DOI: 10.1007/s00340-006-2439-z Appl. Phys. B 86, 537–545 (2007) Lasers and Optics Applied Physics B t. susdorf 1 d. del agua 1, ∗ a. tyagi 1 a. penzkofer 1, ✉ o. garc´ ıa 2 r. sastre 2 a. costela 3 i. garc´ ıa-moreno 3 Photophysical characterization of pyrromethene 597 laser dye in silicon-containing organic matrices 1 Institut II – Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany 2 Instituto de Ciencia y Tecnolog´ ıa de Pol´ ımeros, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain 3 Instituto de Qu´ ımica F´ ısica “Rocasolano”, CSIC, Serrano 119, 28006 Madrid, Spain Received: 30 June 2006 Published online: 9 September 2006 • © Springer-Verlag 2006 ABSTRACT Samples of dipyrromethene-BF 2 dye PM597 in- corporated in copolymers of 3-(trimethoxysilyl)propyl meth- acrylate (TMSPMA) with methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA), and in terpolymers of MMA, HEMA and TMSPMA are characterized. The absorption cross-section spectra, stimulated emission cross-section spec- tra, 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 sam- ples (around 70%) compared to PM597 in ethyl acetate (43%). The excited-state absorption cross-section was found to be neg- ligibly small. The photo-stability is considerably larger in the polymeric samples compared to the liquid solutions. PACS 42.55.-f; 78.45.+h; 78.55.-m; 78.40.Me 1 Introduction The development of tunable solid-state organic dye lasers is a subject of considerable interest and research activ- ity [1]. Compared to conventional liquid dye lasers they have the advantage of being free of solvent handling, having a small size, and being easy to operate. For high-performance solid- state dye lasers highly photo-stable dyes with low quantum yield of triplet formation and low triplet absorption cross- section in the lasing wavelength region are required. The dipyrromethene dyes are well established laser dyes with low triplet absorption losses in the laser emission re- gion [2]. They find application in solid-state dye lasers be- cause of their high laser efficiency and high photo-stabili- ty [1, 3, 4]. The dye pyrromethene 567 (PM567) has been applied in solid-state lasers [5–11]. It is tunable over a wave- length range from 545 nm to 585 nm [8]. At the 8-position ✉ Fax: +49-941-9432754, E-mail: alfons.penzkofer@physik.uni-regensburg.de ∗ On leave from Instituto de Ciencia y Tecnolog´ ıa de Pol´ ımeros, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain modified dyes of PM567 were synthesized, doped into poly- mer matrices and covalently bound to polymers in order to im- prove their laser performance and photo-stability [4, 10–15]. The dye pyrromethethene 597 (PM597, full name: 1,3,5, 7,8-pentamethyl-2,6-di-t-butylpyrromethene-difluoroborate complex) was used as gain medium in various solid-state lasers with high performance data [8, 16–24]. Laser wave- length tuning was achieved over a range from 572 nm to 612 nm in the solid state lasers [8]. Amplified spontaneous emission and phase-conjugated backward stimulated emis- sion was achieved on PM597 in PMMA [25]. The laser performance degradation with the number of shots of PM597 solid-state dye lasers was studied in [19, 20, 22]. The photo- physical properties of PM597 in organic solvents was studied in detail in [26]. The photo-degradation of PM597 in acetoni- trile and n-hexane was analyzed in [27]. In this paper some photo-physical characterization (ab- sorption and emission spectra, fluorescence quantum yields and lifetimes, excited-state absorption, and photo-degrada- tion) of the dye PM597 in silicon-containing organic matri- ces [22] is carried out. These matrices are (i) copolymers of methyl methacrylate (MMA) with 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) called COP(MMA-TMSPMA), (ii) sol–gel hydrolysis condensed copolymers of MMA with TMSPMA called COPH(MMA-TMSPMA), (iii) copolymers of 2-hydroxyethyl methacrylate (HEMA) and TMSPMA called COP(HEMA-TMSPMA), and (iv) terpolymers of MMA, HEMA and TMSPMA called TERP(MMA-HEMA- TMSPMA). The behaviour of PM597 in these polymer matri- ces is compared with the behaviour of PM597 in the solvent ethyl acetate. The structural formulae of PM597, MMA, HEMA, and TMSPMA are shown in Fig. 1. 2 Experimental The dipyrromethene-BF 2 dye PM597 used in the dye doped polymer preparation was purchased from Exci- ton, and used as received. For spectroscopy studies on PM597 in ethyl acetate, PM597 was bought from Radiant Dyes. The other used chemicals, MMA, HEMA, TMSPMA, and 2, 2 ′ -azobis(isobutyronitrile) (AIBN) were purchased from Aldrich. MMA, HEMA, and TMSPMA were vacuum dis- tilled. AIBN was re-crystallized in ethanol before use. This is