Dioxygen spectra and bioactivation

• Intensities of spin-forbidden transitions in electronic absorption and emission spectra of molecular oxygen are analyzed in order to understand the key mechanisms of spin-states mixing induced by spin-orbit coupling (SOC) and the ways to overcome spin prohibition for various photophysical and biochemical processes. Multireference configuration interaction calculations with SOC account are used to generalize spin-selection rules for the oxygen atmospheric and Herzberg bands in free O2 molecule and in collision complexes. Intensity enhancement of the atmospheric a1g X3 sigma g-, b1 sigma g+ X3 sigma g-, and Noxon b1 sigma g+ a1g transitions upon bimolecular collisions are compared with those for Herzberg III transitions A3u X3 sigma g-. Electric quadrupole, dipole, and magnetic approximations are used for transition probability calculations. Intensity distribution in rotational lines is also considered. With this background, we propose some simple spin-selection rules for dioxygen activation in enzymatic reactions. (c) 2013 Wiley Periodicals, Inc.

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NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

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