Field Control of Cold Molecular Collisions

ended

It is a long held dream of chemical physicists to study (and to control!) the interactions between individual molecules in completely specified collisions. This project brings this goal within reach. I will develop novel methods to study collisions between individual molecules at temperatures between 10 mK and 10 K, and to manipulate their interaction using electric and magnetic fields. Under these cold conditions, the collisions are dominated by quantum effects such as interference and tunneling. Scattering resonances occur that respond sensitively to external electric or magnetic fields, yielding the thrilling perspective to provide “control knobs” to steer the outcome of a collision. Building on my unique experience with state-of-the-art molecular beam deceleration methods, I will study scattering resonances for chemically relevant systems involving molecules such as OH, NO, NH3 and H2CO in crossed beam experiments. Using external electric or magnetic fields, we will tune the positions and widths of resonances, such that collision rates can be changed by orders of magnitude. This type of “collision engineering” will be used to induce and study hitherto unexplored quantum phenomena, such as the merging of individual resonances, and resonant energy transfer in bimolecular collisions. Measurements of exotic collision phenomena under yet unexplored conditions as proposed here provide excellent tests for quantum theories of molecular interactions, and pave the way towards the engineering of novel quantum structures, or the collective properties of interacting molecular systems. The proposed research program will transform this field from merely “probing nature” with the highest possible detail to “manipulating nature” with the highest possible level of control. It will open up a new and intellectually rich research field in chemical physics and physical chemistry, and will be a major breakthrough in the emerging research field of cold molecules.