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What is Fluorescence?

What is Fluorescence?. What is Fluorescence?. A type of electronic spectroscopy, that is, it involves excitation of electrons— energy absorption to an excited state — followed by emission of a smaller energy as radiation. Fluorescence and Phosphorescence are two types of Luminescence .

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What is Fluorescence?

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  1. What is Fluorescence?

  2. What is Fluorescence? A type of electronic spectroscopy, that is, it involves excitation of electrons—energy absorption to an excited state— followed by emission of a smaller energy as radiation. Fluorescence and Phosphorescence are two types of Luminescence. http://elchem.kaist.ac.kr/vt/chem-ed/spec/molec/mol-fluo.htm

  3. What is Fluorescence? S refers to ‘singlet’ and T to ‘triplet’ states. The S0 state is the ground state and the subscript numbers, S1 and S2 , identify individual excited states. Link to Simulation spectrometer: http://terpconnect.umd.edu/~toh/models/Fluorescence.html

  4. What is Fluorescence? Sample cell excitation monochromator Xe lamp Emission monochromator photodetector

  5. Why is Fluorescence useful in DNA (and other biochemical) Studies? • Fluorescence generally is much more sensitive to the environment of • the chromophore than is light absorption. • Fluorescence is a useful technique for following the binding of ligands • or conformational changes. • The sensitivity of fluorescence is a consequence of the relatively long • time a molecule stays in an excited singlet state before de-excitation. • Absorption is a process that is over in 10-15 sec, a time scale where the molecule and its environment are effectively static. • In Fluorescence , during the 10-9 to 10-8 sec that a singlet remains excited, all kinds of processes can occur, including protonation or deprotonation reactions, solvent-cage relaxation, local conformational changes, and any processes coupled to translational or rotational motion.

  6. What is the connection between Fluorescence and DNA Photocleavage? {Ru(bpy)2(L)2+}* Excited state {Ru(bpy)2(L)2+}* Excited state + hn Ru(bpy)2(L)2+ Ground state Ru(bpy)2(L)2+ Ground state

  7. What is the connection between Fluorescence and DNA Photocleavage? O=O {Ru(bpy)2(L)2+}* Excited state MLCT, de- p* orbital 3O2triplet state, T “triplet energy transfer" 1O2singlet state, S O=O “Ru(bpy)2(L)2+“ Relaxed state Ru(bpy)2(L)2+ Ground state

  8. What is the connection between Fluorescence and DNA Photocleavage? AT TA CG GC AT CG {Ru(bpy)2(L)2+}* 1O2 + hn 3O2 AT TA CoxG GC AT CG “Ru(bpy)2(L)2+“ Relaxed state Ru(bpy)2(L)2+ Ground state

  9. What is the connection between Fluorescence and DNA Photocleavage? Oxidized Guanine bases AT TA CG GC AT CG 1O2 3O2 AT TA CoxG GC AT CG

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