This RUI research project focuses on the investigation of low temperature collisions and energy transfer of three molecules of astrophysical interest: ammonia (NH3), carbonyl sulfide (OCS), and methanol (CH3OH). Energy-transferring collisional processes are to be measured by microwave-microwave double resonance spectroscopic techniques and pressure broadening measurements in low-temperature (10 to 40 K) samples in a cell. The studies will investigate energy transfer among low-lying rotational levels induced by collisions with helium and molecular hydrogen. The results of these studies will be used to test and refine recently calculated BH3-He/H2 and OCS-He/H2 potential energy surfaces. The broader impact of the research will involve the training of undergraduate students who will participate through summer research experiences and senior research projects. Results of the measurements will also be important to the understanding of the dynamics of ammonia, carbonyl sulfide and methanol collisions in cold interstellar molecular clouds and to an analysis of recent observations of ammonia and carbonyl sulfide trapped in liquid helium droplets. The methanol studies may shed light on the mechanism for pumping certain types of interstellar methanol masers.
