Femtosecond fluorescence dynamics imaging using a fluorescence up-conversion microscope.

Femtosecond fluorescence dynamics imaging microscopy was performed. Femtosecond fluorescence dynamics images were constructed based on the "mean" fluorescence decay or rise time constants that were evaluated by the time-resolved intensity sampling using a fluorescence up-conversion microscope. This dynamics imaging microscopy was carried out for the organic microcrystals alpha-perylene and tetracene-doped anthracene microcrystal, and ultrafast dynamics in the organic microcrystals were clearly imaged in the two-dimensional manner. For the alpha-perylene microcrystal, the obtained dynamics images showed that the crystal edges exhibited relatively shorter free exciton and the Y-state lifetimes compared to the crystal center, reflecting the higher concentration of defects. For the tetracene-doped anthracene microcrystal, the image was constructed based on the time constant of excitation energy transfer from anthracene to tetracene. By experiments changing the doping ratio of tetracene in anthracene, it was concluded that the inhomogeneity observed in the dynamics image arises from the difference in the local concentration of tetracene in the mixed crystal.