B896 and B870 components of the Rhodobacter sphaeroides antenna: a hole burning study
| Autor: | Rafael Picorel, N. R. S. Reddy, Gerald J. Small |
|---|---|
| Přispěvatelé: | Picorel Castaño, Rafael, Picorel Castaño, Rafael [0000-0003-3791-129X] |
| Jazyk: | angličtina |
| Rok vydání: | 1992 |
| Předmět: |
TRANSFER DYNAMICS
Absorption spectroscopy Scattering Chemistry Dephasing Exciton General Engineering BACTERIOCHLOROPHYLL-A PROSTHECOCHLORIS-AESTUARII Coupling (probability) Spectral line ELECTRON-DONOR STATE chemistry.chemical_compound RHODOPSEUDOMONAS-SPHAEROIDES PIGMENT-PROTEIN COMPLEX LOW-TEMPERATURE ABSORPTION PHOTOSYNTHETIC BACTERIA EXCITATION-ENERGY TRANSFER PURPLE PHOTOSYNTHETIC BACTERIA Bacteriochlorophyll Physical and Theoretical Chemistry Atomic physics Absorption (electromagnetic radiation) |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | 7 Pags. Novel nonphotochemical hole burning action spectra are persented that yield the low-temperature absorption profiles of B896 and B870 and their underlying structures (linear electron-phonon coupling and site inhomogeneous broadening). The results establish that B896 and B870 are associated with the far more intense B875 and B850 bacteriochlorophyll a absorption bands, respectively, of the light harvesting I and II complexes. The homogeneous widths of the B896 and B870 zero-phonon holes are the same within experimental uncertainty, 3.2 cm-1 at 4.2 K, which corresponds to a total optical dephasing time of 6.6 ps. A number of interpretations for B870 and B896 are considered. Favored is one in which they are due to the lowest energy levels of the B850* and B875* exciton bands (asterisk denoting the S1(Q(y)) state). Based on studies of the dephasing of excitons in organic crystals, the 6.6-ps dephasing of B896* is attributed to exciton scattering with energetic inequivalent neighboring unit cells. Such scattering and B870 to B875 energy transfer are suggested to be contributors to the dephasing of B870*. The effect of glasslike structural heterogeneity on the optical selection rules for unit cells of cyclic symmetry is also considered. |
| Databáze: | OpenAIRE |
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