Photodissociation spectroscopy of Mg + 2

Abstract

Mg +CO 2 ion—molecule complexes are produced in a pulsed supersonic nozzle cluster source. These weakly bound complexes are mass-selected and studied with laser photodissociation spectroscopy in a reflectron time-of-flight mass spectrometer system. An electronic transition assigned as 2Π←X 2Σ + is observed with an origin at 29625 cm −1 (vac). The spectrum is characterized by a six-member progression in the metal—CO 2 stretching mode with a frequency (ω′ e) of 381.8 cm −1. An extrapolation of this progression fixes the excited state dissociation energy (D′ 0) at 11194 cm −1. The corresponding ground state value (D″ 0) is 5150 cm −1 (14.7 kcal/mol). The 2Π 1 2 , 3 2 spin—orbit splitting is 56 cm −1. These studies were guided by ab initio calculations by Bauschlicher and co-workers, which provide accurate predictions of the electronic transition energy, vibrational constants and dissociation energy.