Purchased with a grant from the National Science Foundation

What it does: X-ray diffraction is used to determine the identity of crystalline solids based on their atomic structure.

How it works: During x-ray diffraction analysis, x-ray beams are reflected off the parallel atomic layers within a mineral over a range of diffraction angles. Because the x-ray beam has a specific wavelength, for any given 'd-spacing' (distance between adjacent atomic planes) there are only specific angles at which the exiting rays will be 'in phase' and therefore, will be picked up by the detector producing a peak on the 'diffractogram'. Just like a 'fingerprint', every mineral has its own distinct set of diffraction peaks that can be used to identify it.

Instrument Statistics: Our system uses Cu Ka radiation that has a wavelength of 1.54Å. Analyses are commonly run using a 40kV 45mA x-ray tube voltage, a 0.04° soller slit, 1° divergence and antiscatter slits, and a 1/2° (for powder) or 1/4° (for clays) receiving slit.

Related Research: This system has been used extensively to collect data for a wide variety research. Some of the major projects include:

• ILWAS - Integrated Lake Watershed Acidification Study - a study of the effects of acid deposition on three Adirondack lakes
• RILWAS - Regional Integrated Lake Watershed Acidification Study - a study of the effects of acid deposition on lakes in the Adirondacks and various other locations across the United States, Canada, and Europe
• ALBIOS - Aluminum Biogeochemstry Study - a study of the effects of aluminum on forested ecosystems
• IFS - Integrated Forest Study - an international effort to study the effects of acid deposition on forest ecosystems throughout the U.S., Canada, and Europe
• DOE study of the distribution of Cesium-137 in lake bottom sediments