2008/01/10 by Jochen Mikosch, Sebastian Trippel, Christoph Eichhorn +6 · 4 citations
Physics and Astronomy · Chemistry · #Advanced Chemical Physics Studies #Mass Spectrometry Techniques and Applications #Laser-Matter Interactions and Applications
paper · doi:10.1126/science.1150238
openalex publication_date 2008/01/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Anion-molecule nucleophilic substitution (S(N)2) reactions are known for their rich reaction dynamics, caused by a complex potential energy surface with a submerged barrier and by weak coupling of the relevant rotational-vibrational quantum states. The dynamics of the S(N)2 reaction of Cl- + CH3I were uncovered in detail by using crossed molecular beam imaging. As a function of the collision energy, the transition from a complex-mediated reaction mechanism to direct backward scattering of the I- product was observed experimentally. Chemical dynamics calculations were performed that explain the observed energy transfer and reveal an indirect roundabout reaction mechanism involving CH3 rotation.