where k1 is the rate constant of the formation of the encounter complex, k-1 is the rate constant for the dissociation of the encounter complex and k2 is the rate constant for the unimolecular reaction between A and B in complex to form products. If k2<<k-1 the reaction is under chemical control and the reaction of A and B is very slow compared to the separation from the solvent cage. If k2>>k-1 the reaction is diffusion controlled and the A-B reaction occurs much faster than the separation from the solvent cage in which case the rate constant can be called kdiff and calculated using the Stokes-Einstein-Smoluchiowski (SES) Equation, (2) where is the viscosity in Nsdm-2, T is temperature in K, and R is the gas constant 8.314 J/molK. ŋ The reaction between anthracene and CBr4 takes place only when exposed to light and is intrinsically fast. The CBr4 the fluorescence of the anthracene. Assuming a diffusion controlled “extinguishes” reaction and using the steady state Stern-Volmer relation where [Q] is the concentration of CBr4, is the slope of the Stern-Volmer plot, KSV is the Stern-Volmer constant (dm3mol-1), and is the ratio of the background intensity to the instrument response (3) . kq can be compared with kdiff. The Stern-Volmer plot should be linear following the assumption that there is quenching becomes more significant and no “static” quenching. However, at high concentrations static deviations from the linear nature of the S-V plot can be expected. The effects of static quenching can be calculated using (4) where is compared to that from Equation 3, [Q] is the concentration of CBr4, is calculated from the slope of the S-V plot, NA is and Y is defined by Avagadro’s number (5) where
where k1 is the rate constant of the formation of the encounter complex, k-1 is the rate constant for the dissociation of the encounter complex and k2 is the rate constant for the unimolecular reaction between A and B in complex to form products. If k2<<k-1 the reaction is under chemical control and the reaction of A and B is very slow compared to the separation from the solvent cage. If k2>>k-1 the reaction is diffusion controlled and the A-B reaction occurs much faster than the separation from the solvent cage in which case the rate constant can be called kdiff and calculated using the Stokes-Einstein-Smoluchiowski (SES) Equation, (2) where ŋ is the viscosity in Nsdm-2, T is temperature in K, and R is the gas constant 8.314 J/molK. The reaction between anthracene and CBr4 takes place only when exposed to light and is intrinsically fast. The CBr4 “extinguishes” the fluorescence of the anthracene. Assuming a diffusion controlled reaction and using the steady state Stern-Volmer relation where [Q] is the concentration of CBr4, is the slope of the Stern-Volmer plot, KSV is the Stern-Volmer constant (dm3mol-1), and is the ratio of the background intensity to the instrument response (3) . kq can be compared with kdiff. The Stern-Volmer plot should be linear following the assumption that there is no “static” quenching. However, at high concentrations static quenching becomes more significant and deviations from the linear nature of the S-V plot can be expected. The effects of static quenching can be calculated using (4) where is compared to that from Equation 3, [Q] is the concentration of CBr4, is calculated from the slope of the S-V plot, NA is Avagadro’s number and Y is defined by (5) where