THERMODYNAMIC PROPERTIES AND GEOCHEMISTRY OF ISOTOPIC COMPOUNDS OF SELENIUM

Abstract
Using "normal vibration equations" and statistical mechanics, the isotopic vibrational frequencies and the partition function ratios for various Se76- and Se82-containing compounds have been calculated. The equilibrium constants for selenium isotope exchange reactions derived from these partition function ratios indicate that noticeable fractionation of selenium isotopes can be expected in the laboratory and in naturally occurring processes.The Se82/Se76 ratios for 16 natural samples have been compared mass spectrometrically. Variations of up to 1.5% found in this ratio are discussed.A kinetic isotope effect of 1.5% found in a chemical reduction of selenite ion to elemental selenium is also discussed.