Reversible fluorescence quenching: Generalized Stern–Volmer equations on the basis of self-consistent quenching constant relations

• Published in: The Journal of chemical physics 2000-04, Vol.112 (16), p.7152-7157
• Main Author: Naumann, Wolfgang
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.481325

For irreversible fluorescence quenching in solution, it is shown that the kinetic prediction of the Smoluchowski approach, which is exact under target model conditions, can also be alternatively formulated in terms of well-defined non-Markovian rate equations. For the well-known superposition approximation, it is demonstrated that the definition of an approximate quenching constant by a self-consistent relation can also be formally transferred to the reversible quenching processes if only the low-density limits of the net forward rate kernels in the generalized rate equations are known. Fluorescence quenching by reversible excimer formation and by reversible excitation transfer meet this requirement due to the recent findings of several authors. It is demonstrated that the proposed quenching constant approximation procedure leads to nonlinear plots with positive curvature which correct the zeroth-order linear plots in the higher quencher concentration region. The influence of the yield-reducing back reaction effect is discussed.