Electronic state and vibrational levels responsible for the decomposition

5 ELECTRONIC STATES AND VIBRATIONAL LEVELS RESPONSIBLE FOR THE DECOMPOSITION 

On the basis that 0i is strongly dependent on temperature while is practically independent, Noyes et came to the conclusion that steps I and II originate from the triplet and the excited singlet states, respectively. 

Let us first consider the question of the mechanism from the point of view of the existing hypotheses. On the basis of the concerted mechanism we have no a priori reason to favour either the triplet or the excited singlet state as the likely source of the primary reactions, however, if the biradical mechanism is valid for primary steps II and III, then the triplet state is expected to be the precursor of these reactions. 

As regards the role of the excited states responsible for the primary processes, direct experimental evidence may be obtained from the investigations carried out in the presence of quencher molecules. 

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Electronic state and vibrational levels responsible for the decomposition... 

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