We use lasers to detect and characterize a number of gas phase chemical intermediates such as free radicals and molecular ions. Small ions and radicals can be studied in ambient flames, afterglows, and discharges. To study complex organic species with high resolution, we cool these molecules to near absolute zero in a supersonic free jet expansion. Reactive species are introduced into such expansions by laser photolysis. We are studying both isolated ions and ionic clusters, the rotationally resolved spectra of free radicals like cyclopentadienyl, benzyl, and a variety of organo-metallic radicals. These investigations yield basic knowledge about the structure and reactivity of chemical intermediates and provide a means for their detection. We also apply similar laser diagnostic techniques to map the concentration of chemical intermediates in reactors producing electronic devices and diamond films. Our findings are of considerable practical importance to the chemical and electronic industries.

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