Broadband Multiphoton Upconversion Fluorescence of Novel Dendrimers by a Femtosecond Ti∶Sapphire Laser
QIAN Ying*, HU Kai-Ming, ZHOU Zhi-Qiang, Lü Chang-Gui, CUI Yi-Ping
2010, 31(11):
2268-2274.
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The multiphoton absorption and multi-photon-excited upconversion fluorescence of dendrimers, 1,2,4,5-tetra(4-N,N-diphenylaminostyryl)benzene(TPAB), 1,2,4,5-tetra[4-N,N-di(4-bromophenyl)aminostyryl]benzene(TPAB-Br) and 1,2,4,5-tetra{4-{N,N-bis{4-{4-[5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]styryl}phenyl}amino styryl}benzene(TPAB-OXA), were measured by a femtosecond Ti∶sapphire laser. The absorption, fluorescence emission and fluorescence lifetime of these octupolar chromophores were investigated. Pumped by a femtosecond laser at 1300 nm and 800 nm, strong upconversion fluorescence were observed. The maximum peaks of two-photon fluorescence in the solution of CH2Cl2 are at 569 nm for TPAB, at 535 nm for TPAB-Br and at 621 nm for TPAB-OXA, respectively. The three-photon excited fluorescence with the central wavelength at 566 nm for TPAB, at 534 nm for TPAB-Br and at 610 nm for TPAB-OXA in the solution of CH2Cl2 were observed. The two-photon absorption cross-section of chromophores obtained by nonlinear transmission method was 61.86×10-50 cm4\5s/photon for TPAB and 65.98×10-50 cm4\5s/photon for TPAB-OXA in the solution of THF. Large optical power limiting was demonstrated for the octupolar chromophores. Their three-photon absorption coefficients of 1300 nm in THF were 3.88×10-79, 7.76×10-79 and 27.17×10-79 cm6\5s2, respectively. The dendrimers displayed large multi-photon absorption and strong upconversion fluorescence properties.
