Creative Research Medal 2004
Uwe Happek, Associate Professor of Physics, studies dynamic processes that occur in condensed matter, an area of physics devoted to understanding materials and their properties. Condensed matter physics research drives development of new materials to run computers faster, convert sunlight into electricity efficiently or operate trains on frictionless tracks. Dr. Happek has made important contributions to understanding the underlying physics that control light-emitting efficiency in phosphor materials, widely used in fluorescent lighting, TV screens and medical imaging equipment. He has developed two new methods to determine energy levels in phosphors, which are made of rare earth or transition metal ions embedded in a “host” material. In lighting devices, UV radiation generated by a gas discharge or a UV emitting diode optically excites the ions. As the ions return to the normal state, visible light is released. The light-emitting efficiency of this process depends on the relative position of the energy levels of the ions and the host material, because some (in special cases all) of the energy is transferred to the host material, resulting in so-called quenching of the luminescence. Measuring the relative energy levels of rare earth ions and host materials has proved difficult. Dr. Happek’s new techniques will advance development of new, high-efficiency materials. He has collaborative projects with other scientists and research groups in the United States, Europe and Asia, and with industry.