Resonance Raman scattering from metastable O2 molecules in γ-irradiated NaClO3: Excitation profile, polarization measurements, and decay kinetics

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Abstract
Resonance Raman effects have been observed with the 1544 cm−1 O–O stretching mode of a metastable O2 species (O2*) in γ‐irradiated NaClO3. An excitation profile of the 1544 cm−1 band was determined from the scattering intensity measured with exciting lines from 457.9 to 625.6 nm, and the overtones, 2ν to 4ν, were observed with 457.9 nm excitation. Linear depolarization ratios (ρl) were measured as a function of exciting line wavelength from 457.9 to 514.5 nm. An average value of ρl∼0.42 was found from z (xz) y and z (yx) y scattering, but a pronounced dispersion was observed in ρl for z (yz) y scattering. The change in intensity of the 1544 cm−1 band observed over a period of days showed that the O2* species decays by a first order process at 300 K with a half‐life of 1.4 days. A model of O2* consisting of a weakly bound complex [X,O2], where X is a radiation produced radical or ion, is discussed.