Collisions and Chemistry of Super-Excited Molecules: Experiments Using the PUMP - DUMP - PROBE Technique

Modern lasers now routinely allow experiments where large populations of highly excited molecules can be prepared with perfect quantum state selection. In a sense, the laser has become the physical chemist’s synthetic tool, allowing “optical distillation” of chemical reactants in the most purified form imaginable, individual quantum states. This article describes applications from the authors’ laboratory of these methods to studies in chemical reaction dynamics. A detailed description of the PUMP, DUMP, and PROBE technique is presented with specific emphasis on the use of stimulated emission pumping in scattering experiments. Many aspects of the behavior of highly vibrationally excited molecules are presented. These topics include infrared emission, rotational energy transfer, vibrational energy transfer, super-excited molecules colliding with surfaces, and the role of highly vibrationally excited O2 in the stratosphere.