33S and 13C hyperfine interactions in the single-crystal EPR spectra of 63Cu(II) bis(diethyl-dithiocarbamate)

A detailed analysis of the 33S and 13C ligand hyperfine interactions observed in the single-crystal EPR spectra of 63Cu-labelled copper(II)bis(diethyl-dithiocarbamate), diamagnetically diluted by the corresponding Ni(II)-complex, is reported. The 33S hyperfine tensors are nearly axial symmetric; the unique axes are found to lie along the CuS bond directions. The observation of two different sets of 33S splitting parameters is in agreement with the presence of a rhombic distortion of the planar ligand field. The 13C hyperfine tensor is isotropic within experimental error. The bonding situation of the electronic ground state is discussed. In order to explain the unusually small linewidths observed the electron spin-lattice relaxation time was measured in the temperature-range 2 ≤ T ≤ 77 K. © 1977

Electron spin-lattice relaxation of Cu(II) in Zn(II)-bis(diethyl-diselenocarbamate) single crystals

Using the pulse saturation method the spin-lattice relaxation rate T1 -1 for Cu(II) in Zn(II)-bis(diethyl-diselenocarbamate) was measured in the temperature range 1.5 < T < 33 K. From the T-dependence of T1 -1 the Debye temperature of the host crystal was obtained. The angular dependence of T1 -1 as well as the influence of the hyperfine interaction on T1 -1 are discussed. © 1974

A single crystal EPR study of the platinum (III)-bis (maleonitriledithiolate)-monoanion

A first single crystal EPR study of a Pt3+ chelate-tetrabutylammonium-bis (maleonitriledithiolato) platinate (III)-diamagnetically diluted by the corresponding gold (III) chelate is reported. The spectra are described by a rhombic spin Hamiltonian. For some orientations of the magnetic field 33S superhyperfine splitting was observed. The 33S tensor has the maximum value perpendicular to the plane of the complex supporting a 2B3g ground state in which the half-filled out-of-plane π molecular orbital is extensively delocalized over the ligands. Furthermore, the electron spin-lattice relaxation of the Pt3+ complex was measured in the temperature range 4.2 ≤ T ≤ 16 K. Spin-lattice interactions were found to be mainly responsible for the linewidth in the Pt3+ spectra, which is larger by a factor 2 than those observed for Pd3+ and Ni3+ in the same host complex [Au(mnt)2]-. © 1977

Spin-lattice relaxation of exchange-coupled Cu2+-Cu2+ pairs and single Cu2+ ions in crystals of zinc (II) bis(diethyl-dithiocarbamate)

Detailed investigations of the spin-lattice relaxation of single Cu 2+ ions and Cu2+-Cu2+ pairs in zinc (II) bis(di- ethyl-dithiocarbamate) single crystals are reported. The measurements were made in the temperature range 1.5<T<35K at v=28.8 and 9.0 GHz using the pulse saturation and the spin-echo method, respectively. At T<5K the single-ion relaxation is defined by direct processes; at higher temperatures two-phonon Raman processes were observed. In the range 4<T<12K the data can be fitted by an Orbach-Aminov process. A calculation of the single-ion relaxation rate for the direct process has been made. Also the pair relaxation rate in the same range was calculated considering the rate equations of the populations of the triplet state. From the temperature dependence of the Orbach-Aminov process the isotropic exchange integral was derived. Low-temperature EPR measurements provided the signs of the D-tensor and of the exchange integral. From the temperature dependence of the single-ion Raman relaxation rate the Debye temperature of the host crystal was estimated. For exchange coupled pairs the anomalous frequency dependence of T1 -1 was observed

Random matrix description of decaying quantum systems

This contribution describes a statistical model for decaying quantum systems (e.g. photo-dissociation or -ionization). It takes the interference between direct and indirect decay processes explicitely into account. The resulting expressions for the partial decay amplitudes and the corresponding cross sections may be considered a many-channel many-resonance generalization of Fano's original work on resonance lineshapes [Phys. Rev 124, 1866 (1961)]. A statistical (random matrix) model is then introduced. It allows to describe chaotic scattering systems with tunable couplings to the decay channels. We focus on the autocorrelation function of the total (photo) cross section, and we find that it depends on the same combination of parameters, as the Fano-parameter distribution. These combinations are statistical variants of the one-channel Fano parameter. It is thus possible to study Fano interference (i.e. the interference between direct and indirect decay paths) on the basis of the autocorrelation function, and thereby in the regime of overlapping resonances. It allows us, to study the Fano interference in the limit of strongly overlapping resonances, where we find a persisting effect on the level of the weak localization correction.Comment: 16 pages, 2 figure

Ordered structure of FeGe₂ formed during solid-phase epitaxy

Fe3Si/Ge(Fe,Si)/Fe3Si thin-film stacks were grown by a combination of molecular beam epitaxy and solid-phase epitaxy (Ge on Fe3Si). The stacks were analyzed using electron microscopy, electron diffraction, and synchrotron x-ray diffraction. The Ge(Fe,Si) films crystallize in the well-oriented, layered tetragonal structure FeGe2 with space group P4mm. This kind of structure does not exist as a bulk material and is stabilized by the solid-phase epitaxy of Ge on Fe3Si. We interpret this as an ordering phenomenon induced by minimization of the elastic energy of the epitaxial film

Structural properties of Co2TiSi films on GaAs(001)

Co2TiSi films were grown by molecular beam epitaxy on GaAs(001) and analyzed using reflection high-energy electron diffraction, and electron microscopy. In addition, X-ray diffraction was combined with lattice parameter calculations by density functional theory comparing the L21 and B2 structures and considering the influence of non-stoichiometry. Columnar growth is found and attributed to inhomogeneous epitaxial strain from non-random alloying. In films with thicknesses up to 13 nm, these columns may be the origin of perpendicular magnetization with the easy axis perpendicular to the sample surface. We found L21 and B2 ordered regions, however the [Co]/[Ti]-ratio is changing in dependence of the position in the film. The resulting columnar structure is leading to anisotropic B2-ordering with the best order parallel to the axes of the columns

The Role of the Subgenual Anterior Cingulate Cortex and Amygdala in Environmental Sensitivity to Infant Crying

This work was supported by the Swiss National Science Foundation (SNF): Grant 51A240-104890 to FHW and ES, and the Swiss National Science Foundation (SNF): Grant PA00P1_145418 to IM and the Freiwillige Akademische Gesellschaft to IM