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Laser Dyes (laser + dye)
Selected AbstractsIntramolecular Charge Transfer in Pyrromethene Laser Dyes: Photophysical Behaviour of PM650CHEMPHYSCHEM, Issue 11 2004F. López Arbeloa Prof. Dr. Abstract Absorption and fluorescence (steady-state and time-correlated) techniques are used to study the photophysical characteristics of the pyrromethene 650 (PM650) dye. The presence of the cyano group at the 8 position considerably shifts the absorption and fluorescence bands to lower energies with respect to other related pyrromethene dyes; this is attributed to the strong electron-acceptor character of the cyano group, as is theoretically confirmed by quantum mechanical methods. The fluorescence properties of PM650 are intensively solvent-dependent. The fluorescence band is shifted to lower energies in polar/protic solutions, and the evolution of the corresponding wavelength with the solvent is analysed by a multicomponent linear regression. The fluorescence quantum yield and the lifetime strongly decrease in polar/protic solvents, which can be ascribed to an extra nonradiative deactivation, via an intramolecular charge-transfer state (ICT state), favoured in polar media. [source] Colloidal-Crystal Laser Using Monodispersed Mesoporous Silica SpheresADVANCED MATERIALS, Issue 41 2009Hisashi Yamada Monodispersed mesoporous silica spheres (MMSSs) are silica colloid particles with uniform mesopores and particle diameters. MMSS ionic colloidal crystals can be fabricated by self-organization and immobilization using a hydrogel. From measurements of the emission light of the gel-immobilized MMSSs where a laser dye was incorporated, laser emission occurred through the excitation by a YAG laser. [source] Structural Changes in the BODIPY Dye PM567 Enhancing the Laser Action in Liquid and Solid Media,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2007I. García-Moreno Abstract In the search for more efficient and photostable solid-state dye lasers, newly synthesized analogs of the borondipyrromethene (BODIPY) dye PM567, bearing the polymerizable methacryloyloxypropyl group at position 2 (PMoMA) or at positions 2 and 6 (PDiMA), have been studied in the form of solid copolymers with methyl methacrylate (MMA). The parent dye PM567, as well as the model analogs bearing the acetoxypropyl group in the same positions, PMoAc and PDiAc, respectively, have been also studied both in liquid solvents and in solid poly(MMA) (PMMA) solution. Although in liquid solution PMoAc and PDiAc have the same photophysical properties as PM567, PDiAc exhibited a photostability up to 10 times higher than that of PM567 in ethanol under 310,nm-irradiation. The possible stabilization factors of PDiAc have been analyzed and discussed on the basis of the redox potentials, the ability for singlet molecular oxygen [O2(1,g)] generation, the reactivity with O2(1,g), and quantum mechanical calculations. Both PMoAc and PDiAc, pumped transversally at 532,nm, lased in liquid solution with a high (up to 58,%), near solvent-independent efficiency. This enhanced photostabilization has been also observed in solid polymeric and copolymeric media. While the solid solution of the model dye PDiAc in PMMA showed a lasing efficiency of 33,%, with a decrease in the laser output of ca.,50,% after 60,000 pump pulses (10,Hz repetition rate) in the same position of the sample, the solid copolymer with the double bonded chromophore, COP(PDiMA-MMA), showed lasing efficiencies of up to 37,%, and no sign of degradation in the laser output after 100,000 similar pump pulses. Even under the more demanding repetition rate of 30,Hz, the laser emission from this material remained at 67,% of its initial laser output after 400,000 pump pulses, which is the highest laser photostability achieved to date for solid-state lasers based on organic polymeric materials doped with laser dyes. This result indicates that the double covalent linkage of the BODIPY chromophore to a PMMA polymeric matrix is even more efficient than the simple linkage, for its photostabilization under laser operation. [source] Syntheses and photophysical properties of some 4-arylpyridinium saltsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2001Charles J. Kelley A number of 4-arylpyridines, many methoxy substituted, were prepared by an efficient two-step method involving aryl Grignard addition to 1-methyl-4-piperidone and direct aromatization of the resulting 4-aryl-4-piperidinols. The pyridines were N -alkylated to give sulfonate salts desired for their fluorescent properties. Study of selected compounds as laser dyes revealed several structures to be efficient dyes lasing in the 530-550 nm range. Two new diazaquaterphenyls were prepared and were quaternized. These salts exhibited intense fluorescence in the 420-450 nm range, but would not lase. A phenolic azaterphenyl suitably substituted for excited state intramolecular proton transfer (ESIPT) did not fluoresce at all. [source] | |||||||||||||