Confocal fluorescence lifetime imaging microscopy method is used to obtain individual fluorescence intensity and
lifetime values of aromatic Perylene dye molecules encapsulated into PMMA based nanofibers. Fluorescence spectrum
of aromatic hydrocarbon dye molecules, like perylene, depends on the concentration of dye molecules and these dye
molecules display an excimeric emission band besides monomeric emission bands. Due to the dimension of a nanofiber
is comparable to the monomer emission wavelength, the presence of nanofibers does not become effective on the decay
rates of a single perylene molecule and its lifetime remains unchanged. When the concentration of perylene increases,
molecular motion of the perylene molecule is restricted within nanofibers so that excimer emission arises from the
partially overlapped conformation. As compared to free excimer emission of perylene, time-resolved experiments show
that the fluorescence lifetime of excimer emission of perylene, which is encapsulated into NFs, gets shortened
dramatically. Such a decrease in the lifetime is measured to be almost 50 percent, which indicates that the excimer
emission of perylene molecules is more sensitive to change in the surrounding environment due to its longer wavelength.
Fluorescence lifetime measurements are typically used to confirm the presence of excimers and to construct an excimer
formation map of these dye molecules.
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