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Brown, Frederick C. Stacy, William Turlay 2011-07-26T18:51:49Z 2011-07-26T18:51:49Z 10000-01-01 1970 The delayed fluorescence emitted by both crystalline anthracene and chlorophyll a in algae is studied. In the case of crystalline anthracene, the blue light-excited delayed fluorescence is used to study the temperature dependence of monomolecular intersystem crossing. The associated rate constant k is found to obey an equation of the form [equation] where E = 900 ± 100 cm and k2/k1 = 800 + 200. A calculation of the relevant Franck-Condon factors using the method developed by Siebrand yields good agreement with the experimental value of k2/k1 . At temperatures below 90 o K, the temperature dependence of the delayed fluorescence intensity exhibits a pronounced maximum which is qualitatively explained in terms of triplet exciton traps. The delayed fluorescence emitted by algae is explained in terms of a triplet exciton fusion model in which the production of triplets is mediated by a photochemical reaction center (photosystem II). The evidence for this model is based on an extensive study of the time dependence of the luminescence decay and the observation that, at low light levels, the delayed fluorescence' intensity is proportional to the square of the excitation intensity. Direct proof in the form of a magnetic field effect on the delayed fluorescence was not obtained. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-07-26T18:51:49Z No. of bitstreams: 1 1970_stacy.pdf: 3337087 bytes, checksum: 0e51896044c194825acbf02be65ea1ec (MD5) Made available in DSpace on 2011-07-26T18:51:49Z (GMT). No. of bitstreams: 1 1970_stacy.pdf: 3337087 bytes, checksum: 0e51896044c194825acbf02be65ea1ec (MD5) Previous issue date: 1970 Restriction data tranferred 2014-07-01T11:33:21-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-07-26T18:51:49Z Item is restricted indefinitely. Thesis U of I Only 6056282 http://hdl.handle.net/2142/25841 en 1970 William Turlay Stacy delayed fluorescence radiationless transitions anthracene algae chlorophyll Delayed fluorescence as a probe of radiationless transitions in anthracene and algae Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.