Fig. 3.

(a) A framework for understanding the nature of fluorophore instabilities. (b) Kinetic regimes that lead to different behaviors of a fluorophore. TSQ: triplet state quencher; ROX and ROX’: reducing or oxidizing agents. t_exp: the exposure time for each frame of the measurement. Regime 1 occurs when

k_et[O₂] >> k^ts_isc+k_tsq[TSQ], k_rox[ROX],

and the fluorophore photobleaches quickly. Regime 2 occurs when

k_rox[ROX] >> k_et[O₂], k^ts_isc +k_tsq[TSQ];

k_rox’[ROX’] ≤ 1/ t_exp,

and the fluorophore blinks frequently. Regime 3 occurs when

k^ts_isc+ k_tsq[TSQ] >> k_et[O₂], k_rox[ROX];

or k_rox[ROX] >> k_et[O₂], k^ts_isc +k_tsq[TSQ];

k_rox’[ROX’] >> 1/ t_exp,

and the fluorophore lasts long and rarely blinks.