Quantum-State Resolved Bimolecular Collisions of Velocity-Controlled OH with NO Radicals

• Published in: Science (American Association for the Advancement of Science) Vol. 338; no. 6110; pp. 1060 - 1063
• Main Authors: Kirste, Moritz, Wang, Xingan, Schewe, H. Christian, Meijer, Gerard, Liu, Kopin, van der Avoird, Ad, Janssen, Liesbeth M. C., Gubbels, Koos B., Groenenboom, Gerrit C., van de Meerakker, Sebastiaan Y. T.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 23-11-2012; The American Association for the Advancement of Science
• Subjects: Algorithms; Approximation; Atomic and molecular collision processes and interactions; Atomic and molecular physics; Atoms; Collisions; Computation; Diatomic molecules; Dynamical systems; Dynamics; Electrostatics; Energy; Exact sciences and technology; Free radicals; Hydroxyl Radical - chemistry; Inelastic scattering; Laser beams; Materials; Mathematical analysis; Mathematical models; Molecular beams; Molecular biology; Molecules; Nitric Oxide - chemistry; Physics; Quantum Mechanics; Quantum physics; Quantum Theory; Reagents; Rotational states; Scattering of atoms, molecules and ions; State-to-state scattering analyses; Static Electricity; Velocity; Inorganic compounds; Molecule-molecule collisions; Inorganic free radical; Open shell molecule; Elastic scattering; Potential surface; Hydroxyl radicals; Diatomic molecules; State to state study; Nitroxyl radicals
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1229549

Whereas atom-molecule collisions have been studied with complete quantum-state resolution, interactions between two state-selected molecules have proven much harder to probe. Here, we report the measurement of state-resolved inelastic scattering cross sections for collisions between two open-shell molecules that are both prepared in a single quantum state. Stark-decelerated hydroxyl (OH) radicals were scattered with hexapole-focused nitric oxide (NO) radicals in a crossed-beam configuration. Rotationally and spin-orbit inelastic scattering cross sections were measured on an absolute scale for collision energies between 70 and 300 cm⁻¹. These cross sections show fair agreement with quantum coupled-channels calculations using a set of coupled model potential energy surfaces based on ab initio calculations for the long-range nonadiabatic interactions and a simplistic short-range interaction. This comparison reveals the crucial role of electrostatic forces in complex molecular collision processes.