16,313 research outputs found
Magnetic properties of the doped two-dimensional antiferromagnet
The variety of the normal-state magnetic properties of cuprate high-Tc
superconductors is interpreted based on the self-consistent solution of the
self-energy equations for the two-dimensional t-J model. The observed
variations of the spin correlation length with the hole concentration x, of the
spin susceptibility with x and temperature T and the scaling of the static
uniform susceptibility are well reproduced by the calculated results. The
nonmonotonic temperature dependence of the Cu spin-lattice relaxation rate is
connected with two competing tendencies in the low-frequency susceptibility:
its temperature decrease due to the increasing spin gap and the growth of the
susceptibility in this frequency region with the temperature broadening of the
maximum in the susceptibility.Comment: 6 pages, 5 figures, Proc. Int. Conf. "Modern Problems of
Superconductivity", 9-14 Sept. 2002, Yalta, Ukrain
Electron Transfer in Porphyrin Complexes in Different Solvents
The electron transfer in different solvents is investigated for systems
consisting of donor, bridge and acceptor. It is assumed that vibrational
relaxation is much faster than the electron transfer. Electron transfer rates
and final populations of the acceptor state are calculated numerically and in
an approximate fashion analytically. In wide parameter regimes these solutions
are in very good agreement. The theory is applied to the electron transfer in
with free-base porphyrin () being the donor,
zinc porphyrin () the bridge, and quinone () the acceptor.
It is shown that the electron transfer rates can be controlled efficiently by
changing the energy of the bridging level which can be done by changing the
solvent. The effect of the solvent is determined for different models.Comment: 28 pages + 5 figures, submitted to J. Phys. Chem. For more details
see the Ph. D. thesis in quant-ph archive
http://xxx.lanl.gov/abs/quant-ph/000100
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