1,720,987 research outputs found
Two-photon Absorption Spectrum In Diazoaromatic Compounds
No full textThis Letter studies the degenerate two-photon absorption (2PA) spectra of three diazoaromatic compounds using Z-scan with fs-pulses. The 2PA spectra exhibit resonant enhancement of the nonlinearity as the excitation approaches the linear absorption. The absence of 2PA to the ππ* band is related to the weaker donor/acceptor groups, and lower symmetry of diazoaromatic compounds, in agreement with our semi-empirical calculations. The higher magnitude of the 2PA cross-section, in comparison with single azoaromatics, demonstrates the positive effect of increasing conjugation. The decrease of 2PA cross-section with temperature is attributed to thermally induced torsions, which decreases the effective conjugation of diazoaromatic molecules. © 2008 Elsevier B.V. All rights reserved.4634-6360363Prasad, P.N., Willians, D.J., (1991) Introduction to Nonlinear Optical Effects in Molecules and Polymers, , Wiley Interscience, New YorkKawata, S., Sun, H.B., Tanaka, T., Takada, K., (2001) Nature, 412, p. 697Sun, H.B., Kawata, S., (2004) Advances in Polymer Science: NMR - 3D Analysis - Photopolymerization, , Springer-Verlag, Berlin p. 169Kawata, S., Kawata, Y., (2000) Chem. Rev., 100, p. 1777Mendonca, C.R., (2007) Opt. Commun., 273, p. 435Belfield, K.D., Ren, X., Van Stryland, E.W., Hagan, D.J., Dubikovski, V., Meisak, E.J., (2000) J. Am. Chem. Soc., 122, p. 1217Denk, W., Strickler, J.H., Webb, W.W., (1990) Science, 248, p. 73Kohler, R.H., Cao, J., Zipfel, W.R., Webb, W.W., Hansen, M.R., (1997) Science, 276, p. 2039Bhawalkar, J.D., He, G.S., Prasad, P.N., (1996) Rep. Prog. Phys., 59, p. 1041Herman, B., Wang, X.F., Wodnicki, P., Perisamy, A., Mahajan, N., Berry, G., Gordon, G., (1999) Applied Fluorescence in Chemistry Biology and Medicine, p. 496. , Retting B.S.W., Schrader S., and Seifert H. (Eds), Springer, New YorkZhou, G.Y., Wang, C., Lei, H., Wang, D., Shao, Z.S., Jiang, M.H., (2001) Chin. Phys. Lett., 18, p. 1120Oliveira, S.L., Correa, D.S., Misoguti, L., Constantino, C.J.L., Aroca, R.F., Zilio, S.C., Mendonca, C.R., (2005) Adv. Mater., 17, p. 1890Albota, M., (1998) Science, 281, p. 1653Belfield, K.D., Hagan, D.J., Van Stryland, E.W., Schafer, K.J., Negres, R.A., (1999) Org. Lett., 1, p. 1575Morel, Y., Stephan, O., Andraud, C., Baldeck, P.L., (2001) Synth. Met., 124, p. 237Wang, X.M., Wang, D., Zhou, G.Y., Yu, W.T., Zhou, Y.F., Fang, Q., Jiang, M.H., (2001) J. Mater. Chem., 11, p. 1600Reinhardt, B.A., (1998) Chem. Mater., 10, p. 1863Rochon, P., Gosselin, J., Natansohn, A., Xie, S., (1992) Appl. Phys. Lett., 60, p. 4Jiang, X.L., Li, L., Kumar, J., Kim, D.Y., Shivshankar, V., Tripathy, S.K., (1996) Appl. Phys. Lett., 68, p. 2619Jager, M., (1998) J. Opt. Soc. Am. B-Opt. Phys., 15, p. 781Cherioux, F., Audebert, P., Maillotte, H., Grossard, L., Hernandez, F.E., Lacourt, A., (1997) Chem. Mater., 9, p. 2921De Boni, L., (2002) Chem. Phys. Lett., 361, p. 209Antonov, L., Kamada, K., Ohta, K., Kamounah, F.S., (2003) Phys. Chem. Chem. Phys., 5, p. 1193De Boni, L., Misoguti, L., Zilio, S.C., Mendonca, C.R., (2005) ChemPhysChem, 6, p. 1121Neves, U.M., De Boni, L., Ye, Z.H., Bu, X.R., Mendonca, C.R., (2007) Chem. Phys. Lett., 441, p. 221De Boni, L., Piovesan, E., Misoguti, L., Zilio, S.C., Mendonca, C.R., (2007) J. Phys. Chem. A, 111, p. 6222Sheik-Bahae, M., Said, A.A., Wei, T.H., Hagan, D.J., Van Stryland, E.W., (1990) IEEE J. Quant. Electron., 26, p. 760Correa, D.S., De Boni, L., Misoguti, L., Cohanoschi, I., Hernandez, F.E., Mendonca, C.R., (2007) Opt. Commun., 277, p. 440Franken, P.A., Ward, J.F., (1963) Rev. Mod. Phys., 35, p. 23Orr, B.J., Ward, J.F., (1971) Mol. Phys., 20, p. 513Kamada, K., Ohta, K., Yoichiro, I., Kondo, K., (2003) Chem. Phys. Lett., 372, p. 386Mazumdar, S., Guo, D.D., Dixit, S.N., (1993) Synth. Met., 57, p. 3881Dirk, C.W., Cheng, L.T., Kuzyk, M.G., (1992) Int. J. Quant. Chem., 43, p. 27Birge, R.R., Pierce, B.M., (1979) J. Chem. Phys., 70, p. 165Rumi, M., (2000) J. Am. Chem. Soc., 122, p. 9500Zojer, E., Beljonne, D., Kogej, T., Vogel, H., Marder, S.R., Perry, J.W., Bredas, J.L., (2002) J. Chem. Phys., 116, p. 3646Kogej, T., Beljonne, D., Meyers, F., Perry, J.W., Marder, S.R., Bredas, J.L., (1998) Chem. Phys. Lett., 298, p. 1Andrade, A.A., Yamaki, S.B., Misoguti, L., Zilio, S.C., Atvars, T.D.Z., Oliveira, O.N., Mendonca, C.R., (2004) Opt. Mater., 27, p. 441Day, P.N., Nguyen, K.A., Pachter, R., (2005) J. Phys. Chem. B, 109, p. 1803Bicknell, R.T.M., Davies, D.B., Lawrence, K.G., (1982) J. Chem. Soc.-Faraday Trans. I, 78, p. 159
Photoinduced Birefringence In Di-azo Compounds In Polystyrene And Poly(methyl Methacrylate) Guest-host Systems
No full textAn investigation is presented of the optical storage capability, via photoinduced birefringence, for three di-azo compounds (Sudan dyes) incorporated into two polymer matrices, namely poly(methyl methacrylate) (PMMA) and polystyrene (PS). The optical birefringence was induced in the samples by using a diode-pumped frequency doubled Nd:YAG at 532 nm, while a He-Ne laser light at 632.8 nm was used to measure the induced birefringence in the sample. The results show lower dye mobility in PS than in PMMA matrices owing to the lower free volume that interferes with the efficiency of the birefringence photoinduced process. Some of the reasons for the lower efficiency of the induced birefringence of di-azo compounds compared to the mono-azo dyes are also discussed. © 2006 Elsevier B.V. All rights reserved.302216221Sekkat, Z., Dumont, M., (1991) Appl. Phys. B-Photophys. Laser Chem., 53, p. 121Natansohn, A., Rochon, P., Gosselin, J., Xie, S., (1992) Macromolecules, 25, p. 2268Xie, S., Natansohn, A.., Rochon, P., (1993) Chem. Mater., 5, p. 403Meng, X., Natansohn, A., Rochon, P., (1996) J. Polym. Sci. Part B-Polym. Phys., 34, p. 1461Meng, X., Natansohn, A., Barrett, C., Rochon, P., (1996) Macromolecules, 29, p. 946Mendonça, C.R., dos Santos Jr., D.S., Balogh, D.T., Dhanabalan, A., Giacometti, J.A., Zilio, S.C., Oliveira Jr., O.N., (2001) Polymer, 42, p. 6539Meng, X., Natansohn, A., Rochon, P., (1997) Polymer, 38, p. 2677Yesodha, S.K., Pillai, C.K.S., Tsutsumi, N., (2004) Progr. Polym. Sci, 29, p. 45dos Santos Jr., D.S., Bassi, A., Rodrigues, J.J., Misoguti, L., Oliveira Jr., O.N., Mendonça, C.R., (2003) Biomacromolecules, 4, p. 1502Ahlheim, M., Lehr, F., (1995) Macromol. Chem. Phys., 196, p. 243Andrade, A.A., Yamaki, S.B., Misoguti, L., Zilio, S.C., Atvars, T.D.Z., Oliveira Jr., O.N., Mendonça, C.R., (2004) Opt. Mater., 27, p. 441de Oliveira, M.G., Yamaki, S.B., Atvars, T.D.Z., (2004) J. Brazil Chem. Soc., 15, p. 253Christoff, M., Yamaki, S.B., de Oliveira, M.G., Atvars, T.D.Z., (2004) J. Appl. Polym. Sci., 92, p. 830Suzuki, H., (1967) An Application of Molecular Orbital Theory, , Academic Press, New YorkHooker, J.C., Burghardt, W.R., Torkelson, J.M., (1999) J. Chem. Phys., 111, p. 2779Dhanabalan, A., Mendonça, C.R., Balogh, D.T., Misoguti, L., Constantino, C.J.L., Giacometti, J.A., Zilio, S.C., Oliveira Jr., O.N., (1999) Macromolecules, 32, p. 5277dos Santos Jr., D.S., Mendonça, C.R., Balogh, D.T., Dhanabalan, A., Giacometti, J.A., Zilio, S.C., Oliveira Jr., O.N., (2001) Synthetic Met., 121, p. 1479Natansohn, A., Rochon, P., (2002) Chem. Rev., 102, p. 4139Zucolotto, V., Mendonça, C.R., dos Santos Jr., D.S., Balogh, D.T., Zilio, S.C., Oliveira Jr., O.N., Constantino, C.J.L., Aroca, R.F., (2002) Polymer, 43, p. 4645Zucolotto, V., Neto, N.M.B., Rodrigues, J.J., Constantino, C.J.L., Zilio, S.C., Mendonça, C.R., Aroca, R.F., Oliveira Jr., O.N., (2004) J. Nanosci. Nanotechnol., 4, p. 855Zucolotto, V., Strack, P.J., Santos, F.R., Balogh, D.T., Constantino, C.J.L., Mendonça, C.R., Oliveira Jr., O.N., (2004) Thin Solid Films, 453-54, p. 110Camilo, C.S., dos Santos Jr., D.S., Rodrigues, J.J., Vega, M.L., Campana, S.P., Oliveira Jr., O.N., Mendonça, C.R., (2003) Biomacromolecules, 4, p. 1583Christoff, M., Atvars, T.D.Z., (1999) Macromolecules, 32, p. 6093Victor, J.G., Torkelson, J.M., (1987) Macromolecules, 20, p. 2241Victor, J.G., Torkelson, J.M., (1988) Macromolecules, 21, p. 3490Bohlen, J., Kirchheim, R., (2001) Macromolecules, 34, p. 4210Scmitz, H., Muller-Plathe, F., (2000) J. Chem. Phys., 112, p. 104
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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