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Samples of dipyrromethene-BF2 dye PM597 incorporated in copolymers of 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) with methyl methacrylate (MMA) and 2-hydroxyethylmethacrylate (HEMA), and in terpolymers of MMA, HEMA and TMSPMA are characterized. The absorption cross-section spectra, stimulated emission cross-section spectra, and the excited-state absorption cross-section at 527 nm are determined. The fluorescence quantum distributions and fluorescence lifetimes are measured. The photo-degradation is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted. PM597 solid state samples are compared with PM597 in liquid ethyl acetate solution. The fluorescence quantum yield of PM597 is higher in doped samples (around 70%) compared to PM597 in ethyl acetate (43%). The excited-state absorption cross-section was found to be negligibly small. The photo-stability is considerably larger in the polymeric samples compared to the liquid solutions. [ABSTRACT FROM AUTHOR]

The lasing properties of analogues of the commercial laser dye pyrromethene 567 (PM567) incorporated (dissolved or copolymerized) into polymeric matrices have been studied using both linear and cross-linked methyl methacrylate-based copolymers with different degrees of functionalization. All synthesized dyes have the chromophore core of PM567 but with an ω-acyloxypolymethylene chain at position 8. In general, the new materials exhibited laser emission with higher efficiencies and much higher photostabilities than those containing the commercial dye PM567 under the same experimental conditions. Lasing efficiencies of up to 40% were obtained under transversal pumping at 534 nm. The highest photostabilities, with the laser output remaining stable or dropping by less than 15% after 100 000 pump pulses at the same position of the sample, were reached in cross-linked materials with dyes covalently linked to the polymeric chains. When the polymeric samples were incorporated into a grazing-incidence grating oscillator, narrow-line-width operation with tuning ranges of up to 40 nm was obtained. These results show that efficient and photostable solid-state dye lasers competitive with their liquid counterparts can be developed by adequate chemical modifications in the dye molecules, as well as by the selection of appropriate polymeric formulations. [ABSTRACT FROM AUTHOR]

We report on the laser action of modified dipyrromethene.BF[sub 2] complexes both dissolved in poly(methyl methacrylate) and copolymerized with methyl methacrylate. All recently synthesized dyes have the chromophore core of laser dye pyrromethene 567, differing in the substituent in position 8. The new dyes showed important and most significant increases in both lasing efficiency and photostability. When the laser samples were pumped transversely at 534 nm, laser emission was obtained with efficiencies of over 30% in most cases, to be compared with a lasing efficiency of 12% exhibited by reference dye pyrromethene 567 under the same experimental conditions. Some of the materials exhibited highly photostable laser action, with no sign of degradation in the laser output after 60000 pump pulses at the same position of the sample at a repetition rate of 10 Hz, whereas the laser emission of reference dye pyrromethene 567 dropped to zero after less than 40000 pump pulses. [ABSTRACT FROM AUTHOR]

Abstract. Laser-induced opto-acoustic calorimetry has been used to examine the thermo-elastic properties of two polymer matrices doped with tinuvin-P and the radiation-less decay processes of rhodamine 6G (Rh6G) in them. The matrices assayed were methyl methacrylate (MMA) homopolymers P(MMA), and methyl methacrylate and 2-hydroxyethyl methacrylate (HEMA) copolymers P(MMA: HEMA). A slight difference in the thermo-elastic properties of the polymers, namely their adiabatic expansion coefficients, has been detected and found to correlate with the long-term stability of the laser material. This suggests a key role of the heat-dissipation processes in the photostability of these polymeric materials. On the other hand, the fluorescence quantum yield of Rh6G is shown to vary with the polymer-matrix composition in a way consistent with its lasing efficiency. The Rh6G absorption and fluorescence quantum yield also change dramatically upon increasing its concentration, which suggests the co-existence of different Rh6G forms with different photophysical properties. PACS: 81.70.C; 42.70.H [ABSTRACT FROM AUTHOR]

Abstract. The lasing properties of coumarin 503 (C503) dissolved in pure poly(methyl methacrylate) homopolymer and in copolymers of methyl methacrylate with 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and styrene have been investigated. The laser samples were transversely pumped at 337 nm with 1.2-mJ pulses from a nitrogen laser. The influence on the C503 laser performance of parameters such as dye concentration, viscoelasticity of the matrix, and degree of crosslinking of the polymeric chains were examined. Lasing efficiencies of up to 19% and lifetimes (defined as a 90% efficiency drop) of 2600 pulses at 2Hz repetition rate were demonstrated. Conditions that could result in an increase of dye photostability by the addition of 1,4-diazobicyclo[2.2.2]octane or cyclooctatetraene are discussed. [ABSTRACT FROM AUTHOR]

Abstract: We report the synthesis, photophysical properties and evaluation of laser dye of a new BODIPY dye with a 3-styryl substituent, PMS, and with the rest of the substituents as in the commercial dye PM567. PMS shows an emission band at 584nm in methanol, i.e. displaced ca. 50nm to longer wavelengths with regard to the green-emission band of PM567, as well as a high-fluorescence quantum yield (0.82) and also a high-molar absorption coefficient (105 M−1 cm−1) in the same solvent. The laser action of the new dye has been analyzed under transversal pumping at 532nm, 5.5mJpulse−1 and up to 10Hz repetition rate, in both liquid phase and incorporated into solid polymeric matrices of methyl methacrylate copolymerized with crosslinking or fluorinated monomers. Lasing emission at 602–610nm, with maximum efficiencies of 18%, were reached in these media. In solid-fluorinated matrices, good lasing photostabilities were established, with 30% of the initial laser output remaining after 100,000 pump pulses at 10Hz. [Copyright &y& Elsevier]

Abstract: Analogues of the dipyrromethene-BF2 dye PM567 modified at the 8-position by acetoxymethyl (P1Ac), s-acetoxypentyl (P5Ac), and p-acetoxymethylphenyl (PAr1Ac) groups are studied in ethyl acetate solution. PM567 modified at the 8-position by methacryloyloxymethyl (P1MA), s-methacryloyloxypentyl (P5MA), and p-methacryloyloxymethylphenyl (PAr1MA) groups have been copolymerized with methyl methacrylate (MMA), and these solid samples are also studied. The absorption cross-section and stimulated emission cross-section spectra are determined. The fluorescence quantum distributions and fluorescence lifetimes are measured. Saturable absorption measurements with picosecond laser excitation are carried out for excited-state absorption cross-section determination at the excitation wavelength. The photo-degradation of the dyes is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted. [Copyright &y& Elsevier]