RUI: Closing the Gap Between Hot and Cold Collisions--Orientation, Alignment, and Velocity Effects on Associative Ionization of State-selected Atoms in a Single Beam

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This RUI research project will measure collisions between excited-state atoms with the purpose of studying molecular structure and exploring collision theory. The primary goal is to bridge the velocity gap between traditional collision studies (done at thermal, i.e., warm temperatures in gas cells) and experiments carried out in ultracold traps. The experimental procedure makes use of narrow-bandwidth diode lasers to select thin velocity components of a thermal cesium beam. Collisions between precisely controlled velocity components lead to associative ionization, where two excited atoms form a molecular bond by ejecting an electron to carry off excess energy. The narrow-bandwidth diode lasers also allow control of atomic orientation and alignment, which are important parameters in collision theory. For the case of cesium, associative ionization offers a simple, but important example of chemical bond formation, involving one-electron bonds. This simplicity makes associative ionization of cesium a good test of collision theory. Beyond evaluating theories and understanding collision processes in sub-Kelvin environments, the broader impact of this project includes enhancing the research and teaching infrastructure of Lafayette College and training future physicists destined for graduate school and employment in industry. Undergraduates are provided with practical hands-on laboratory experience by participating directly in this research. The integration of various aspects of this project into the undergraduate laboratory curriculum provides a second avenue through which students are exposed to modern laboratory techniques.