Dr. Barker at the University of Michigan will conduct a laboratory research program to investigate the properties of polycyclic aromatic hydrocarbons (PAH). In particular, the experiments will be designed to investigate the production of infrared emission from PAH molecules which are excited by the absorption of visible and ultraviolet light. In the last few years, infrared astronomical observations have shown that many celestial objects exhibit a distinctive set of emission features which have become known as the unidentified infrared emission bands. It has been suggested that these emission bands are due to polycyclic aromatic hydrocarbon-like species in interstellar space. If this is true, then PAH's could be an abundant and very important constituent of the interstellar medium. Much laboratory work remains to be done to understand the properties of PAH's before they can be confirmed to be the sources of the observed infrared emission bands. Dr. Barker's research is an important component of the Earth-based laboratory effort.
