SELF-QUENCHING OF AZULENE FLUORESCENCE IN CYCLOHEXANE

The self-quenching of azulene fluorescence in cyclohexane was studied by steady-state and time resolved fluorescence measurements. The quenc hing proceeds by a short-range exchange type non-radiative energy tran sfer from S-2 to S-1 owing to a substantial overlap between the S-2--> S-0 fluorescence and the S-0-->S-1 absorption spectra of azulene. At r oom temperature the quenching occurs on the encounter of an excited az ulene molecule with a ground state molecule with a diffusion-controlle d rate constant, k(0) = 1.4 X 10(10) M(-1) s(-1).