Photochemistry: Volume 27 (Specialist Periodical Reports, Band 27) - Hardcover

Hardcover

ISBN 10: 0854044051 ISBN 13: 9780854044054

Verlag: Royal Society of Chemistry, 1996

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 27

A Review of the Literature Published Between July 1994 and June 1995

By A. Gilbert

The Royal Society of Chemistry

Copyright © 1996 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-0-85404-405-4

Contents

Introduction and Review of the Year By Andrew Gilbert, 1, 
Part I Physical Aspects of Photochemistry, 
Photophysical Processes in Condensed Phases By Robert B. Cundall, 15, 
Part II Organic Aspects of Photochemistry, 
Chapter 1 Photolysis of Carbonyl Compounds By William M. Horspoo, 63, 
Chapter 2 Enone Cycloadditions and Rearrangements; Photoreactions of Dienones and Quinones By William M. Horspool, 80, 
Chapter 3 Photochemistry of Alkenes, Alkynes, and Related Compounds By William M. Horspool, 129, 
Chapter 4 Photo-reduction and -oxidation By Alan Cox, 161, 
Chapter 5 Photoreactions of Compounds containing Heteroatoms other than Oxygen By Stewart T. Reid and Andrew Gilbert, 216, 
Chapter 6 Photoelimination By Stewart T. Reid and William M. Horspool, 262, 
Part III Polymer Photochemistry By Norman S. Allen, 303, 
Part IV Photochemical Aspects of Solar Energy Conversion By Alan Cox, 363, 
Author Index, 371, 

CHAPTER 1

Part I

Physical Aspects of Photochemistry

By Robert B. Cundall

Photophysical Processes in Condensed Phases

BY R.B. CUNDALL

1 Introduction

Research in condensed phase photophysics continues to be actively concerned with the elucidation of the details of the elementary processes capable of study by ultrafast time resolution techniques. Charge transfer effects are again of major interest and, in particular the diversity of photochemical processes involving the fullerenes continues to widen further.

2 General

The timely appearance of a volume dealing with ultrafast processes in chemistry and photobiology in a series dealing with "Chemistry for the 21st Century" is an authoritative survey for all photochemists. Other reviews of this area include one on femtochemistry by Thorne and Beddard and another on vibrational relaxation dynamics in solution. The latter is concerned mainly with smaller molecules but there is an analysis of effects in proteins and surface adsorbates. Many aspects of photophysics are covered in papers presented at a discussion meeting on molecular spectroscopy and molecular dynamics held in 1994. The January issue of Applied Spectroscopy in 1995 contains twelve papers dealing with several aspects of molecular fluorescence.

Reviews on the photophysical and photochemical properties of the fullerenes and excited states and electron transfer reactions of fullerenes, and several papers published from the proceedings of a symposium on fullerenes give a perspective of progress in this topical area.

A number of papers with a theoretical emphasis deal with the details of ultrafast processes. Wynne and Hochstrasser develop the theory of ultrafast vibrational spectroscopy and in particular analyse the effect of vibrational modes which couple to bring about photochemically induced reactions: a subject of considerable interest. A closely related experimental study has been reported on energy flow from excited solute molecules to the solvent probed by fs IR spectroscopy for the specific cases of malachite green and haem protein solutions where the response times are a few ps. Fleming and his coworkers have used fs wavepacket spectroscopy to examine the influence of temperature, wavelength, and pulse duration. The pulses used in this work are effectively shorter in duration than the vibrational period of the excited molecules. Electronic coherence in pseudo two colour pump probe spectroscopy provides a method for extracting information on electronic coherence dynamics. This technique is particularly useful in situations where there are overlapping bands. The dynamics of chemical processes in polar solvents and the solvation dynamics and dielectric response in the glass forming solvent, 2-methyltetrahydrofuran, occurring over time ranges from ps to seconds are reports on systems of wide interest. The polarity response of pyrene fluorescence through vibronic coupling is well known and the effect has been analysed in detail by Karpovich and Blanchard. Although the treatment presented involves diatomic molecules the Brownian oscillator model for solvation effects in light emission and its relationship to electron transfer processes is a useful contribution to knowledge of primary processes. A good correlation between solvatochromic Stokes shift data and values of excited state dipole moments has also been achieved. Ultrafast time resolved spontaneous and coherent Raman spectroscopy are techniques for studying the structure and dynamics of photogenerated transients which have been reviewed. Attention is given in this paper to ring opening in paraphenylene, photobiologically related polyenes, and the photophysical properties of stilbene and related compounds. A technique for the direct detection of zwitter-ionic excited states has also been described.

The fluorescence spectra and values of the integrated emission have been used to study preferential solvation in supercritical fluid mixtures. Pyrene has been used to estimate the degrees of selective solvation which occur in CO2/CHFz3 supercritical mixtures. Molecular effects in organic solvents are important in affecting excimer fluorescence as shown by hydrogen bond interaction effects examined by NMR. Unusual environmental effects have been studied in observations made on the excited state solvation dynamics of tetraalkylammonium salts in the solid and molten states. Solvation processes are the same in both situations but are slower in the solid. Another paper deals with the effect of intermolecular vibronic coupling on nonradiative transitions and the optical absorption of dimers.

A theoretical analysis carried further by Molski develops relations among steady state, time and frequency domain fluorescence quenching rates using a statistical approach based on the principles of non-equilibrium thermodynamics. A distinction between differing competing kinetic models of irreversible two-state excited state processes with a quencher can be made by global analysis of the fluorescence decay surface. A theoretical analysis has been made of fluorescence and absorption in molecular complexes with two chromophores and non-parallel absorption and emission transition dipole moments. Time dependence of optical polarization is re-examined with regard to the predictions of the established Perrin model. The effects of light intensity on diffusion influenced fluorescence quenching have been examined for the case of a model using a hard sphere liquid. Diffusional limitations and consequent effects in liquid phase photocatalysis are extensively surveyed.

Nonlinearity effects can arise from the strong interaction of vibrations and thermal fluctuations and induce a development of limit cycles in fluorescence depolarization.

Other papers dealing with time resolved fluorescence studies include a theoretical examination of fluorescence anisotropy arising from a coupled chromophore pair where there is an influence of nuclear motion and energy transfer, the effect of added quencher on bichromophoric emission, the analysis of intermolecular two state excited state processes, a new method for the analysis of multi-component exponential decays, and the analysis of anisotropy decays in terms of the correlation time distributions measured by frequency domain spectroscopy. Multidimensional least...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 1996
• Sprache: Englisch
• ISBN 10: 0854044051
• ISBN 13: 9780854044054
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 416
• Herausgeber: Gilbert A.
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: gpsr@libri.de; gpsr@libri.de; ; Friedensallee 273; Hamburg; 22763; Deutschland