ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
A spectroscopic investigation of O2 isolated in D2 matrices is reported. Standard matrix isolation methods lead to only a small observable concentration of isolated molecules in D2 and fail in the case of H2. Both resonant excitation of the molecule over the A′(3Δu)←X(3Σ−g) transition, and dissociative pumping at 193 nm, lead to vibrationally relaxed A′→X emission, with a lifetime of 5.4 μs. Independent of the initial Ω component accessed, the fluorescence is polarized with a polarization ratio of 1.25±0.05; indicating that O2 does not rotate and that the transition gains its intensity by crystal field induced mixing between the 3Δu and a nearby 3Πu state. This uniquely identifies the anisotropy of the local field as Y43+Y4−3, which in turn implies that the molecule is trapped in an fcc site with its axis aligned along the [111] direction. The observed zero phonon line intensities can be explained consistently if the spin-orbit multiplet is assumed to be normal, in contrast with the accepted scheme in the gas phase. The zero phonon lines of O2 isolated in D2, show librational satellites with a 15 cm−1 spacing in the A′ state, and ∼25 cm−1 spacing in the X state. Intensity analysis of these progressions leads to the conclusion that the molecular axis in the excited state is tilted relative to the ground state. Deposits in D2 and H2 samples overcoated with Xe, after annealing, exhibited spectra of isolated O2 which are perturbed by the Xe film. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.470668
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