In this guided-inquiry style laboratory the fluorescence spectra of pyrene monomers and excimers are used to explore the relationship between spectroscopy and thermodynamic parameters.  Students are introduced to the concept of excimers and begin the lab with an examination of the energy diagrams for the pyrene excimer and for pyrene monomer-monomer interactions.  This initial consideration of the energy diagram guides students as they develop a set of fluorescence experiments that enable them to explore the effects of concentration and temperature on the resulting spectra.  Once a set of spectra has been collected at various temperatures, students use their data to calculate thermodynamic parameters of the system.  The data analysis includes challenging but appropriate manipulation of equations and graphical methods to determine the enthalpy and entropy of pyrene excimer formation. Students also calculate the monomer-monomer repulsion energy and dimer binding energy, parameters which relate directly to the energy diagram that was initially analyzed in the opening exercise of the experiment.<br/>

Guided-inquiry approach for relating the fluorescence spectrum of the pyrene excimer to its thermodynamic properties<br />

249th National Meeting (2015)

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