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Library Catalogue

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    Union Catalogue of Agricultural Libraries in the Netherlands

    The WUR Library Catalogue contains bibliographic data on books and periodicals held by the libraries of Wageningen University and Research Centre and some 15 associated libraries. Holding data are added to each record.

    Subjects covered include Agrotechnology, Food and Food Production, Plant and Animal Sciences, Soil Science, Geo-information, Landscape and Spatial Planning, Water and Climate, Ecosystem Studies, Economics and Society.

    The joint collections of the participating libraries cover a substantial part of the internationally available scientific literature in these disciplines.

    As far as Dutch scientific literature in these fields is concerned, coverage can be considered near 100%, including much of the so-called "grey literature".

    All titles are entered in their original language. Keywords are added to facilitate subject searching.

    The database is updated every day and now contains over 830.000 records.

Record number 104048
Title The interaction of light and microwaves with photosynthetic pigments
show extra info.
S.J. van der Bent
Author(s) Bent, S.J. van der
Publisher [S.l. : s.n.]
Publication year 1977
Description 117 p
Notes Proefschrift Wageningen
Tutors Schaafsma, Prof. Dr. T.J.
Graduation date 1977-12-08
Dissertation no. 703
Author abstract show abstract
In this Thesis the results of investigations on the lowest excited triplet state of photosynthetic pigments and some model compounds are presented, partly as reprints of published papers. Most of the experiments are carried out using ODMR ( O ptically D etected of M agnetic R esonance), detecting microwave-induced changes in the populations of the spin states of the lowest excited triplet state, via induced changes in the fluorescence emission.

10 -6-10 -7M chlorin free base incorporated as a guest in a n-octane single crystal proved to be a very attractive model for the study of the zero-field-splittings and the decay rate constants of the lowest excited triplet state. Contrary to naturally occurring compounds such as pheophytins and chlorophylls, chlorin can be easily studied without effects of polar solvents and aggregation.. Since chlorin has the same conjugation pathway as the chromophoric group of chlorophyll-a and b and the corresponding pheophy tins, it is interesting to determine its properties. As already has been found for porphin free base by other groups, chlorin exhibits photoinduced rotation of the two central protons at 4.2 K, but at a much slower rate than porphin. In vitro studies of pheophytins-a and -b have learned that the ODMR technique can be fruitfull in unraveling optical emission spectra of systems containing molecules in different solvated states, which have overlapping optical absorption and emission bands. The results suggest a correlation between the red shift of the fluorescence emission and the spin-lattice-relaxation-rate of molecules in polar environ ments. A exploratory study has been made of the application of the ODMR technique to in vivo photosynthetic systems such as intact algae. Although hindered by spin-lattice-relaxation at 4.2 K causing a poor signal-to-noise ratio. the technique is promising for the study of whole algae. Since in biological systems both spin-lattice-relaxation and triplet-triplet absorption may cause difficulties in determining the kinetic constants of the lowest excited triplet state, a detailed computer analysis is made of the possible influence of these effects on the measured decay rate constants and populating rates. This analysis indicates the importance of including higher excited singlet and triplet states into the optical pumping cycle for the understanding of ODMR results.

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On paper FORUM ; STACKS ; NN08200,703
FORUM ; STACKS ; NN08202,703
Keyword(s) (cab) photosynthesis / synthesis / photochemistry
Categories Photochemistry and Photophysics
Publication type PhD thesis
Language English
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