Vacuum synthesis of magnetic aluminum phthalocyanine on Au(111).

Air-unstable magnetic aluminum phthalocyanine (AlPc) molecules are prepared by an on-surface metalation reaction of phthalocyanine with aluminum (Al) atoms on Au(111) in ultrahigh vacuum. Experiments and density functional theory calculations show that an unpaired spin is located on the conjugated isoindole lobes of the molecule rather than at the Al position.

Giant single-molecule anisotropic magnetoresistance at room temperature.

We report an electrochemically assisted jump-to-contact scanning tunneling microscopy (STM) break junction approach to create reproducible and well-defined single-molecule spintronic junctions. The STM break junction is equipped with an external magnetic field either parallel or perpendicular to the electron transport direction. The conductance of Fe-terephthalic acid (TPA)-Fe single-molecule junctions is measured and a giant single-molecule tunneling anisotropic magnetoresistance (T-AMR) up to 53% is observed at room temperature. Theoretical calculations based on first-principles quantum simulations show that the observed AMR of Fe-TPA-Fe junctions originates from electronic coupling at the TPA-Fe interfaces modified by the magnetic orientation of the Fe electrodes with respect to the direction of current flow. The present study highlights new opportunities for obtaining detailed understanding of mechanisms of charge and spin transport in molecular junctions and the role of interfaces in determining the MR of single-molecule junctions.

Extraordinary enhancement of Raman scattering from pyridine on single crystal Au and Pt electrodes by shell-isolated Au nanoparticles.

We used shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) to systematically study the adsorption of pyridine on low-index Au(hkl) and Pt(hkl) single crystal electrodes. Our gold-core silica-shell nanoparticles (Au@SiO(2) NPs) boost the intensity of Raman scattering from molecules adsorbed on atomically flat surfaces. The average enhancement factor reaches 10(6) for Au(110) and 10(5) for Pt(110), which is comparable to or even greater than that obtained for bare gold NPs (a widely adopted SERS substrate). 3D-FDTD simulations reveal that this large enhancement is due to the transfer of the "hotspots" from NP-NP gaps to NP-surface gaps. We also found that the SHINERS intensity strongly depends on the surface crystallographic orientation, with differences up to a factor of 30. Periodic DFT calculations and theoretical analysis of dielectric functions indicate that this facet-dependence is predominantly governed by the dielectric property of the surface. The results presented in this work may open up new approaches for the characterization of adsorbates and reaction pathways on a wide range of smooth surfaces.

Plasma-electrolysis synthesis of TiO2 nano/microspheres with optical absorption extended into the infra-red region.

A novel plasma-electrolysis method is introduced to synthesize high-quality TiO(2) nano/microspheres that exhibited excellent optical absorption covering the range from ultraviolet to infra-red. Both experimental and theoretical results show that the oxygen vacancies in the TiO(2) spheres are primarily responsible for this wide absorption.