1,721,003 research outputs found
Proton ENDOR spectra of phenanthrene-TCNB triplet traps in single crystals of naphthalene-TCNB.
No full textThe ENDOR spectra of triplet traps of phenanthrene-TCNB in doped single crystals of naphthalene-TCNB have been recorded and the complete hyperfine tensors of all the protons have been measured. The spin densities on the carbon atoms are obtained from the isotropic as well as from the anisotropic part of the tensors. The spin density distribution on phenanthrene inphenanthrene-TCNB differs from that of the pure phenanthrene in its first excited triplet state, due to a polarizing effect of the acceptor. The CT degree is obtained from the reduction of the total spin density on the donor molecule and it results to be 40%. The structure of the trap is also discussed
Simulation of EPR and Time Resolved EPR lineshapes in partially ordered phases
No full textSimulation of magnetic resonance spectra of probes in partially ordered glasses requires in principle a numerical integration on the full set of three Euler angles Ohm=(alpha beta gamma) from a laboratory fixed to a molecule fixed reference frame. It is shown that it is possible to manage efficiently this problem by using the algebraic properties of the Wigner matrix elements. This analysis is applied to time resolved EPR (TREPR) spectra of a series of bis-adducts of C-60 in the ordered glass of a nematic liquid crystal solvent. A paramagnetic triplet state is created by light excitation and TREPR spectra are obtained with the external magnetic field set parallel or perpendicular to the director n of the mesophase. The preferred orientation in the mesophase of the triplet state zero field tensor is determined
ENDOR of the pyrene triplet-state in the charge-transfer crystal naphthalene tetracyanobenzene.
No full textENDOR measurements of the pyrene-TCNB excited triplet state in the CT crystal of naphthalene-TCNB have been performed at 130 K. Proton hyperfine tensors of both the donor and the acceptor molecule have been determined. Isotropic hyperfine coupling constants have served to obtain spin distribution and CT character (16%) of the trap. Experimental hyperfine dipolar tensors of pyrene protons are averaged by motion and are reproduced by a dynamical model in which rotation of ± 16° about the long in-plane axis accompanied with that of ± 5° about the normal to the molecular plane. © 1985
ESR Investigation of Mn Carbonyl Complexes Formed by Reaction of Mn2(CO)10 with Electron Acceptor Molecules.
No full text
EPR study of in-plane anisotropy in the LB films of a Cu(II)[tetraalkoxycarbonyl] phthalocyanine deposited on mylar sheets
No full textIntermolecular electron transfer in merocyanine aggregates studied by optical and transient EPR methods
No full textExcited states of two merocyanine chromophores have been studied by means of optical and magnetic resonance techniques. The dye molecules were dissolved in solvents of different polarity and cast in thin films on quartz surfaces. The optical absorption and emission spectra of both molecules indicate a little charge-transfer character in the S-0-S-1 transition. The cast films contain monomers and H type aggregates. EPR spectra have been obtained by time resolved techniques at low temperature after illumination of the sample. EPR spectra of isolated molecules in frozen solutions are typical of triplet excited states generated by spin-orbit promoted intersystem crossing. Two signals are observed in EPR spectra of the cast films, with a narrow line in emission superimposed on a very weak molecular triplet lineshape. The polarization and lineshape analysis suggest that a radical ion pair with a lifetime of the order of microseconds is formed by intermolecular charge migration following the photoinduced electron-transfer reaction between the donor and acceptor moieties of the chromophore
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