Mechanisms of Relaxation of Electronic Excitation of Triazido-S-triazine

Authors P.O. Kondratenko1 , Yu.M. Lopatkin2 , T.M. Sakun1

1National Aviation University, 1, Liubomyr Huzar ave., 03058 Kyiv, Ukraine

2Sumy State University, 2, Rymsky-Korsakov St., 40007 Sumy, Ukraine

Issue Volume 13, Year 2021, Number 5
Dates Received 16 July 2021; revised manuscript received 20 October 2021; published online 25 October 2021
Citation P.O. Kondratenko, Yu.M. Lopatkin, T.M. Sakun, J. Nano- Electron. Phys. 13 No 5, 05009 (2021)
PACS Number(s) 31.50.Df, 82.20.Wt
Keywords Relaxation of electronic excitation, Highly excited states, Dissociative potential surface, Configurational interaction, Photodissociation of azides.

The discovery of fullerenes and the identification of carbon nanotubes became a stage in the development of materials science, instrumentation, and new nanotechnology. As a result of studies of the mechanisms of electronic excitation relaxation in symmetric molecules of triazido-S-triazine, it is shown that the C3 symmetry of the molecule determines the fact that the energy levels of the excited states are treefold. Among the triplet states, the first three ππ*-states have the lowest energy, followed by three πσ*-states. Among the singlet states, the first three πσ*-states have the lowest energy. The following states are ππ*-states responsible for the UV absorption spectra of the molecule. The excitation of a molecule into these states quickly relaxes into πσ*-states from which the processes of dissociation of the molecule are possible. On the other hand, the πσ*-configuration of singlet states facilitates the rapid conversion of the molecule into triplet πσ*-states. It is shown that the configurational interaction between three local πσ*-states leads to the creation of three delocalized molecular orbitals (MO). This creates three energy levels of the excited state, the lowest of which corresponds to the MO, which has C3 symmetry. The other two MOs have reduced symmetry, and therefore they are responsible for the dissociation of the molecule. It turned out that states T5 and S3 have a dissociative potential surface. The interaction between the states causes a decrease in the quantum yield of the photodissociation of the molecule.

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