Fundamentals of Photophysics, Photochemistry, and Photobiology

Abstract

This chapter provides an introduction to the photophysical and photochemical fundamentals that should represent a useful scientific background for applicants of photodynamic therapy (The references given in the abstract provide some access to generally recommended textbooks or reviews of the various areas.). First, the absorption of light and the basics of spectrophotometry (Parson in Modern Optical Spectroscopy. With exercises and examples from biophysics and biochemistry. Springer-Verlag, Berlin Heidelberg, 2007; Burgess and Frost in Standards and best practice in absorption spectrometry. Blackwell Science, London, 1999; Gore in Spectrophotometry and Spectrofluorimetry. Oxford University Press, Oxford, 2000) are dealt with, including a theoretical background to understand absorption spectra. Then follows a survey of photophysical processes with the characteristic pathways of radiationless and radiative decay of electronically excited states (Lakowicz in Principles of fluorescence spectroscopy. Springer Science+Business Media, New York, 2006), electronic energy transfer and a brief introduction into singlet oxygen (Schweitzer and Schmidt, Chem Rev 103:1685–1757, 2003). The photochemistry part (Turro et al. in Principles of molecular photochemistry: an introduction. University Science Books, Sausalito, 2009; Klan and Wirz in Photochemistry of organic compounds. From concept to practice. Wiley, Chichester, 2009; Stochel et al. in Bioinorganic Photochemistry, Wiley, Chichester, 2009) explains the concept of photoreactions as excited state chemistry and changes of chemical properties and chemical reactivity as a consequence of the modified electronic structure in the excited state. Elementary processes dealt with comprise photoinduced electron transfer (Kavarnos in Fundamentals of photoinduced electron transfer. VCH Publishers, New York, 1993), excited state proton transfer and cis/trans-photoisomerization. Photobiological aspects, such as photosynthesis and vision (Kohen et al. in Photobiology. Academic Press, San Diego, 1995; Batschauer in Photoreceptors and Light Signaling. Comprehensive Series in Photochemical and Photobiological Sciences. The Royal Society of Chemistry, Cambridge, 2003), are briefly outlined.