A preliminary report is presented on experiments using fast ion-beam translational energy spectroscopy to study dissociative photodetachment and photodissociation dynamics in the small cluster ions O₄^- and O₂^-(DOT)(H₂O). Translational energy and angular distributions of coincident molecular fragments were recorded from the photodestruction of O₄^- and O₂^-(DOT)(H₂O) at 523, 349, and 262 nm. At each wavelength, the O₄^- results confirm the existence of at least two distinct channels: dissociative photodetachment (O₄^- + h(nu) yields O₂ + O₂ + e^-) and photodissociation (O₄^- + h(nu) yields O₂ + O₂^-). Observation of strongly anisotropic angular distributions shows that dissociation occurs on the time-scale of molecular rotation in both processes. The photodissociation of O₄^- at 523 nm gives a new value for the O₂-O₂^- bond energy, D_O equals 0.39 +/- 0.05 eV. In O₂^-(DOT)(H₂O), a single dissociative photodetachment channel (O₂^-(DOT)(H₂O) + h(nu) yields O₂ + H₂O + e^-) is observed at all wavelengths. Angular distributions from this process are slightly anisotropic and exhibit a small wavelength dependence.

Date Published: 18 September 1995
PDF: 12 pages
Proc. SPIE 2548, Laser Techniques for State-Selected and State-to-State Chemistry III, (18 September 1995); doi: 10.1117/12.220836

Published in SPIE Proceedings Vol. 2548:
Laser Techniques for State-Selected and State-to-State Chemistry III
John W. Hepburn, Editor(s)