This unique laser-based instrumentation will enable resonance- enhanced multiphoton ionization (REMPI) spectroscopy to be used for the first time for the mass selective in situ detection of several key reaction intermediates in high temperature combustion. REMPI techniques enable the detection of several important intermediate species that are not easily monitored by other laser-based noninstrusive methods. This instrumentation, not yet available at any other laboratory, will provide a unique opportunity for the direct monitoring of such key reaction intermediates as CH3, CH2, C2O, C2H, and HCO in high temperature flames at sub part-per-million sensitivity levels. Such methods for efficient, controlled combustion, without contamination of environment from harmful by-products, are urgently needed to meet increasing demands for energy and for the safe disposal of hazardous wastes.