<Dd> (S 1) = (S 1) 0 e − Γ t (\ displaystyle \ left (S_ (1) \ right) = \ left (S_ (1) \ right) _ (0) e ^ (- \ Gamma t)) </Dd> <P> where (S 1) (\ displaystyle \ left (S_ (1) \ right)) is the concentration of excited state molecules at time t (\ displaystyle t), (S 1) 0 (\ displaystyle \ left (S_ (1) \ right) _ (0)) is the initial concentration and Γ (\ displaystyle \ Gamma) is the decay rate or the inverse of the fluorescence lifetime . This is an instance of exponential decay . Various radiative and non-radiative processes can de-populate the excited state . In such case the total decay rate is the sum over all rates: </P> <Dl> <Dd> Γ t o t = Γ r a d + Γ n r a d (\ displaystyle \ Gamma _ (tot) = \ Gamma _ (rad) + \ Gamma _ (nrad)) </Dd> </Dl> <Dd> Γ t o t = Γ r a d + Γ n r a d (\ displaystyle \ Gamma _ (tot) = \ Gamma _ (rad) + \ Gamma _ (nrad)) </Dd>

Explain one activity which reveals dispersion of light