As organizer of the international Workshop on Flame Chemistry series, he has been an important part of the validation efforts of chemically accurate models, and regularly hosts international collaborators. Spanning the range from ignition chemistry to the chemistry of soot and aromatic precursors, Dr. Hansen uses a highly sensitive molecular beam mass spectrometer and a tandem mass spectrometer to reveal important chemical pathways. As a facility scientist, he adapts these tools for use in plasma systems where they would provide much-needed validation of plasma chemistry reaction sets.