Predictions of Two Photon Absorption Profiles Using Time-Dependent Density Functional Theory Combined with SOS and CEO Formalisms

Two-photon absorption (2PA) and subsequent processes may be localized in space with a tightly focused laser beam. This property is used in a wide range of applications, including three dimensional data storage. We report theoretical studies of 5 conjugated chromophores experimentally shown to have large 2PA cross-sections. We use the Time Dependent Density Functional Theory (TD-DFT) to describe the electronic structure. The third order coupled electronic oscillator formalism is applied to calculate frequency-dependent second order hyperpolarizability. Alternatively, the sum over states formalism using state-to-state transition dipoles provided by the a posteriori Tamm-Dancoff approximation is employed. It provides new venues for qualitative interpretation and rational design of 2PA chromophores. © 2009 Springer Berlin Heidelberg

Mechanistic Aspects of Maleimide-Donor Photocopolymerizations

The relative rates in the alternating copolymerization of a difunctional maleimide and conventional alkenyl ether have been investigated and compared to the exomethylenic aryl(alkyl)dioxolane, 4-methylene-2-phenyl-1,3-dioxolane, using real-time infrared (RTIR) spectroscopy. The mechanistic differences in propagation between the two donors have been examined and evaluated by laser flash photolysis. It is shown that structural modifications which increase the electron density in the vinylic C=C bond produce higher rates of copolymerization. Copolymerization studies indicate that the relative extent of ring opening decreases with increasing temperature

Ultrafast spectroscopy, superluminescence and theoretical modeling of a two-photon absorbing fluorene derivative

A comprehensive study of photophysical and photochemical properties of an unsymmetrical fluorene derivative is presented, including linear absorption, fluorescence excitation anisotropy, photochemical stability, steady-state fluorescence, and fluorescence lifetimes in organic solvents of different polarities. Nonlinear optical properties were investigated using Z-scan measurements of degenerate two-photon absorption and femtosecond pump-probe spectroscopy. The strongly fluorescent compound exhibited good photostability, positioning it for use in a number of applications. A dramatic increase in fluorescence intensity along with spectral narrowing was observed under femtosecond pumping, demonstrating amplified spontaneous emission. An extensive set of experimental data is rationalized based on essential state models

Photostability enhancement of an azobenzene photonic polymer

International audienceWe have found that the presence of a methacrylate group on an azobenzene electro-optic chromophore can provide an enhancement in photostability of up to one or two orders of magnitude. Systematic studies involving the change in chromophore structure and atmospheric environmentindicate that the photostabilization is due to antioxidant action by the unsaturated functional grou

Observation of tunable two-photon induced excited-state and three-photon absorption phenomena by structure in oligomerfluorene derivatives

10.1007/s00339-011-6538-2Applied Physics A: Materials Science and Processing1054891-895APAM