Experimental Techniques for Excited State Characterisation

  • J. Sérgio Seixas de Melo
  • João Pina
  • Fernando B. Dias
  • António L. Maçanita


The characterisation of the excited state of a molecule implies the determinations of the different quantum yields and lifetimes. Additionally, complex kinetic systems are frequently observed and need to be solved. In this contribution, we give our particular way of studying systems of organic molecules where we describe how a quantum yield of fluorescence (in fluid or rigid solution, or in film), phosphorescence, singlet oxygen and intersystem crossing can be experimentally determined. This includes a brief description of the equipments routinely used for these determinations. The interpretation of bi- and tri-exponential decays (associated with proton transfer, excimer/exciplex formation in the excited state) with the solution of kinetic schemes (with two and three excited species), and consequently the determination of the rate constants is also presented. Particular examples such as the excited state proton transfer in indigo (2-state system), the acid–base and tautomerisation equilibria in 7-hydroxy-4-methylcoumarin (3-state system), together with the classical examples of intramolecular excimer formation in 1,1’-dipyrenyldecane (2-state system) and 1,1’-dipyrenylpropane (3-state system) are given as illustrative examples.


Quantum Yield Triplet State Fluorescence Quantum Yield Fluorescence Decay Maximum Entropy Method 
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© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • J. Sérgio Seixas de Melo
    • 1
  • João Pina
    • 1
  • Fernando B. Dias
    • 2
  • António L. Maçanita
    • 3
  1. 1.Department of ChemistryUniversity of CoimbraCoimbraPortugal
  2. 2.OEM Research Group, Department of PhysicsDurham UniversityDurhamUK
  3. 3.Centro de Química EstruturalInstituto Superior Técnico (IST)LisbonPortugal

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