Quenching effects upon the life-time of protonated 2-naphthamide S1 in aqueous solution

Abstract

Fluorescence life-time measurements are reported for the first excited singlet of the protonated 2-naphthamide species in acid solutions in the presence of chloride, perchlorate, and sulphamate ions. Except possibly with the sulphamate anion, the quenching effect of the hydrogen ion is much greater than that of the anions in this particular case. The life-time of [graphic omitted] in the absence of quencher is 29 ns and the quenching constant for H⁺, 3 × 10⁷ l. mol^–1 s^–1 at 25°C.