138 research outputs found
Oxo-centered carboxylate-bridged trinuclear complexes deposited on Au(111) by a mass-selective electrospray.
We developed an apparatus for nondestructive in vacuum deposition of mass-selected fragile Cr based metal trinuclear complexes, by modifying a commercial Mass Spectrometer containing an electrospray ionization source. Starting from a solution, this system creates a beam of ionized molecules which is then transferred into an evacuated region where the molecules can be mass selected before deposition. To verify the system efficiency, we deposited sub monolayers of oxo-centered carboxylate-bridged trinuclear complexes (Cr3 and Cr2Ni) on Au(111) surface. By XPS and STM we determined the deposited molecule stoichiometry and the surface coverage. The results show that this apparatus is works well for the in vacuum deposition of molecular nanomagnets and, thanks to its reduced dimensions, it is portable
Fabrication of three terminal devices by ElectroSpray deposition of graphene nanoribbons
Electrospray deposition (ESD) in ambient conditions has been used to deposit graphene nanoribbons (GNRs) dispersed in liquid phase on different types of substrates, including ones suitable for electrical transport. The deposition process was controlled and optimized by using Raman spectroscopy, Scanning Probe Microscopies and Scanning Electron Microscopy. When deposited on graphitic electrodes, GNRs were used as semi-conducting channel in three terminal devices showing gate tunability of the electrical current. These results suggest that ESD technique can be used as an effective tool to deposit chemically synthesized GNRs onto substrates of interest for technological applications
Magnetic interplay between two different lanthanides in a tris-phthalocyaninato complex: a viable synthetic route and detailed investigation in the bulk and on the surface
Future applications of molecular units in quantum information technologies require a fine control at the
single molecule level. This includes the choice of each functional element, the intramolecular interaction
and the robustness of molecules when dispersed on a substrate. Keeping these goals in mind, we
designed and synthesized a heterometallic phthalocyaninato-complex including two different lanthanides
in each moiety, namely [PcDyPcTbPc*] (Pc being phthalocyanines; and Pc* being 2,3,9,10,16,17,23,24-
octahexyl-substituted phthalocyanines). Full magnetic characterization was performed down to the mK
temperature range on bulk microcrystals by means of AC susceptibility, DC magnetization (including
microSQUID) and specific heat measurements. A weak, yet sizeable, interaction between the two
lanthanides is clearly detected by different techniques, altering the magnetic behavior of the single
lanthanide as observed in the parent [LnPc2] complexes. Isolated [PcDyPcTbPc*] molecules dispersed on
HOPG and the Au surface by liquid phase deposition are proven to maintain their main chemical and
magnetic features by combined XPS, XAS and XMCD analysis and to lie with one Pc ligand flat to the
surface. Opening of a small but sizable hysteresis loop at 1.8 K is directly observed on both Tb and Dy
sites proving the retention of magnetization at the single molecule level
Antiferromagnetic coupling of TbPc2 molecules to ultrathin Ni and Co films
The magnetic and electronic properties of single-molecule magnets are studied by X-ray absorption spectroscopy and X-ray
magnetic circular dichroism. We study the magnetic coupling of ultrathin Co and Ni films that are epitaxially grown onto a Cu(100)
substrate, to an in situ deposited submonolayer of TbPc2
molecules. Because of the element specificity of the X-ray absorption
spectroscopy we are able to individually determine the field dependence of the magnetization of the Tb ions and the Ni or Co film.
On both substrates the TbPc2 moleculescouple antiferromagnetically to the ferromagnetic films, which is possibly due to a superexchange interaction via the phthalocyanine ligand that contacts the magnetic surface
Spin-communication channels between Ln(III) bis-phthalocyanines molecular nanomagnets and a magnetic substrate
Learning the art of exploiting the interplay between different units at the atomic scale is a fundamental step in the realization of functional nano-architectures and interfaces. In this context, understanding and controlling the magnetic coupling between molecular centers and their environment is still a challenging task. Here we present a combined experimental-theoretical work on the prototypical case of the bis(phthalocyaninato)-lanthanide(III) (LnPc 2) molecular nanomagnets magnetically coupled to a Ni substrate. By means of X-ray magnetic circular dichroism we show how the coupling strength can be tuned by changing the Ln ion. The microscopic parameters of the system are determined by ab-initio calculations and then used in a spin Hamiltonian approach to interpret the experimental data. By this combined approach we identify the features of the spin communication channel: the spin path is first realized by the mediation of the external (5d) electrons of the Ln ion, keeping the characteristic features of the inner 4 f orbitals unaffected, then through the organic ligand, acting as a bridge to the external world
Edge Dislocation Behaviour in Au-n Silicon Diodes
By measuring the reverse bias chararcteristics of Au-nSi diodes made from deformed silicon, with variable content of edge dislocations, their electronic properties are deduce
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