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Isotope and Nuclear Division

\A>S Alamos National laboratory is o|»Tiit«'cl hy thf t.'nivi'fsily of < alifumia f«if tin- Hc|»artiin'iil nf K - nnii< r . The distribution of minerals in geological samples kelps us discern the evolution and processes involved in hydrotht'rmal systems such as the one in the Sulphur Springs area of the Jemez Mountains. Here, boiling hydrothermal waters produce a variety of microgeaehemieal environments and provide an excellent site for study. Sulphur oxidation leaches the soil. as is clearly visible in this photo. The most intensely altered rocks and soil are white to pale yellow; red tones are evident in moderately altered areas, and unaltered zones show dark This polar-perspective view of ozone levels in the brown to black. Another effect of these geoehemieal reactions atmosphere of the southern hemisphere shows the is the absence of plant life in all altered zones. springtime "hole" (black, lavender, and purple) over Antarctica. Theyellowlredlgreen crescent indicates an ozone-rich area over midlatitudes of the southern hemisphere. This map is based on data from the total ozone mapping spectrometer on board the National Aeronautics and Space Administration's Ximbus 7 satellite. Data are color coded in Dobson units, which are proportional to column abundance of ozone in the atmosphere. (Adapted from A. S. Stolarski, in Scientific1 American 2.58 #/ 1988.)

We use lasers to produce the intense light needed fitr speetrtt- scopic studies of geochemical solutions and materials. We tune lasers to a variety of wavelengths to examine different types of samples. By measuring fluorescence, absorption, or Human scattered light, we determine such characteristics as structure and concentration of the species present. The blue beam from this laser is used to pump a -dopi'ti saphire rml (glowing red at center); it protluces another beam that can be tuned throughout the near infrared sftectral rcgittn but cannot be seen. We have developed a unique instrument based on this tunable near-infrared laser to da resonance Human and laser-induced Puorescence in

Cover Located in volcanic luff on the edge of the Xevuda lest Site, Yucca Mountain is the proposed site for