{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,14]],"date-time":"2025-10-14T06:47:49Z","timestamp":1760424469864},"reference-count":65,"publisher":"AIP Publishing","issue":"15","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2003,4,15]]},"abstract":"<jats:p>Poly[9,9-di(ethylhexyl)fluorene] was studied by steady-state and time-resolved fluorescence techniques in solution in cyclohexane, methylcyclohexane, tetrahydrofuran, and decalin over the temperature range from 343 to 77 K. A decrease in temperature leads to a decrease in the inhomogeneous broadening of the emission band. Fluorescence decays were biexponential, consistent with a two-state model involving two different polymer conformers. Global analysis of the time profiles of luminescence collected at different emission wavelengths shows a long decay-time of 371.5\u00b11.5\u2009ps, which is temperature and solvent independent. The second shorter time (29\u00b13\u2009ps at 313 K and 100\u00b13\u2009ps at 233 K in methylcyclohexane) appears as a decay-time at the onset of the emission spectrum and as a risetime at longer wavelengths. Whilst the slow process was independent of temperature, the fast process showed Arrhenius type behavior, with an activation energy value of 0.10 eV found in both methylcyclohexane and decalin solutions. However, the risetime in the more viscous decalin was longer than that in methylcyclohexane. The observed behavior is interpreted in terms of fast conformational relaxation of the initially excited polymer, leading to a more planar conjugation segment.<\/jats:p>","DOI":"10.1063\/1.1560939","type":"journal-article","created":{"date-parts":[[2003,4,3]],"date-time":"2003-04-03T23:04:16Z","timestamp":1049411056000},"page":"7119-7126","update-policy":"http:\/\/dx.doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":74,"title":["Picosecond conformational relaxation of singlet excited polyfluorene in solution"],"prefix":"10.1063","volume":"118","author":[{"given":"Fernando B.","family":"Dias","sequence":"first","affiliation":[{"name":"Instituto de Tecnologia Qu\u0131\u0301mica e Biol\u00f3gica (ITQB), Ap. 127, P2781-901\u2009Oeiras, Portugal"}]},{"given":"Ant\u00f3nio L.","family":"Ma\u00e7anita","sequence":"additional","affiliation":[{"name":"Instituto de Tecnologia Qu\u0131\u0301mica e Biol\u00f3gica (ITQB), Ap. 127, P2781-901\u2009Oeiras, Portugal"},{"name":"Instituto Superior T\u00e9cnico (IST), Departamento de Qu\u0131\u0301mica, Lisboa, Portugal"}]},{"given":"J.","family":"Seixas de Melo","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u0131\u0301mica, Universidade de Coimbra, P3004-535\u2009Coimbra, Portugal"}]},{"given":"Hugh D.","family":"Burrows","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u0131\u0301mica, Universidade de Coimbra, P3004-535\u2009Coimbra, Portugal"}]},{"given":"Roland","family":"G\u00fcntner","sequence":"additional","affiliation":[{"name":"Polymerchemie, Institut f\u00fcr Physikalische und Theoretische Chemie, Universit\u00e4t Potsdam, D-14476\u2009Golm, Germany"}]},{"given":"Ulli","family":"Scherf","sequence":"additional","affiliation":[{"name":"Polymerchemie, Institut f\u00fcr Physikalische und Theoretische Chemie, Universit\u00e4t Potsdam, D-14476\u2009Golm, Germany"}]},{"given":"Andrew P.","family":"Monkman","sequence":"additional","affiliation":[{"name":"Department of Physics, University of Durham, Durham\u2009DH1\u20093LE, United Kingdom"}]}],"member":"317","reference":[{"key":"2024020607592562100_r1","doi-asserted-by":"crossref","first-page":"L1941","DOI":"10.1143\/JJAP.30.L1941","volume":"30","year":"1991","journal-title":"Jpn. 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