title: Imaging nucleophilic substitution dynamics.
abstract: 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.
authors.affiliation: Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Mikosch
authors.forename: S
authors.initials: S
authors.lastname: Trippel
authors.forename: C
authors.initials: C
authors.lastname: Eichhorn
authors.forename: R
authors.initials: R
authors.lastname: Otto
authors.forename: U
authors.initials: U
authors.lastname: Lourderaj
authors.forename: J X
authors.initials: JX
authors.lastname: Zhang
authors.forename: W L
authors.initials: WL
authors.lastname: Hase
authors.forename: M
authors.initials: M
authors.lastname: Weidemüller
authors.forename: R
authors.initials: R
authors.lastname: Wester