Vibronic band structure in the 270–330 nm photodissociation spectrum of (CO)+2

Abstract

The photodissociation spectrum (CO)+2 →hν CO++CO has been obtained in the near UV from 270–330 nm at 300 K in a fast flow reactor. Mass selected CO+ photofragments are detected following excitation with a frequency doubled pulsed dye laser. The spectrum exhibits a long progression of predissociative vibronic bands spaced by 475±20 cm−1, in contrast to the unstructured visible spectra of other dimer cations. Preliminary ab initio SCF calculations can qualitatively explain the unusual transparency of (CO)+2 in the visible.