I have to explain in few lines the fluorescence photo physics behind the single molecule localisation microscopy (using STORM), I would like to know if my explanation is correct, thanks.

Question

In Single Molecule Localization Microscopy (STORM), achieving super-resolution relies in part on selectively switching fluorophores between ON and OFF states. This process leverages the photophysical properties of fluorophores.

By manipulating the energetic states of fluorophores, particularly utilizing the radical anion state's long-lived nature, a controlled subset of fluorophores can be directed into a non-emitting state. Adjusting thiol and oxygen concentrations, along with light irradiance, allows for the creation of a state where only a sparse subset of fluorophores is in the emitting ON state.

Simplifying the model, ground and excited singlet states are grouped into the ON state, while the triplet state and radical anion states constitute the OFF state. A continuous-time Markov chain model helps understand transitions between states. Laser irradiance influences transition rates, and UV light enhances the return rate to the ON state.

STORM utilizes photoswitching, controlling the transition between ON and OFF states with light. Laser adjustments balance the relative number of molecules in each state, facilitating the isolation and localization of single molecules. In contrast, PALM employs photoactivation, activating fluorophores with low-irradiance UV light for visible spectrum fluorescence and subsequent localization. The efficiency of these processes is governed by the interplay of activation and deactivation rates.