Photochemistry: Volume 2 (Specialist Periodical Reports, Band 2) - Hardcover

Hardcover

ISBN 10: 085186015X ISBN 13: 9780851860152

Verlag: Royal Society of Chemistry, 1971

Inhaltsangabe

The breadth of scientific and technological interests in the general topic of photochemistry is truly enormous and includes, for example, such diverse areas as microelectronics, atmospheric chemistry, organic synthesis, non-conventional photoimaging, photosynthesis, solar energy conversion, polymer technologies, and spectroscopy. This Specialist Periodical Report on Photochemistry aims to provide an annual review of photo-induced processes that have relevance to the above wide-ranging academic and commercial disciplines, and interests in chemistry, physics, biology and technology. In order to provide easy access to this vast and varied literature, each volume of Photochemistry comprises sections concerned with photophysical processes in condensed phases, organic aspects which are sub-divided by chromophore type, polymer photochemistry, and photochemical aspects of solar energy conversion. Volume 34 covers literature published from July 2001 to June 2002. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.

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Photochemistry Volume 2

A Review of the Literature Published between July 1969 and June 1970

By D. Bryce-Smith

The Royal Society of Chemistry

Copyright © 1971 The Chemical Society
All rights reserved.

ISBN: 978-0-85186-015-2

Contents

Introduction and Review of the Year By D. Bryce-Smith, xi, 
Part I Physical Aspects of Photochemistry, 
Chapter 1 Spectroscopic and Theoretical Aspects By D. Phillips, 
Chapter 2 Photophysical Processes in Condensed Phases By D. Phillips, 
Chapter 3 Gas-phase Photochemistry By D. Phillips, 
Part II Inorganic Photochemistry By D. Phillips, 
1 Photochemistry of Water, H2O2,and Aqueous Anions, 235, 
2 Photochemistry and Photoluminescence of Transition-metal Co-ordination Complexes, 243, 
3 Gas-phase Studies, 281, 
4 Solid-phase Luminescence and Photoreactions, 287, 
Part III Organic A spects of Photochemistry, 
Chapter 1 Photolysis of Carbonyl Compounds By W. M. Horspool, 
Chapter 2 Enone Rearrangements and Cycloadditions: Photoreactions of Cyclohexadienones, Tropones, Quinones, etc. By W. M. Horspool, 
Chapter 3 Photochemistry of Ole(lns, Acetylenes, and Related Compounds By W. M. Horspool, 
Chapter 4 Photochemistry of Aromatic Compounds By A. Gilbert, 
Chapter 5 Photo-oxidation and -reduction Reactions By A. Gilbert, 
Chapter 6 Photoreaclions of Compounds Containing Heteroatoms other than Oxygen By A. Gilbert, 
Chapter 7 Photoelimination Reactions By A. Gilbert, 
Part IV Polymer Photochemistry By D. Phillips, 
1 Photopolymerization, 757, 
2 Optical Properties of Photoexcited Polymers, 770, 
3 Photo-cross-linking and Grafting, 776, 
4 Photodegradation and Stabilization, 
Errata, 800, 
Author Index, 801, 

CHAPTER 1

Part I

PHYSICAL ASPECTS OF PHOTOCHEMISTRY

1

Spectroscopic and Theoretical Aspects

As was stated in Volume 1 of this series, the experimental photochemist can learn much from a study of the absorption spectroscopy of molecules under his investigation. Thus, details of the nature of the excited states formed upon absorption, radiative lifetimes of these states, changes in dipole moment and polarizability (and consequently reactivity) may be obtained from a careful study of the electronic absorption spectra. Frequently information obtained in this way is augmented by ab initio, or more usually semi-empirical, calculations upon the energy levels and properties of excited states of molecules. Together, theoretical and spectroscopic considerations can often provide a rationale for the photochemists' experimental observations. The volume of material of a spectroscopic and theoretical nature published annually is vast, however, and it would be impossible, and indeed misplaced, to attempt to include a comprehensive survey of this field in this volume. Instead a brief section is included on absorption spectra and energy level calculations which may be of direct interest to the photochemists for whom this volume is intended. References to other theoretical and spectroscopic work will often be found in sections dealing with the photochemistry of specific molecules.

As in Volume 1, a considerable section of this chapter will be devoted to theoretical considerations of radiationless transitions. This is an area in which experimental evidence is building up, and the phenomenon provides a challenge to theoreticians and experimentalists alike to gain a deeper understanding of the complex nature of these processes. It must be stressed that the authors of this volume are primarily experimentalists, and the account given here of the efforts of colleagues engaged upon the difficult task of providing an adequate theory which will quantitatively account for observed rates of internal conversions and intersystem crossings may be coloured by a lack of understanding of the true complexities of the problem.

The extensive data which are available on the rates of decomposition of molecules in the gas phase have been treated in the past in only a semi-quantitative manner, but it is encouraging to note that there has been an increasing tendency of late to apply the theories of unimolecular decomposition to excited states of molecules. A short section is devoted to this and other theoretical aspects of photodecomposition, and some further applications of the Rice–Rampsberger–Kassel–Marcus (RRKM) treatment to excited states of molecules in the gas phase will be found in Chapter 3.

Finally, we have included a section on developments of new experimental techniques in this Chapter. This section belongs properly with the experimental sections Chapters 2 and 3, but since the techniques described are principally of a spectroscopic nature, and often apply equally to condensed phase and gas-phase investigations, the section will be included here as a preface to both Chapter 2 and Chapter 3.

1 Absorption Spectra and Energy Level Calculations

As stated above, this section is not intended to be comprehensive, but a selection of published papers on molecules which may be of interest to photochemists is given. These molecules will be dealt with in order of increasing complexity. The calculation of Franck-Condon factors is of importance in that these determine the intensities of both radiative and non-radiative transitions. In small molecules, work has continued on investigations into hitherto neglected vibration-rotation interactions in the calculation of Franck-Condon factors. For the hydrogen molecule, the (B1Σu+<- X1Σg+), (I1Πg<- B1Σu+), (d3Πu<- a3Σg+), (C1Πu<- X1Σg+), (D1Πu<- X1Σg+), (h3Σu+<- c3Πu) systems, the E1Σg+<- B1Σu+), (G1Σg+<- B1Σu+), and (kΠu<- a3Σg+) systems, have been extensively studied. In all cases good agreement with experiment is possible if vibration–rotation interactions are considered. Previous computations, for e.g. the Lyman bands, have not included the effects of the centrifugal potential, but it has been tacitly assumed that the principal effect of the rotational energy is a shift of the potential curve by a constant energy displacement. This assumption is most severely tested in calculations of Franck–Condon factors for electronic transitions in light molecules, and especially if the transition involves states with appreciably different potential curves, as in the (BΣu+<- XΣg+) Lyman system. The rotational angular momentum necessarily changes in all transitions (since there is no Q branch, it being a Σ <- Σ transition), and this serves to emphasize the vibration–rotation interaction effects. By way of contrast, the (d3Πu<- a3Σg+) Fulcher bands arise from states which have similar potential curves, and smaller vibration-rotation interaction effects on intensities would be anticipated.

When the centrifugal potential is explicitly taken into account, the Franck–Condon factor appropriate to the electronic transition (v', J' ->v", J")] is given by:

q(v', J'; v", J") = | [∫ φ'v', J' (R) φ"v", J"(R) d R|2 (1)

where φv', J'(R) and φv", J"(R) are the eigenfunctions of the nuclear motion...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 1971
• Sprache: Englisch
• ISBN 10: 085186015X
• ISBN 13: 9780851860152
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 836
• Herausgeber: Bryce-Smith D.
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: GPSR Kontakt; gpsr@libri.de; ; Europaallee 1; Bad Hersfeld; 36244; Deutschland