Excitation-energy dependence of the radiative decay rate of s-triazine vapor: Participation of a higher singlet electronic state than S1 in the fluorescence emission

Emission spectra, quantum yields and decays of the fast emission component of s-triazine vapor following excitation into various vibronic levels in S₁ are reported. A monotonic increase of the radiative decay constant with increasing excitation energy suggests that a singlet electronic state higher than S₁ should participate in the fluorescence emission.