A Σ+↮Σ− selection rule for the collisions of some atomic ions with diatomic molecules

✍ Scribed by David E. Parry

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 144 KB
• Volume: 74
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1999)74:2<103::aid-qua7>3.0.co;2-4

✦ Synopsis

A theoretical analysis is presented of the conservation of electronic reflection symmetry for all nuclear configurations of a system consisting of a proton, or other atomic ion having zero electronic orbital angular momentum, interacting with a diatomic molecule. Transitions between ⌺ q and ⌺ y states of the molecule are associated with a change in the parity of the system under reflection of the electronic coordinates in the plane of the three nuclei, which is shown to be forbidden in collisions to which the Born᎐Oppenheimer approximation may be applied. This selection rule is consistent with the absence of ⌺ q l ⌺ y excitations noted in recent high-resolution studies of the collisions of protons with diatomic molecules. Its extension to the double-and tripleionization of diatomic molecules in electron-transfer collisions with suitable atomic projectile ions is examined and the case of a target linear molecule with more than two nuclei also explored.