1. “Cool Light”

2. Three types of “Cool Light” Fluorescence: Fluorescence: higher energy radiation is absorbed by a species and stored Phosphorescence: Phosphorescence: light is absorbed by a molecule which becomes excited to a higher singlet state. Chemiluminescence: Chemiluminescence: the energy required to emit light comes from the energetics of the chemical reaction.

3. Chemiluminescence The non-thermal production of visible light by a chemical reaction. Occurs when an energy releasing reaction produces a molecule in an electronically excited state, as that molecule returns to the ground state it releases its energy as a photon of light. Rigid and Aromatic molecules

4. Glow Stick Shows temperature dependence of chemical reaction involving chemiluminescence Shows temperature dependence of chemical reaction involving chemiluminescence Energy transfer between an intermediate formed in the reaction between phenyl oxalate ester and hydrogen peroxide Energy transfer between an intermediate formed in the reaction between phenyl oxalate ester and hydrogen peroxide

5. Electronically Excited State

6. Excited State The wavelength of light emitted by a molecule is related to the energy of its excited state. E=hc/λ h= Plank’s constant λ= wavelength of emitted light(m) c= speed of light E= energy difference between emissive excitedstate and ground state

7. Bioluminescence The production of chemiluminescence by living organisms The production of chemiluminescence by living organisms

8. Direct Chemiluminescence A* → A + light When the emissive excited state molecules are produced directly by the reaction mechanism When the emissive excited state molecules are produced directly by the reaction mechanism

9. Sensitized Chemiluminescence A* + B → A + B* When an acceptor molecule receives excitation energy from an excited state species, and releases the energy as a photon of light.

10. Applications Latent fingerprints Blood/fluid tests Entertainment DNA testing Spectroscopy Pharmaceutical Industry (analysis and quality control)

11. Oxidation of luminol 1 st report of chemiluminescence from luminol was made by Albrecht in 1928

12. References http://agrippina.bcs.deakin.edu.au/bcs_courses/forensic/ Chemical%20Detective/index.htm http://agrippina.bcs.deakin.edu.au/bcs_courses/forensic/ Chemical%20Detective/index.htm http://www.shsu.edu/%7Echm_tgc/JPPdir/JPP1999/ http://www.shsu.edu/~chm_tgc/chemilumdir/chemilumine scence2.html http://www.shsu.edu/~chm_tgc/chemilumdir/chemilumine scence2.html J. Org. Chem., Vol. 35, No. 7, 1970 http://dsc.discovery.com/fansites/onthecase/toolbox/tool _01.html http://dsc.discovery.com/fansites/onthecase/toolbox/tool _01.html http://www.deakin.edu.au/forensic/Chemical%20Detectiv e/Luminol_test.htm http://www.deakin.edu.au/forensic/Chemical%20Detectiv e/Luminol_test.htm Shakhashiri, Bassam; Chemical Demonstrations. Vol. 1 The University Of Wisconsin Press, 1983