Time-resolved electron paramagnetic resonance spectroscopy

In a supramolecular approach to fullerene-porphyrin hybrids, the assembly of a rigidly connected dyad, in which a zinc tetraphenylporphyrin, Zn(TPP), is noncovalently linked to a C60 derivative via axial pyridine coordination to the metal, was reported [219-222]. Photo excitation of the dyad Zn-complex led to electron transfer with very long lifetimes of the charge-separated pairs, as revealed by optical spectroscopy and confirmed by time-resolved electron paramagnetic resonance spectroscopy. Accordingly, two different solvent-dependent pathways can be considered for the electron-transfer processes. Either the excitation of the porphyrin chromophore is followed by fast intramolecular electron transfer inside the complex, or alternatively the free porphyrin is excited undergoing intermolecular electron transfer when the acceptor molecules ap-... [Pg.20]

TA-transient absorption TRANIP = time-resolved anisotropy TRPL = time-resolved photoluminescence TRIR = time-resolved IR TR = EPR-time-resolved electron paramagnetic resonance spectroscopy. [Pg.2767]

In all covalent electron donor-acceptor systems produced earlier, triplet states observed by EPR were formed via a spin-orbit intersystem crossing (SO-ISC) mechanism. Another possible mechanism of triplet formation is RP-ISC, mentioned above, which results from radical ion pair recombination, and which had been observed previously by time-resolved electron paramagnetic resonance spectroscopy (TREPR) only in bacterial reaction centers and in the green plant Photosystem I and II reaction centers. These two mechanisms can be differentiated by the polarization pattern of the six EPR transitions at the canonical orientations. In SO-ISC,... [Pg.3242]

Bordignon E, Klare JP, Holterhues J, Martell S, Krasnaberski A, Engelhard M, Steinhoff HJ (2007) Analysis of light-induced conformational changes of Natronomonas pharaonis sensory rhodopsin II by time resolved electron paramagnetic resonance spectroscopy. Photochem Photobiol 83(2) 263-272... [Pg.154]

Time-resolved electron paramagnetic resonance spectroscopy history, technique, and application to supramolecular and macromolecular chemistry, 47, 1... [Pg.298]

R 87 T. Yamase, Time-Resolved Electron Spin Resonance Spectroscopy of Photoredox Reactions of Polyoxometalates Formation of Paramagnetic-Species Pair by Triplet Mechanism , p. 211 Vol. 102,2003... [Pg.8]

KE Dukes, EJ Harbron, MDE Forbes. Flow system and 9.5 Ghz microwave resonators for time-resolved and steady-state electron paramagnetic resonance spectroscopy in compressed and supercritical fluids. Rev Sci Instrum 68 2505, 1997. [Pg.60]

We have used two spectroscopic methods to investigate the triplet state of localized diradicals. On the one hand, matrix electron paramagnetic resonance (EPR) spectroscopy was employed, which affords the zero-field splitting (zfs) parameters D and E and gives valuable information on the electronic structure [5-7]. On the other hand, time-resolved transient... [Pg.207]