ELSEVIER Solar Energy Materials and Solar Cells 32 (1994) 219-220

s o ~ r n ~ w ~ lind .Stair ellis

B o o k R e v i e w s

The Photosystems: Structure, Function and Molecular Biology Edited by J. Barber, (Elsevier Science Publishers, Amsterdam, 1992), ISBN 0-444-89440-3 (hbk.); 558 pages; price US$243.00.

Much recent research in electronics is now focused on what is being called nanotechnology. In reading the 1 lth volume of Topics in Photosynthesis, scientists and engineers working in the field of solar energy would gain an appreciation for some of the most successful solar powered molecular machines on Earth. The book begins with an introduction, by R. Cogdell and R. Malkin, to plant and bacterial photosystems. Of particular interest is the illustration and description of the bacterial phototosynthetic reaction center. It illustrates the marvellous orienta- tional relationship between the bacterial chlorophyll molecule, carotenoids and the pheophytin electron acceptors within the cell membrane. Another aspect of interest to those in solar conversion is the speed of this electron transfer, which on the order of 1-200 x 10-12 seconds. The next chapter postulates that even though photosynthesis is a non-equilibrium system, the maximum conversion efficiencies must be described by the first and second laws of thermodynamics. Following in the tradition of researchers such as P.T. Landsberg, the approach is to consider the entropy associated with the absorption of light, and to define an "effective" temperature for use in efficiency equations. My critique is that little mention is made to more recent methods pioneered by Ross, Haught and Bolton, which bypass the direct calculation of the entropy involved, but instead form a detailed balance between solar input and luminescence output. What this chapter has made clear though is that the absorbance found in photosynthesis, and the input spectrum need to be carefully defined before a adequate assessment of the thermodynamics can be made. Energy transfer and trapping in Photosystem II, PSII, is described in the next chapter. An extremely helpful diagram outlines the molecular energy levels and associated optical absorption spectrum for Chlorophyll a. Presented is that the long lived triplet state of Chl a is important role for in vitro reactions, while the lowest excited singlet state is important for redox reactions within the living photosynthetic reaction center. Other important topics covered in this book include, hole burning a quantum mechanical treatment of electron and exciton transfer, the Mn oxygen evolution center of PS II, thermoluminescence, photoinhibition, and the molecular biology and structural engineering of PSI and

0927-0248/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0 9 2 7 - 0 2 4 8 ( 9 3 ) E 0 1 18-W

220 Book Reviews / Solar Energy Materials and Solar Cells 32 (1994) 219-220

PSII. Although this book was written for the molecular plant biologist working in this field, I recommend it to those interested in solar energy materials who wish an in-depth look at the current understanding of photosynthesis.

Greg Smestad

Photocatalytic Purification and Treatment of Water and Air: Proceedings of the 1st International Conference on Ti02 Photocatalytic purification and Treatment of Water and Air, London, ON, Canada, 8-13 November 1992 Edited by D. Ollis, North Carolina State University, Raleigh, NC, USA and H. Al-Ekabi, Nutech Environmental, London, ON, Canada

Trace Metals in the Environment Volume 3 (Elsevier Science Publishers, Amsterdam, 1993), ISBN 0-444-89855-7; 820 pages; price: Dfl. 450.00 (US $257.25)

This volume comprises the results of the 1st international conference examining the status and promise of the emerging area of photochemistry. It includes the views of engineers and chemists from industry, government and academia, covering such areas as: comparison with other competitive technologies; integration with complementary processes (such as ultrafiltration and biological treatment); trans- fer of research results into development and application activities; and economics and optimization of photocatalysis as the energizing themes for the 1990s and beyond. The book will be of great interest to environmental scientists and engi- neers; public works, highways and utilities engineers; photoehemists; and to all those involved in the many challenges of water and air punfication remediation, detoxification and deodorization.