1,721,022 research outputs found
Electron nuclear double resonance of the first excited triplet state of trans-stilbene in a diphenylacetylene-TCNB single crystal.
No full textThe first excited triplet state of trans-stilbene, contained as an impurity in diphenylacetylene-TCNB single crystal has been investigated by ENDOR spectroscopy. The hyperfine tensors of six pairs of equivalent protons of trans-stilbene have been measured. They show that in this host crystal the trans-stilbene has a centre of symmetry. The isotropic couplings compare well with those of the trans-stilbene radical anion. The calculated dipolar tensors agree with the experimental ones if the trans-stilbene molecule is assumed as planar and the in-plane principal direction x of the zero-field splitting tensor makes an angle of 12° with the central double bond. With such orientation the trans-stilbene is found to substitute one diphenylacetylene molecule with minimum distortion of the crystal lattice
ESR Investigation of Mn Carbonyl Complexes Formed by Reaction of Mn2(CO)10 with Electron Acceptor Molecules.
No full textENDOR 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
ENDOR spectra of pyrene excited triplet state in naphtalene-TCNB crystals
No full textTriplet state traps, observed on optically excited single crystals of Naphthalene-TCNB doped with Pyrene, have
been studied by EPR and ENDOR spectroscopy. The magnetic resonance lines recorded at low temperature (20K) are
shown to be due to triplet excitations localized almost completely on a Pyrene molecule. The complete hyperfine tensors
of all the protons have been determined. The spin distribution is shown to be distorted in such a way that the triplet
Pyrene molecule lacks the in-plane symmetry axes of the ground state molecule. The orientation of the triplet molecule in
the crystal lattice and the relative orientation of Pyrene and TCNB are also discussed
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
Theoretical study of the beta-protons hyperfine splitting parameter of hydrocarbon radicals
No full textElectron nuclear double resonance of S=1/2 defects in a single crystal of the morpholinium-TCNQ 1:1 complex.
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