Interaction of chlorophyll with light : calculations of absorption spectra and dichroism with a new technique /
The response of a single chlorophyll molecule to light was studied using a semiemirical tight-binding model together with the Peierls substitution. Over a range of wavelengths, the absorption was calculated for unpolarized, linearly polarized, and circularly polarized light. The results are consiste...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733677931&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The response of a single chlorophyll molecule to light was studied using a semiemirical tight-binding model together with the Peierls substitution. Over a range of wavelengths, the absorption was calculated for unpolarized, linearly polarized, and circularly polarized light. The results are consistent with previous experiments, although detailed comparisons are not possible because the experiments involve chlorophyll molecules in more complicated environments. For unpolarized light, the absorption peaks in the red part of the visible spectrum. There is a secondary shoulder in the blue. For linearly polarized light, the absorption depends on wavelength and the direction of polarization. This can be understood as arising from the joint density of states for transitions at each photon energy, together with matrix-element effects (both of which are included in the present formulation). For circular polarization, the dichroism as a function of wavelength is slightly more subtle, but again can be understood in terms of matrix elements for the states involved in a transition at a given photon energy. We also found that an "effective helicity'' is useful in understanding the circular dichroism. One advantage of the method used here is that it can be employed for other molecules that are important in protobiology - for example, retinal and melanin. |
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| Item Description: | Vita. "Major Subject: Physics". |
| Physical Description: | xiii, 146 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 106-110). |