Photochemical properties of porphyrin films covering curved surfaces of optical fibers

Surface organization and photochemistry of Langmuir–Blodgett (LB) monolayers of 10 mol-% 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (PFP) in an octadecylamine (ODA) matrix on flat quartz and tapered optical fiber surfaces are studied. Previous investigations of PFP films on flat surfaces had revealed that they exhibit a relatively long fluorescence lifetime (∼4 ns). In this Letter we show that the fluorescence lifetime of PFP films deposited on optical fiber-tapers with diameters between 10 and 20 μm is ten times shorter than that measured for the flat surface, being about 0.3 ns. Besides, films on tapered fibers are found to aggregate into domains with typical sizes smaller than those on flat surfaces.