Fluctuations in the unimolecular decomposition of jet-cooled NO2: Implications for overlapping resonances and the transition state

Abstract

We report a detailed examination of fluctuations in the internal state distributions of the NO (2II) fragment formed in the monoenergetic unimolecular decomposition of jet-cooled NO2, utilizing photofragment yield (PHOFRY) spectroscopy. The NO(v,J,Ω,Λ) PHOFRY spectra at E°<3000 cm−1 are highly structured, and we examine correlations among these spectra on the basis of the angular momentum, spin–orbit, parity, and vibrational labels of the monitored NO rovibrational levels. We find that levels of similar total angular momentum in the same vibrational manifold are more strongly correlated with specific resonances in the activated molecule, as well as levels of the same N in the two spin–orbit states of NO. The observed PHOFRY correlations, as well as those found in the NO(2ΠΩ; Ω=1/2,3/2) rotational state distributions, are interpreted in terms of projections of coherently excited overlapping molecular eigenstates onto the manifold of final states via levels of the transition state. The implications of the results to the transition state and the adiabatic evolution of the NO degrees of freedom are discussed.