Fluorescence upconversion properties of a chiral polybinaphthyl induced by two-photon absorption

The fluorescence properties of a chiral polymer based on optically active polybinaphthyls were studied in tetrahydrofuran solution. One-photon excited fluorescence of the polymer was located in the range of similar to 596 nm and the corresponding lifetime was similar to 4.38 ns. From the excitation spectra and emission spectra excited at 800 nm, the upconversion fluorescence emission was observed. When excited by using 800 nm fs laser pulses with different input irradiances, the peak fluorescence intensity of the solution provides square dependence with the input irradiance power, giving an evidence for two-photon excited fluorescence. Furthermore, open aperture Z-scan measurements were performed at different irradiation intensities to confirm two-photon absorption property of the solution at 800 nm excitation. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012