Vibrational spectrum of Ar-3(+) and relative importance of linear and perpendicular isomers in its photodissociation

Abstract

The photodissociation dynamics of the argon ionized trimer Ar 3+ is revisited in the light of recent experimental results of Lepère et al. [J. Chem. Phys. 134, 194301 (2009)], which show that the fragment with little kinetic energy is always a neutral one, thus the available energy is shared by a neutral and ionic fragments as in Ar 2+. We show that these results can be interpreted as the photodissociation of the linear isomer of the system. We perform a 3D quantum computation of the vibrational spectrum of the system and study the relative populations of the linear (trimer-core) and perpendicular (dimer-core) isomers. We then show that the charge initially located on the central atom in the ground electronic state of the linear isomer migrates toward the extreme ones in the photoexcitation process such that photodissociation of the linear isomer produces a neutral central atom at rest in agreement with measured product state distributions.