Concentration dependence of fluorescence

 

1. Re-absorption of emitted radiation

 

* Quantum yield decrease down to 0

* Emission maximum shifts to longer wavelength

 

2. Dimers

 

M + M --> M₂

 

* Absorption spectrum shifts to longer wavelength

* Fluorescence at optimum wavelength decreases

 

3. Excimere = excited dimers

 

M* + M --> dimer*

 

dimer --> M* + M

dimer* --> M + M

dimer* --> M + M + hn

 

Forming of excimers as a dynamic fluorescence quenching