Peter Johnsen ’15



Project Title

Velocity Controlled Molecular Beam Scattering

Presentation Link

View Peter's Presentation

Surface science plays a key role in catalytic converters, fuel cells, and even the destruction of the ozone layer. Furthering our understanding of this emerging field will increase our ability to design more energy-efficient industrial processes, improve the cost-effectiveness of fuel cells, and combat the chemical activity that occurs on atmospheric microcrystals. I spent this summer with scientists at the MPIBPC in an attempt to test the validity of the best theoretical models for energy transfer between molecules and surfaces, and to develop new theories for explaining these phenomena. We were able to scatter a beam of electronically excited carbon monoxide molecules with tunable velocity off a gold surface and detect when electrons are ejected, then calculated the efficiency of electron ejection. It is possible to change this efficiency by carefully sticking molecules onto the surface of the gold, and we were able to induce up to 770% more electron emission, giving the process an efficiency of roughly 85%. The current theories for molecule-to-surface energy transfer cannot explain this result, and the development of a new model will bring us closer to understanding complex surface-molecule interactions. My work at the MPIBPC has given me an interesting perspective on physical chemistry and I am taking additional quantum mechanics courses to further my knowledge of this field.

Internship Year


Project Category

Climate and Energy


Max Planck Institute for Biophysical Chemistry (MPIBPC), Germany


Alec Wodtke, Max Planck Institute for Biophysical Chemistry