Internal conversion and intersystem crossing in fluoropyridine vapors

► Fluorescence, excitation and sensitized phosphorescence excitation spectra of three fluoropyridine vapors were measured. ► The S1 → T1 intersystem crossing yields were determined by a sensitized phosphorescence method. ► Main nonradiative process is shown to be the S1 → S0 internal conversion. ► The internal conversion rates increase with increasing excitation energy. ► The increase of the intersystem crossing rates with increasing excitation energy is not significant.