Excited state dynamics of nitrobenzene studied by the time-resolved transient grating method

摘要

The nonradiative relaxation processes from the photoexcited nitrobenzene (NB) have been directly detected using the time-resolved transient grating (TG) method. From the heat-releasing rates of NB in heptane, a relatively short lifetime of the lowest excited singlet state (≤ 20 ps) as well as a surprisingly short lifetime of the lowest excited triplet state (～ 400 ps) are detected. By measuring the heat energies from the excited NB, the quantum yield of the triplet formation (Φ_(isc)) and the energy of the lowest excited triplet state (E_T) are found to be ≥ 0.80 and 22～27×10~3 cm~(-1). The photophysical properties of NB are also discussed.