Photophysics of Aromatic Molecules

Transcription

1 Photophysics of Aromatic Molecules John B. Birks Reader in Physics, University of Manchester WILEY - INTERSCIENCE a division of John Wiley & Sons Ltd London New York Sydney Toronto

2 itffiskfti' i 1. Excited states of aromatic molecules 1.1 Electronic structure. 1.2 Molecular structure. 1.3 The PFEO model Selection rules 1.5 Other theoretical modeis Tables '"!". 1.6 References Photophysical processes 2.1 Introduction. '".'...;., ;,?, ; Unimolecular processes Biphotonic processes. : ' Bimolecular processes... "." Rate parameters. ;! "; ;! :i Tables v : j :. : References... i Absorption 3.1 Vibronicstates.' : t v. r.., Hot bands ; The extinction coefficient ,3.4 The Born-Oppenheimer approximation.. -'4- ^ The Einstein coefficients...:..,.; Transition moments...;;;. ;. :.; Oscillator strengths. w-wri ru u >l.-i :. v The Franck-Condon principle. 'j.. I Absorption spectra.... *.. 54 ix

3 3.10 Flash photolysis and S! S p absorption 3.11 Multiphotonic absorption. Tables References Fluorescence 4.1 Thefluorescencespectrum 4.2 The mirror symmetry relation 4.3 The radiative lifetime. 4.4 Thefluorescenceparameters. 4.5 Competing bimolecular processes 4.6 Determination offluorescencelifetimes. ':vi;tt.vh 4.7 Determination offluorescencespectra and quantum yields 4.8 Experimental tests of the radiative lifetime relations. 4.9 Fluorescence lifetimes and quantum efficiencies Fluorescence spectra Scintillator solutes..,..:...' Influence of environment on fluorescence and absorption spectra.... Tables , 4.13 References Radiationless transitions 5.1 Singlet-singlet internal conversion 5.2 Intersystem crossing 5.3 Triplet-triplet internal conversion 5.4 Internal quenching of fluorescence 5.5 T, S 0 intersystem crossing. 5.6 The theory of radiationless transitions 5.7 Ti - S 0 intersystem crossing: Franck-Condon factors 5.8 The isotope rule 5.9 T, S 0 intersystem crossing: comparison of theory with experiment 5.10 Energy gaps... ;. > -f i 5.11 S! S 0 internal conversion v ;. v.;« S 2 S! internal conversion.. ;.. ' ;;.-.?, 5.13 Dual luminescences...>. (> Internal conversion in benzene and its derivatives Tables ; References ; ^

4 xi 6. The triplet State 6.1 Triplet and phosphorescence parameters The determinationof triplet quantum yields Triplet quantumyields...,, >..,.., Spectrophosphorimetry i 6.5 The determination of phosphorescence quantum efficiencies Phosphorescence lifetimes, quantum efficiencies and spectra 207 < 6.7 Theheavyatomeifect Singlet-triplet absorption Triplet-triplet absorption _.., " Triplet energy leyels Assignment of the electronic states of the polyacenes Spin-orbit interaction Singlet-triplet intersystem crossing Triplet-triplet internal conversion and fluorescence Photo-ionization.., Vapoursof benzene and its derivatives The triplet State ofbenzene. \.. v. 248 Tables ;.,. : References.. ^T,.' Excimers 7.1 Excimer fluorescence Photostationary reaction kinetics.., Transient reaction kinetics Determinationof rate parameters Hightemperaturebehaviour., Frequency factors and activation energies y, 7.7 Diffusion-controlled processes...,, Excimerfluorescencein Solution Excimerfluorescenceofcrystals Photodimer and excimer formation Sandwich dimers , Intramolecular excimer fluorescence The excimer potential energy diagram, r; 7.14 Theoryof excimer states : 7.15 Determination of excimer interaction potential Photophysical processes in excimers.... ;. 335 ;-; Excimer formation processes Excimer phosphorescence..! Tables >: References. 370

5 xii 8. Delayed luminescence 8.1 Typesof delayed luminescence.. : : E-type delayed fluorescence ; ^ ' ; : ; ;_ ^, 8.3 Fluorescence of mixed molecular species Triplet-triplet interaction in concentrated fluid Solutions 8.5 Triplet-triplet interaction in dilute fluid Solutions. 8.6 P-type delayedfluorescencein fluid Solutions. 8.7 P-type delayedfluorescencein rigid Solutions. f ;; 8.8 Mechanism of triplet-triplet interaction.. ; 8.9 The determination of total triplet quantum yields : V'! 8.10 Recombinationluminescence... : ">: ' ; - Table8.1. \ '"- *«"' "i l: '---p -1-'0 ; "^»ä»; ' 8.11 References.... ;!.. v^ 9. Molecular complexes and exciplexes 9.1 Donor-acceptorcomplexes.. n Charge-transfer absorption. ; :. 9.3 Kineticsof DA complexes.;. * 9.4 Contact CT absorption Luminescence of DA complexes 9.6 Exciplexes Mixed excimers Fluorescence of exciplexes.) 9.9 Impurity quenching of fluorescence Photochemical quenching of fluorescence 9.11 Kineticsof impurity quenching Impurity quenching of triplet states i Tables V V. i '; 9.13 References.... ".'. 10. Interactions with oxygen and nitric oxide 10.1 Oxygen and nitric oxide 10.2 Contact CT absorption Enhanced S 0 -T! absorption 10.4 Quenching by oxygen Photoperoxidation studies 10.6 Quenching by nitric oxide 10.7 Static quenching. ; 10.8 Kinetics offluorescencequenching by oxygen 10.9 Collisionalandexchangequenching.. ^ Tables References

6 . xiii 11. Energy migration and transfer 11.1 Migration and transfer processes Radiative migration and transfer Exciton states in crystals 11.4 Singlet exciton migration and transfer in crystals 11.5 Triplet-triplet energy transfer in Solution 11.6 Triplet exciton migration and transfer in mixed crystals 11.7 Triplet-triplet interactions in mixed crystals 11.8 Triplet excitons in pure crystals Singlet-singlet energy transfer in Solution Influenceofdiffusionon energy transfer Excitation migration and transfer in aromatic liquid Solutions Other intermolecular transfer processes Intramolecular energy transfer Photochemistry and photobiology.... Tables References Postscript 625 Tables References Table Index of Compounds Table Index of Processes and Parameters 660 Author Index. 669 Subject Index..681