We will study the stability of specific chemical elements and measure the mass of certain types of biological substances and embedding materials as a function of irradiation and temperature. We will use an electron energy loss spectrometer interfaced to a computer to make quantitative measurements. While this work is going on, we will develop a more efficient data acquisition system based on new interfaces and computer programs. To measure very cold specimens, we will mount our spectrometer on a special electron microscope with a superconducting objective lens operating at liquid helium temperature. This will help future research efforts because very low temperature will probably stabilize some elements, hence improving the accuracy of concentration measurements and allowing the use of certain chemical elements as site-specific stains. We will learn which elements are "caged at low temperature or "frozen" onto surfaces. Improved stability of embedding materials will allow more accurate three-dimensional views of sectioned specimens. Studies of major classes of molecules (like DNA) will indicate which materials are most helped by low temperature. Development of new instrumentation will improve the efficiency of our studies of radiation effects and will allow our techniques to be used more widely by other.
