Synthesis and nonlinear optical properties of a new two-photon photopolymerization initiator EPVPVC

A new two-photon free-radical photopolymerization initiator 9-ethyl-3-{2-[4-(2-pyrid-4-yl)-vinylphenyl]-vinyl}-carbazole (abbrev. EPVPVC) has been synthesized and structurally characterized by H-1 NMR spectra, C-13 NMR spectra and elemental analyses. Linear absorption, one-photon induced fluorescence. one-photon fluorescence lifetime, one-photon fluorescence quantum yield and two-photon induced fluorescence were experimentally studied. The calculated two-photon absorption cross-section is as high as 56.6 x 10(-50) cm(4).s.photon(-1). When pumped with 780 nm laser irradiation, EPVPVC exhibits strong two-photon induced fluorescence of 536 nm. A microstructure using EPVPVC as initiator has been fabricated under irradiation of 200 fs, 76 MHz Ti: sapphire femtosecond laser at 780 nm. The possible mechanism of photopolymerization was discussed based on quantum chemistry calculations.