Comparative analysis of conjugated alkynyl chromophore-triazacyclononane ligands for sensitized emission of europium and terbium

A series of europium and terbium complexes based on a functionalized triazacyclononane carboxylate or phosphinate macrocyclic ligand is described. The influence of the anionic group, that is, carboxylate, methylphosphinate, or phenylphosphinate, on the photophysical properties was studied and rationalized on the basis of DFT calculated structures. The nature, number, and position of electron-donating or electron-withdrawing aryl substituents were varied systematically within the same phenylethynyl scaffold in order to optimize the brightness of the corresponding europium complexes and investigate their two-photon absorption properties. Finally, the europium complexes were examined in cell-imaging applications, and selected terbium complexes were studied as potential oxygen sensors

Croissance assistée de nanostructures par absorption à 2 photons

International audienc

"Two-photon induced fabrication of gold microstructures in polystyrene sulfonate thuin filmd using a ruthenium (II) dye as photoinitiator"

International audienc

Two-photon induced fabrication of gold microstructures in polystyrene sulfonate thin films using a ruthenium(II) dye as photoinitiator.

International audienc

Two-photon fabrication of three-dimensional silver microstructures in microfluidic channels for volumetric surface-enhanced Raman scattering detection

International audienceWe report on the nonlinear photochemistry fabrication of three-dimensional silver (Ag) microstructures in microfluidic channels for volumetric surface-enhanced Raman scattering (3D SERS). The fabrication of high resolution 3D Ag microstructures is obtained by a two-photon induced reduction process of silver cations, which is restricted at the focal point of a Q-switched Nd:YAG microlaser (sub-nanosecond pulses at 1064 nm). Firstly, 3D Ag micro-pillars made on cover glass showed a 3D SERS detection limit of Oxazine 720 as low as 10−8 M. Secondly, we directly fabricated 3D microstructures within microfluidic channels, and demonstrated their 3D SERS capability. The micro-cube geometry gave a significantly larger 3D SERS signal than the micro-pillar geometry. This result demonstration is paving the way for further optimization routes by varying the geometry, the size, and the density of complex 3D structures which can be obtained by direct laser writing based on two-photon induced chemistry

Three-dimensional microfabrication by two-photon-initiated polymerization with a low-cost microlaser

International audienceFabrication of submicrometer structures by two-photon-initiated polymerization is performed with an inexpensive and low-power microlaser. This is made possible by the design of photoinitiators with strong two-photon absorption cross sections. We analyze the influence of both material properties and irradiation conditions on the two-photon polymerization rate and show that resins based on our highly sensitive two-photon photoinitiator can be solidified with microlaser excitation, whereas commercial UV photoresins require ultrashort and intense laser pulses

Design of Dipicolinic Acid Ligands for the Two-Photon Sensitized Luminescence of Europium Complexes with Optimized Cross-Sections

International audienceThe multistep synthesis of an extensive series of push−pull donor-π-conjugated dipicolinic acid ligands is described. The charge transfer character of the ligand can be tuned by changing the donor group (CH2R, OR, SR, or NR2) or the nature of the conjugated backbone (phenyl, phenylethynyl, naphtylethynyl, bis(phenylethynyl), or chalcone). The photophysical properties of related D3 symmetric europium complexes (absorption and luminescence) were measured. Experiments using two-photon sensitized luminescence of a EuIII complex reveal large two-photon absorption (TPA) cross-section values (775 GM at 740 nm) in dichloromethane. Furthermore, some structure−property relationships can be derived from this systematic study, allowing an optimization of TPA properties of lanthanide complexes

Quadratic phase modulation and diffraction-limited microfocusing generated by pairs of subwavelength dielectric scatterers

Diffractive approaches are needed when refractive microlenses reach their focusing limit at the micron-scale in visible light. Previously, we have reported on micron-sized optical lenses based on the diffraction of metallic nanowires. Here, we extend our study to lenses based on pairs of subwavelength dielectric scatterers. Using simulations by two-dimensional finite element method, we demonstrate that focusing holds for pair spacings as small as the wavelength-size. For pairs with distances between inner walls larger than about 1.2λ, the scattered waves generate a quadratic phase modulation on the total propagating field leading to a diffraction-limited focusing i.e. an effective optical lens effect with high numerical aperture. In addition, they have low sidelobe intensities, long depths of focus, and they have a low sensitivity with polarization. For pairs with inner wall distances smaller than about 1.2λ, the focusing phase modulation is accumulated during the propagation through the dielectric pair structure. In this work, we report only on the experimental demonstration for the case of larger wall separation to emphasize on the scattered wave effect on micro-focusing. A pair of parallel polymer lines (cylindrical lens), and a grid of polymer lines (square microlens array) with 2 μm-spacing were fabricated by two-photon induced polymerization. Their focal lengths are comparable to their separating distances, their spot-sizes are 0.37 μm and 0.28 μm at wavelength 530 nm, and their focusing efficiencies are 70% and 60%, respectively