✦ LIBER ✦

EPR study of electron spin polarization in the photoexcited triplet state of chlorophyll a and b

✍ Scribed by Haim Levanon; Avigdor Scherz

Publisher: Elsevier Science
Year: 1975
Tongue: English
Weight: 556 KB
Volume: 31
Category: Article
ISSN: 0009-2614
DOI: 10.1016/0009-2614(75)80073-x

No coin nor oath required. For personal study only.

✦ Synopsis

The photoexcitcd triplet states of chlorophyll a and b are studied by the EPR method at -85 K using modulated ii&t excitation. Both compounds show anomalous EPR line intensities and transient kinetics, indicating e!ectron spin polxi~ation (ESP) in the photoexcitcd triplet state. EPR studies, using hlg-tetraphenyl porphyrin (MgTPPj dissolved in rr-octane show that ESP occurs also in thnt solvent. It is shown that the zero field splitting (ZFS) parameters of MgTPP depend strongly on the solvent. From the analysis of the data for chlorophyll r~ nnd b we evaluate: (1) the population rate constants -($J; (2) the ratio between the population rate constantslAp) (p = X, y, z) and, (3) the spin lattice relaxation rate IV. In both chlorophyl!s the in-plane component, X. is predominantly populated znd depopulated. The ZFS par;?meters hzve been also determined for the nbovc compounds.

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