Phthalocyanine reactivity and interaction on the 6H-SiC(0001)-(3×3) surface by core-level experiments and simulations

The adsorption of phthalocyanine (H2Pc) on the 6H-SiC(0001)-(3×3) surface is investigated using X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure spectroscopy (NEXAFS), and density functional theory (DFT) calculations....

Spin Polarization, Electron-Phonon Coupling, and Zero-Phonon Line of the NV Center in 3C-SiC

The nitrogen-vacancy (NV) center in 3C-SiC, the analog of the NV center in diamond, has recently emerged as a solid-state qubit with competitive properties and significant technological advantages. Combining first-principles calculations and magnetic resonance spectroscopy, we provide thorough insight into its magneto-optical properties. By applying resonantly excited electron paramagnetic resonance spectroscopy, we identified the zero-phonon absorption line of the ³A₂ → ³E transition at 1289 nm (within the telecom O-band) and measured its phonon sideband, the analysis of which reveals a Huang-Rhys factor of S = 2.85 and a Debye-Waller factor of 5.8%. The low-temperature spin-lattice relaxation time was found to be exceptionally long (T₁ = 17 s at 4 K). All these properties make NV in 3C-SiC a strong competitor for qubit applications. In addition, the strong variation of the zero-field splitting in the range 4-380 K allows its application for nanoscale thermal sensing.

Dual switchable molecular tweezers incorporating anisotropic MnIII-salphen complexes

An alternative strategy for the synthesis of terpyridine based switchable molecular tweezers has been developed to incorporate anisotropic Mn(iii)-salphen complexes. The free ligand was synthesized using a building block strategy based on Sonogashira coupling reactions and was then selectively metalated with manganese in a last step. The conformation of the tweezers was switched from an open 'W' shaped form to a closed 'U' form by Zn(ii) coordination to the terpyridine unit bringing the two Mn-salphen moieties in close spatial proximity as confirmed by X-ray crystallography. An alternate switching mechanism was observed by the intercalation of a bridging cyanide ligand between the two Mn-salphen moieties that resulted in the closing of the tweezers. These dual stimuli are attractive for achieving multiple controls of the mechanical motion of the tweezers. A crystallographic structure of unexpected partially oxidized closed tweezers was also obtained. One of the two Mn-salphen moieties underwent a ligand-centered oxidation of an imino to an amido group allowing an intramolecular Mn-Oamide-Mn linkage. The magnetic properties of the manganese(iii) dimers were investigated to evaluate the magnetic exchange interaction and analyze the single molecule magnet behavior.

Six States Switching of Redox-Active Molecular Tweezers by Three Orthogonal Stimuli

A six level molecular switch based on terpyridine(Ni-salphen)₂ tweezers and addressable by three orthogonal stimuli (metal coordination, redox reaction, and guest binding) is reported. By a metal coordination stimulus, the tweezers can be mechanically switched from an open "W"-shaped conformation to a closed "U"-shaped form. Theses two states can each be reversibly oxidized by the redox stimulus and bind to a pyrazine guest resulting in four additional states. All six states are stable and accessible by the right combination of stimuli and were studied by NMR, XRD, EPR spectroscopy, and DFT calculations. The combination of the supramolecular concepts of mechanical motion and guest binding with the redox noninnocent and valence tautomerism properties of Ni-salphen complexes added two new dimensions to a mechanical switch.

Mechanical switching of magnetic interaction by tweezers-type complex

An original approach using a mechanical motion to control the magnetic interaction between the two spin centers of terpy(Cu–salphen)₂ complexes is presented.

Photomagnetic molecular and extended network Langmuir–Blodgett films based on cyanide bridged molybdenum–copper complexes

The present manuscript describes two types of cyanide bridged molybdenum–copper photomagnetic films obtained by the Langmuir–Blodgett technique.

Identification of the nitrogen split interstitial (N-N)(N) in GaN

Combining electron paramagnetic resonance, density functional theory, and positron annihilation spectroscopy (PAS), we identify the nitrogen interstitial defect in GaN. The isolated interstitial is unstable and transforms into a split interstitial configuration (N-N)(N). It is generated by particle irradiation with an introduction rate of a primary defect, pins the Fermi level at E(C)-1.0 eV for high fluences, and anneals out at 400 °C. The associated defect, the nitrogen vacancy, is observed by PAS only in the initial stage of irradiation.

Identification of the carbon dangling bond center at the 4H-SiC/SiO(2) interface by an EPR study in oxidized porous SiC

We report the observation of a paramagnetic interface defect in thermally oxidized porous n-type doped 4H-SiC/SiO(2). Based on its axial symmetry and resolved hyperfine interactions it is attributed to an sp(3) carbon dangling bond center situated at the SiC side of the interface. This center is electrically active and pins the Fermi level in the oxidized samples. No silicon related paramagnetic dangling bond centers are observed. The formation of dangling bond centers seems to be related to interstitial oxygen diffusion at the interface during the oxidation process.

SB7: the new bending-magnet double-headed dragon beamline at SuperACO

A new beamline is now operational at LURE on bending-magnet 7 of the SuperACO storage ring in Orsay. The monochromator is of the ;dragon' type, designed to work in the energy range 150-1500 eV, and is equipped with a double vertical focusing mirror in order to allow for fast switching of light polarization. In this paper the results of photoion-yield experiments performed on N(2), Ar and Ne gases are presented. The observed resonance structures enable us to determine the available energy resolution: a resolving power higher than 8500 is obtained at the Ar 2p, N 1s and Ne K-edges when using all the optical elements at full aperture. The total flux as a function of the measured photon energy resolution and the characterization of the double-head behaviour in delivering circularly polarized light are reported.