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Simple, Versatile Liquid Nitrogen Cryostat for Raman Studies

Volume 46, Number 10 (Oct. 1992) Page 1590-1592

Yue, Kwok To; Feng, Zhe Chuan; Perkowitz, Sidney; Puckett, Bud


Resonance Raman studies can often benefit from decreased sample temperature. With biological samples like frozen protein solutions, the spectral peaks are significantly narrowed at liquid nitrogen temperature due to the reduced molecular motion. Lowering the temperature can also minimize protein denaturation from local heating by the exciting laser beam. Semiconductors and their superlattices are another class of materials where Raman measurements often must be made at low temperatures. For many such samples the Raman features are very weak or not observable at room temperature; some mode intensities have a strong temperature dependence, and some modes are active only at low temperature. It is significant that most, if not all, of the features can be observed at liquid nitrogen temperatures, even though published reports often use lower temperatures requiring the more expensive and cumbersome liquid helium.