[Luminescence emitted from the second excited electron state (S2) of chlorophyll a]

A weak emission band at 582 nm in the spectrum of chlorophyll a in ether was observed under the 568.1 nm laser excitation. By means of the excitation spectra and using the method of fluorescence detection of triplet state this band was assigned to the radiative transition S2 leads to S0 of the chlorophyll a molecule. The evaluated value for the lifetime of the excited state S2 is about 0.3 to 0.8 ns.