24
1 Introduction to Photochemistry
1.4 The chlorofluorocarbons are photodissociated in the stratosphere only when
they reach an altitude where UV light with sufficiently short wavelengths is present.
CCl 3 CF 3 does not absorb significantly at λ > 220 nm. The C-Cl dissociation energy
is about 330 kJ/mol. Are short wavelengths needed for the photodissociation because
of the absorption spectrum of CCl 3 CF 3 or because of the C-Cl bond strength?
1.5 Compute the lifetimes of T 1 and S 1 of benzophenone and its phosphorescence
quantum yield. The same for naphthalene, with the addition of its fluorescence quantum yield. Use the lifetime of each process indicated in Fig. 1.2 (remember that the
inverse of a lifetime is the rate constant of the process).
1.6 In the example of photochromic reaction kinetics discussed in Sect. 1.6.3, suppose the experiment with high irradiance is repeated at a higher temperature, so that
K A→B increases by 80% and K B→A by 50%. Based on the data that can be inferred
from Fig. 1.5, which fraction of B is expected at 150 s?
References
1. Wayne, R.P.: Principles and Applications of Photochemistry. Oxford University Press, Oxford
(1988)
2. Wardle, B.: Principles and Applications of Photochemistry. Wiley, Chichester (2009)
3. Turro, N.J., Ramamurthy, V., Scaiano, J.C.: Modern Molecular Photochemistry of Organic
Molecules. University Science Books, Sausalito (2010)
4. Balzani, V., Ceroni, P., Juris, A.: Photochemistry and Photophysics: Concepts, Research, Applications. Wiley, Chichester (2014)
5. Rohatgi-Mukherjee, K.K.: Fundamentals of Photochemistry. New Age International, New
Delhi (2017)
6. Cohen-Tannoudji, C., Dupont-Roc, J., Grynberg, G.: Atom-Photon Interactions: Basic Processes and Applications. Wiley-VCH, Weinheim (2004)
7. Wayne, R.P.: Chemistry of the Atmospheres. Oxford University Press, Oxford (2000)
8. Favero, L., Granucci, G., Persico, M.: Surface hopping investigation of benzophenone excited
state dynamics. Phys. Chem. Chem. Phys. 18, 10499–10506 (2016)
9. Lamola, A.A., Leermakers, P.A., Beyers, G.W., Hammond, G.S.: Intramolecular electronic
energy transfer between nonconjugated chromophores in some model compounds. J. Am.
Chem. Soc. 87, 2322–2332 (1965)
10. Gauglitz, G., Hubig, S.: Chemical actinometry in the UV by azobenzene in concentrated solution: a convenient method. J. Photochem. 30, 121–125 (1985)
1 Introduction to Photochemistry
1.4 The chlorofluorocarbons are photodissociated in the stratosphere only when
they reach an altitude where UV light with sufficiently short wavelengths is present.
CCl 3 CF 3 does not absorb significantly at λ > 220 nm. The C-Cl dissociation energy
is about 330 kJ/mol. Are short wavelengths needed for the photodissociation because
of the absorption spectrum of CCl 3 CF 3 or because of the C-Cl bond strength?
1.5 Compute the lifetimes of T 1 and S 1 of benzophenone and its phosphorescence
quantum yield. The same for naphthalene, with the addition of its fluorescence quantum yield. Use the lifetime of each process indicated in Fig. 1.2 (remember that the
inverse of a lifetime is the rate constant of the process).
1.6 In the example of photochromic reaction kinetics discussed in Sect. 1.6.3, suppose the experiment with high irradiance is repeated at a higher temperature, so that
K A→B increases by 80% and K B→A by 50%. Based on the data that can be inferred
from Fig. 1.5, which fraction of B is expected at 150 s?
References
1. Wayne, R.P.: Principles and Applications of Photochemistry. Oxford University Press, Oxford
(1988)
2. Wardle, B.: Principles and Applications of Photochemistry. Wiley, Chichester (2009)
3. Turro, N.J., Ramamurthy, V., Scaiano, J.C.: Modern Molecular Photochemistry of Organic
Molecules. University Science Books, Sausalito (2010)
4. Balzani, V., Ceroni, P., Juris, A.: Photochemistry and Photophysics: Concepts, Research, Applications. Wiley, Chichester (2014)
5. Rohatgi-Mukherjee, K.K.: Fundamentals of Photochemistry. New Age International, New
Delhi (2017)
6. Cohen-Tannoudji, C., Dupont-Roc, J., Grynberg, G.: Atom-Photon Interactions: Basic Processes and Applications. Wiley-VCH, Weinheim (2004)
7. Wayne, R.P.: Chemistry of the Atmospheres. Oxford University Press, Oxford (2000)
8. Favero, L., Granucci, G., Persico, M.: Surface hopping investigation of benzophenone excited
state dynamics. Phys. Chem. Chem. Phys. 18, 10499–10506 (2016)
9. Lamola, A.A., Leermakers, P.A., Beyers, G.W., Hammond, G.S.: Intramolecular electronic
energy transfer between nonconjugated chromophores in some model compounds. J. Am.
Chem. Soc. 87, 2322–2332 (1965)
10. Gauglitz, G., Hubig, S.: Chemical actinometry in the UV by azobenzene in concentrated solution: a convenient method. J. Photochem. 30, 121–125 (1985)