Fig. 2: LIGHTNING data collection on RSFP solutions.

a Four illuminations involving lights at λ₁ = 488 and λ₂ = 405 nm at respective intensities I₁ and I₂ (I₁, I₂ in Ein m⁻² s⁻¹; Iα: I₁ = 0.1, IIα: I₁ = 0.1 and I₂ = 0.1, Iβ: I₁ = 50, IIβ: I₁ = 50 and I₂ = 20) yield four fluorescence evolutions I_F (markers; each scaled by the difference between the maximal and minimal values) at λ₃ = 525 nm. Whereas Iα, IIα, and Iβ provide a single characteristic time after monoexponential fitting (lines), up to two characteristic times can be retrieved in IIβ depending on the frequency and time window of fluorescence acquisition; b Inverse of the characteristic time obtained for a series of illuminations I (disks) (II (circles), resp.) versus light intensity I₁ (I₂, resp. at I₁ = 0.2 Ein m⁻² s⁻¹). The vertical dotted line separates the low-intensity regime for which the rate-limiting step is photochemical from the high-intensity regime for which the rate-limiting step is thermal. 1 (grey markers and blue lines) and 2 (black markers and red lines) are representatives of slow and fast photoswitching RSFPs respectively.