Pressure effect on the kinetic of fluorescence photobleaching

We investigate by fluorescence microscopy the bulk fluorescence photobleaching of coumarin 1 and fluorescein in different solvents as a function of pressure up to 3.5 kbar. We show that for coumarin 1, the decrease in the fluorescence intensity is well described by a single exponential function whose characteristic time decreases with pressure following a power law with exponent close to -0.29. Fluorescein photobleaching follows a double exponential function, the shorter time of which seems to follow a similar behavior as a function of pressure.