Dieter Gruen - Early Career

Early Career

Shortly after receiving the baccalaureate degree, Gruen joined the team engaged in the large-scale electromagnetic separation of uranium-235, which was a part of the Manhattan Project during the second World War.

The safe management of fission energy depends in large part on a knowledge of the chemical properties of the actinide elements, many of which are man-made. Gruen contributed seminal studies that led to a detailed elucidation of the 5f electronic structure of several of these elements, using low-temperature magnetic susceptibility and fluorescence spectroscopic techniques. In order to investigate the range and stability of the oxidation states of actinide and other transition elements in fused salt solutions, he pioneered the field of absorption spectroscopy in high-temperature liquids. A novel solution chemistry was discovered that led, for example, to an understanding, on the basis of ligand field theory, of complex ions and coordination complexes in these highly ionic liquids. The approach introduced by Gruen was fruitful not only in helping to provide a fundamental understanding of fused salt chemistry, but also in its implications for the eventual development of a homogeneous thermal breeder reactor based on fused salt solutions containing the relatively plentiful element thorium. Such a development would constitute an energy supply for the indefinite future.

Gruen went on to explore many high-temperature gaseous species by using a variety of techniques, including matrix isolation spectroscopy methods. Closed-cycle refrigerators were first introduced by him for these investigations, which gave detailed insight into guest molecule and guest atom-noble gas matrix interactions.