Two-Photon Excited Fluorescence Depolarisation [Elektronisk resurs] Experimental and Theoretical Development
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Ryderfors, Linus, 1977- (författare)
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Mukhtar, Emad (preses)
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Johansson, Lennart B.-Å. (preses)
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Levine, Yehudi K. (opponent)
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Uppsala universitet Teknisk-naturvetenskapliga vetenskapsområdet (utgivare)
- Publicerad: Uppsala : Universitetsbiblioteket, 2008
- Engelska 78
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Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 1651-6214 ; 552
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Sammanfattning
Ämnesord
Stäng
- We have studied fundamental aspects of time-resolved two-photon excited fluorescence depolarisation. The thesis presents experimental as well as theoretical progress. We show that a multi-photon induced instrumental response function obtained from a suspension of gold nanoparticles is appropriate for the analysis of two-photon excited fluorescence decays obtained using time-correlated single photon counting detection. Theoretical expressions have been derived for the fluorescence anisotropy decay obtained upon two-photon excitation of various molecular systems in liquid solutions: a) an anisotropic rigid rotor that undergoes rotational diffusion in the presence of ultrafast unresolved restricted reorientations, e.g. librations. b) a molecular group covalently attached to a stationary macromolecule, and undergoing local reorientation in a uniaxial ordering potential. A new approach to the analysis of two-photon excited fluorescence depolarisation experiments was developed, which combines data obtained by using linearly and circularly polarised excitation light, in a global manner. In the analysis, knowledge about unresolved reorientations was obtained from one-photon excitation studies of the corresponding systems. By means of this procedure it has been possible to obtain quantitative information about the molecular two-photon absorption tensor for perylene and two of its derivatives. Thereby the symmetry of the final excited and intermediate vibronic states could be assigned. The analysis reveals that the two-photon transition studied with the 800 nm laser exhibits mixed character. An important finding from the experiments was that the two-photon absorption tensor appears to be solvent dependent. Furthermore, the thesis presents the first theoretical treatment of two-photon excited donor-donor energy migration in the presence of molecular reorientation and which applies the extended Förster theory. Explicit expressions for molecules that belong to the point groups D 2h , D 2 and C 2v are given. Preliminary experiments are finally also reported on a two-photon excited donor-donor energy migration system consisting of a bisanthryl-bisteroid.
Ämnesord
- Natural Sciences (hsv)
- Physical Sciences (hsv)
- Atom and Molecular Physics and Optics (hsv)
- Naturvetenskap (hsv)
- Fysik (hsv)
- Atom- och molekylfysik och optik (hsv)
- NATURAL SCIENCES (svep)
- Physics (svep)
- Atomic and molecular physics (svep)
- Chemical physics (svep)
- NATURVETENSKAP (svep)
- Fysik (svep)
- Atom- och molekylfysik (svep)
- Kemisk fysik (svep)
Genre
- government publication (marcgt)
Indexterm och SAB-rubrik
- Two-photon excitation
- Fluorescence
- Fluorescence depolarisation
- Fluorescence anisotropy
- Time-correlated single photon counting
- Gold nanoparticles
- Rotational diffusion
- Excited state symmetry
- Extended Förster theory
- Orientation correlation functions
- Donor-donor energy migration (DDEM)
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