscopic imaging, the nucleoplasm can be studied in unprecedented detail.  The example on the left shows how phosphorus (top left) and nitrogen (top right) maps can be combined to reveal the composition of the interchromatin space.  The phosphorus rich chromatin fibers and ribonucleoprotein particles appear yellow in the bottom panel, where phosphorus is false-coloured green and nitrogen is false-coloured red.  Because protein structures have relatively little phosphorus by mass but, like DNA and RNA, are rich in nitrogen, protein structures appear red in the bottom panels.  
Copyright 2007 Michael J Hendzel, Ph.D. Department of Oncology, University of Alberta