Isomerization and dehydrogenation of highly vibrationally excited azulene+ produced via S2 vibrational manifold

Abstract : High resolution energy-ToF correlation spectrometer and a nanosecond laser is employed to extract Hloss rate in hot azulene cations in UV region. Correlation between the photon wavelength and H-loss rate is obtained for 3-photon process and it is explained by a two-step mechanism: (i) 1+1 ionization with ultrafast internal conversion to the long-lived S2 state (ii) the increase of internal energy by absorption of the third photon and isomerization. The work uncovers the role of S2 state dynamics in Azulene in controlling the internal energy to a very narrow range.