Vibrational scattering anisotropy in O 2 - dynamics beyond the Born-Oppenheimer approximation
2012 (English)In: New Journal of Physics, ISSN 1367-2630, Vol. 14, 113018- p.Article in journal (Refereed) Published
Bornâ€“Oppenheimer and Franckâ€“Condon approximations are two major concepts in the interpretation of electronic excitations and modeling of spectroscopic data in the gas and condensed phases. We report large variations of the anisotropy parameter ( Î² ) for the fully resolved vibrational sub-states of the X 2 Î g electronic ground state of O + 2 populated by participator resonant Auger decay following excitations of K-shell electrons into the Ïƒ â˜† resonance by monochromatic x-rays. Decay spectra for light polarization directions parallel and perpendicular to the electron detection axis recorded at four different excitation energies in the vicinity of the O1sÂ â†’Â Ïƒ â˜† transition are presented. Breakdown of the Bornâ€“Oppenheimer approximation is for the first time selectively observed for the lower vibrational sub-states, where two quantum pathsâ€”resonant and directâ€”leading to the same final cationic state exist. The higher vibrational sub-states can only be populated by resonant photoemission; hence no interference between these channels can occur.
Place, publisher, year, edition, pages
2012. Vol. 14, 113018- p.
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:uu:diva-196633DOI: 10.1088/1367-2630/14/11/113018OAI: oai:DiVA.org:uu-196633DiVA: diva2:610549