Question 1.The fluorescence intensity of 9,10-dicyanoanthracene (DCA) was measured as a function of concentration of hexamethylbenzene (HMB) in acetonitrile. The data are given in the file below. Assume that the rate constant for reaction between the excited DCA and HMB is diffusion controlled. What is the lifetime of the DCA excited singlet state under the conditions of the experiment? The first column of the data is emission intensity in arbitrary units, the second column is the HMB concentration.
Quenching Data File.

Question 2. What is the exothermicity of the following reactions, in units of kcal/mol? (hint, you will have to look up some excited singlet and triplet energies and oxidation and reduction potentials in a reference book. I suggest The Handbook of Photochemistry. There is a copy of this book in my lab) For the electron transfer reactions, ignore the coulomb terms when calculating the energies of the electron transfer products. In essence, this is saying, assume that you are in acetonitrile solvent).

Question 3. The decay of the luminescence of singlet oxygen in water was measured as a function of time. The data is given in the file below. What is the lifetime of the singlet oxygen under these conditions?
Singlet Oxygen Decay Data.

Question 4. Irradiation of pyrene in the presence of dimethylaniline results in the emission spectra shown below. The spectra are different at different times. Assign to the main features in these absorption spectra.

Question 5. Irradiation of the ketone below results in radical and disproportionation products resulting from triplet state cleavage and decarbonylation of the intermediate benzoyl radical. Give a mechanism showing formation of all of the possible IN CAGE products, i.e. not the products from those radicals that separate from the initial geminate pair.

Question 6. A tetrasulfonated porphyrin exhibits an absorption spectrum that changes depending upon conditions, as shown below. The tetraanion and dianion salts in buffer have absorption bands indicated by A and B respectively. In micellar solution the tetraanion exhibits aggregate absorption band C and the dianion band D. Assign the bands C and D to either H- or J-aggregates.

Question 7. Give the mechanism of the following reaction (hint, look in your notes).

Question 8. Give the excitation energies of perylene (top spectra) and quinine (lower spectra) in units of kcal/mol (hint, use a ruler if necessary!).

None of these questions should take a long time to do. if you spend more than ca. 20 minutes on any question, please stop, and come and see me and I will help you.