Stern-Volmer relationship

The decay of the excited state S is through a number of processes shown in Eqn (1.32) with a combined first-order rate constant 

When a quencher Q (B in (1.32)) is added there is an additional path for deactivation 

It is easy to see that if Tq and t are the excited state lifetimes in the absence and in the presence of quencher, respectively, then 

This is the Stern-Volmer relationship with = k /k(j, and is an important basis for determining quenching rate constants after pulsed excitation. The quantum yield of (pro-duct)o can be measured without (0q) and with (0) quencher under continuous excitation (0 = moles of product/einsteins of light absorbed by system). Assuming that a steady state concentration of S exists in both cases. 

This represents a competitive, non-kinetic, method for determining relative rate constants for the photochemical system. The value of may be obtained after one direct determination of has been made. For an extensive compilation of quenching rate constants for excited states of metal complexes see Ref. 358. 

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Analysis of this scteme ows that for steady-state excitation, the Stern-Volmer relationship (62) and quantum yield ratio of excimer to monomer fluorescence (63) are obtained. 

The change in radical lifetimes on Vycor glass which had been degassed at various temperatures was determined by the effect of O2 upon the CgHg formation by means of the Stern-Volmer relationship ... 

Another mathematical model based on the relative contributions of static and dynamic quenching mechanisms in heterogeneous systems was derived by Carraway etal [8]. The light intensity in their model is described by a series of Stern-Volmer relationships... 

In this formulation, the lifetime of the excited singlet state in the absence of Q is denoted x, while that in the presence of Q is indicated as r. Often, r° is used to represent the lifetime of an excited state in the absence of quencher and x to represent the lifetime of an excited state in the presence of quencher. In that case, the Stern-Volmer relationship becomes... 

Reactions of this type can be studied by measuring the quantum yield of monomer fluorescence as a function of concentration. A simple kinetic analysis shows that the reaction scheme indicated above leads to the so-called Stern-Volmer relationship... 

Quantification of the Quenching Process The Stern-Volmer Relationship... 

Experimental data on diffusion constants are usually derived from some variation of the quenching of luminescence in a polymer by a mobile quencher or mobile chromophore or both. In the static measurement, the intensity of luminescence is measured as a function of quencher concentration and expressed in the form of a Stern-Volmer relationship... 

With continuous illumination, a steady-state analysis leads to the celebrated Stern-Volmer relationship ° ... 

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