7,851 research outputs found
Long-range repulsive interaction between TTF molecules on a metal surface induced by charge transfer
The low-coverage adsorption of a molecular electron donor,
tetrathiafulvalene, on Au(111) is characterized by the spontaneous formation of
superlattice of monomers, whose spacing exceeds the equilibrium distance of
non-covalent interactions and depends on coverage. The origin of this peculiar
growth mode is due to a long-range repulsive interaction between molecules. The
analysis of molecular-pair distributions obtained by scanning tunneling
microscopy measurements permits us to determine that the nature of TTF
intermolecular interactions on Au (111) is electrostatic. A repulsion between
molecules is caused by the accumulation of charge due to electron donation into
the metal surface, as pictured through density functional theory calculations
Recombination limited energy relaxation in a BCS superconductor
We study quasiparticle energy relaxation at sub-kelvin temperatures by
injecting hot electrons into an aluminium island and measuring the energy flux
from electrons into phonons both in the superconducting and in the normal
state. The data show strong reduction of the flux at low temperatures in the
superconducting state, in qualitative agreement with the presented
quasiclassical theory for clean superconductors. Quantitatively, the energy
flux exceeds that from the theory both in the superconducting and in the normal
state, possibly suggesting an enhanced or additional relaxation process
TELEPENSOUTH project: Measurement of the Earth gravitomagnetic field in a terrestrial laboratory
We will expose a preliminary study on the feasibility of an experiment
leading to a direct measurement of the gravitomagnetic field generated by the
rotational motion of the Earth. This measurement would be achieved by means of
an appropriate coupling of a TELEscope and a Foucault PENdulum in a laboratory
on ground, preferably at the SOUTH pole. An experiment of this kind was firstly
proposed by Braginski, Polnarev and Thorne, 18 years ago, but it was never
re-analyzed.Comment: 7 pages, LaTeX, Springer style files included. Contribution to the
Proceedings of the Spanish Relativity Meeting-ERE-2001 (Madrid, September
2001). To appear in the book "Relativistic Astrophysics", Lecture Notes in
Physics, Springer Verlag (2002), edited by L. Fernandez-Jambrina, L.M.
Gonzalez-Romer
Tunable crystal structure and proton conductivity of lanthanide nitrilotrismethylphosphonates
Metal phosphonates are multifunctional solids with remarkable stability and proton conducting properties owing
to their structure is usually composed of extended hydrogen-bond networks that favor proton transfer pathways [1].
Moreover, these properties can be enhanced by appropriate modification of the synthesis conditions [2, 3].
In this communication, a new family of isostructural 2D layered compounds based on lanthanide nitrilotris-methylphosphonates
is reported. These compounds have been isolated at room temperature and have the general formula Ln[N(CH2)3(PO3H2)2(PO3H)(H2O)]SO4·2H2O (Ln= Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb). The coordination environment
of Ln3+ is composed by eight oxygen atoms from three different ligands and two oxygens from bound waters.
This connectivity creates positive charged layers connected to sulfate ions through hydrogen-bonds. These compounds
show promising proton conductivity with values ranging between 7.6·10-2 and 3.8·10-2 S·cm-1 at 80 °C and 95% RH
and low activation energy corresponding to Grotthuss-type proton transfer mechanism. In addition, a structural transformation
occurs at T > 70 °C accompanied by a remarkable enhanced conductivity. Studies on the structure-properties relationships will be discussed.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech.
MINECO: MAT2016-77648-R
Junta AndalucĂa: P12-FQM-1656 y FQM-11
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