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Course Material on the Web. Lecture 1 at http://www.zfch.amu.edu.pl/publikacje.html http://www.zfch.amu.edu.pl/Lecture 1.ppt http://150.254.84.227/HUG (uncorrected version) Lecture 3 (seminar by Isvan Robel) at http://www.nd.edu/~pkamat/femto.html Lecture 4 material at
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Course Material on the Web • Lecture 1 at http://www.zfch.amu.edu.pl/publikacje.html http://www.zfch.amu.edu.pl/Lecture 1.ppt http://150.254.84.227/HUG (uncorrected version) • Lecture 3 (seminar by Isvan Robel) at http://www.nd.edu/~pkamat/femto.html • Lecture 4 material at http://www.rcdc.nd.edu/compilations/Tta/tta.pdf
Lecture 3 Pump-Probe Femtosecond Laser Isvan Robel Physics Graduate student at Notre Dame
Review of Lecture 1 • Excited states and free radicals act like distinct chemical species. • However, it is important to characterize their time-dependence in order to utilize their energy content.
ISC IC excited singlet state S1 S1 singlet ground state S0 T1 ISC fluorescence vibrational relaxation (heat) phosphorescence excited triplet state S0 T1 Review of Lecture 1 Jabłonski - diagram State Picture Orbital Picture
Review: Robinson-FroschRate of Radiationless Transitions dP(nm)/dt = (42/h) |Vmn|2 FC (Em) • Three factors • Electronic matrix element • Franck-Condon factors • Density of final states
Review: Franck-Condon Effect Sn S1 S0
Review: El-Sayed’s Rule • Selection Rule for Intersystem Crossing • Transitions between a singlet state and a triplet state of the same orbital configurations are slower than that between states having different orbital configurations. • Examples, ISC transition 1n,* 3,* is much faster than 1,* 3,*
Characteristics ofRadiationless Transitions • Kasha’s Rule • El-Sayed’s Rule • Deuterium Effect • Wavelength Independence of Luminescence • Energy Gap Law • Competitive First-Order Kinetics
Lecture 2 • Part 1: Fluorescence Lifetimes using Stroboscopic Method • 10-minute break • Part 2: Fluorescence Lifetimes using Time-Correlated Single-Photon Counting TC-SPC
Stroboscopic Method • Aleksander Siemiarczuk, et al. Reviews of Scientific Instruments63, 1710-1716 (1992) • Commercial Instrumentation by PTI
Sample & Excitation Lamp PMT Sample Fluorescence Monochromator Excitation Monochromator
Photomultiplier Tubes (PMT) h Photocathode of PMT e Dynodes of PMT Ne Anode of PMT
Pulsing the PMT Detection Photocathode of PMT Dynodes of PMT Anode of PMT