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Smithsonian National Museum of Natural History
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Department of Mineral Sciences

Izalco Volcano

The cathodoluminesce (CL) laboratory of the Department of Mineral Sciences is equipped for cathodoluminescent imaging and spectroscopy of geologic materials. The lab is equipped with an ELM-3R Luminoscope and MacPherson .2meter scanning monochromator with Macpherson 789A controller. Images are captured using an Olympus Magnafire CCD camera. Recently, a vibration isolation table has been added for improved high magnification imaging.

A broad beam of accelerated electrons is deflected onto the surface of a polished mineral mount or rock section. Outer shell electrons in the specimen are \"excited\" and emit energy with wavelengths that correspond to visible light (as well as the UV and near IR) upon relaxation. These colors can be digitally imaged to map out the often highly detailed growth history of minerals. In addition, the precise wavelengths emitted from a sample can be obtained with the spectroscopy system. This visible light spectrum allows one to more precisely identify individual components of luminescence.

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