Radiation propagation time broadening of the instrument response function in time-resolved fluorescence spectroscopy

It is shown that radiation propagation may affect time-resolved fluorescence measurements involving millimetre-sized systems and picosecond time scales. For this purpose, the effect of the excitation beam width on the instrument response function is studied. Experimental results for a scattering suspension of silica nanoparticles in a square 1 cm cell are analysed according to the developed model. The model accounts well for the observations, the retrieved parameters being in very good agreement with expectations.