The quenching mechanism of 9-cyanoanthracene (I) fluorescence by carbazole and its derivatives was studied. The results show that the quenching process can be in three different ways: exciplex formation, H-bonding formation in the excited state of I and general collision. All the above quenching effects chiefly come from charge transfer interation. In addition, the steric hindrance is also important for exciplex formation. The photophys. rate constants were obtained based on Ware kinetics scheme of exciplex formation and dissociation Both steadystate and transient fluorescence measurements were employed for the determination of the rate constants

Key words: CARBAZOLE, CYANO GROUP, SPATIAL STRUCTURE, ANTHRACENE P, CHARGE TRANSFER, FLUORESCENCE QUENCHER, INTERACTIONS, N-BENZYL GROUP, CYCLOBUTANE, QUENCHING