Ion Photofragment Spectroscopy--Potential Surfaces of Molecular Ions.

Abstract

Abstract : Techniques of ion photofragment spectroscopy have been used to investigate the structure and dissociation of molecular ions. For this research, a unique laser-ion coaxial beams spectrometer was constructed, allowing substantially improved sensitivity and resolution. The rare gas dimer ions were studied in detail, resulting in the determination of potential curves, absorption and photodissociation cross sections, and photofragment angular distributions for these ions. Effects from spin-orbit coupling were found to be very important. The predissociation of the positive and negative ozone ions were investigated to obtain structural information about these ions. Very high resolution spectroscopy of the quartet states of the positive oxygen ion allowed a substantial improvement in these potential curves, as well as an improved determination of the bond dissociation energy of neutral oxygen. Photofragment spectroscopy of the positive ion of CH led to the observation of two predissociations, one in the singlet and one in the triplet system. Similar measurements on the positive ion of methyl iodide led to the resolution of rotational and fine structure levels in the previously observed predissociation of this ion. (Author)