Specific features of the charge and mass transfer in a silver-intercalated hafnium diselenide

The specific features of the charge transfer in intercalated samples of Ag _x HfSe₂ have been studied for the first time by alternating current (ac) impedance spectroscopy. It has been found that relaxation processes in an ac field are accelerated with increasing silver content in the samples. The complex conductivity (Y) shows a frequency dispersion described by power law Y ～ ω _s , which is characteristic of the hopping conductivity mechanism. The Ag _x HfSe₂ compounds demonstrate shorter relaxation times as compared to those observed in hafnium diselenide intercalated with copper atoms, and this fact indicates that the charge carrier mobility in the silver-intercalated compounds is higher. The possibility of silver ion transfer in Ag _x HfSe₂ is confirmed by the measurements performed by the method of electrochemical cell emf.     

Phonon-induced charge transfer in ZnO

Using the high-resolution 93.3 keV Mössbauer transition in ⁶⁷Zn we studied the temperature dependence of the center shift in ZnO single crystals between 4.2 and 77.3 K. Already at low temperature dependent isomer shift is present. The latter originates from phonon-induced electron transfer from zinc to oxygen     

Band structure in104Ag

The level structure of¹⁰⁴Ag has been studied through the¹⁰³Rh (α, 3nγ) reaction at E_α=40 and 45 MeV. The principal features of the proposed level scheme are in agreement with those obtained earlier through heavy ion reaction. Two quasiparttcle-plus-rotor model calculation has been performed, and the results are compared with experimental data.     

Co掺杂ZnO薄膜的局域结构和电荷转移特性研究

采用磁束缚电感耦合等离子体溅射沉积法在不同的氧气分压下制备了Zn_0.95Co_0.05O和Zn_0.94Co_0.05Al_0.01O薄膜.利用X射线吸收精细结构技术对薄膜O-K,Co-K和Co-L边进行了局域结构研究,结果表明：Co²⁺取代了四配位晶体场中的Zn²⁺而未改变ZnO的六方纤锌矿结构,高真空条件下制备的薄膜 关键词： Co掺杂ZnO 稀磁半导体 X射线吸收精细结构 共振非弹性X射线散射     

Non-adiabatic interactions in charge transfer collisions

An analysis of the charge transfer mechanism in the collision of multiply charged ions with molecular and biomolecular targets is performed, considering the non-adiabatic interactions between the molecular states involved. Collisions of doubly charged C ²⁺ ions on small molecular targets, CO and OH, have been investigated, together with the analysis of charge transfer between C ⁴⁺ ions on uracil and halouracil biomolecular targets. The process is studied theoretically by means of ab-initio molecular calculations followed by a semi-classical treatment of the collision dynamics. The influence of rotational couplings is discussed with regard to the collision energy. Strong anisotropic and vibration effects are pointed out.     

Orbital ordering in charge transfer insulators

We discuss a new mechanism of orbital ordering, which in charge transfer insulators is more important than the usual exchange interactions and which can make the very type of the ground state of a charge transfer insulator, i.e., its orbital and magnetic ordering, different from that of a Mott-Hubbard insulator. This purely electronic mechanism allows us to explain why orbitals in Jahn-Teller materials typically order at higher temperatures than spins, and to understand the type of orbital ordering in a number of materials, e.g., K2CuF4, without invoking the electron-lattice interaction.     

Band structure of AlSb

A combination of the pseudopotential method with thek. p method was used to calculate the complete band structure of AlSb. The pseudopotential form factors were determined by fitting to reliably assigned optical transition energies. Optical critical points and effective masses were evaluated and compared with experimental data so far as possible.This work was performed in the Arbeitsgemeinschaft A_IIIB_V-Halbleiter of the Karl-Marx University Leipzig. The authors are indebted to Dr. K.Unger for stimulating discussions.     

Band structure of InN

The energy band structure of wurtzite-structure semiconductive InN is predicted using empirical nearest-neighbor tight-binding theory. The tight-binding parameters are extrapolated from those of zincblende InP, InAs, and InSb by using empirical rules for the dependences of the parameters on bond length and on row of the Periodic Table. The predicted band gap is direct and agrees well with the data for this potential orange light-emitter. It is suggested that zincblende InN, if it can be grown, also will have a band-gap near 2 eV.     

Measurements of charge transfer efficiency in a proton-irradiated swept charge device

Charged Coupled Devices (CCDs) have been successfully used in several low energy X-ray astronomical satellites over the past two decades. Their high energy resolution and high spatial resolution make them a perfect tool for low energy astronomy, such as observing the formation of galaxy clusters and the environment around black holes. The Low Energy X-ray Telescope (LE) group is developing a Swept Charge Device (SCD) for the Hard X-ray Modulation Telescope (HXMT) satellite. A SCD is a special low energy X-ray CCD, which can be read out a thousand times faster than traditional CCDs, simultaneously keeping excellent energy resolution. A test method for measuring the charge transfer efficiency (CTE) of a prototype SCD has been set up. Studies of the charge transfer inefficiency (CTI) with a proton-irradiated SCD have been performed at a range of operating temperatures. The SCD is irradiated by 3×10⁸cm^-2 10 MeV protons.     

Characteristic features of charge transfer in the interaction between sensitizer molecules and AgCl(I) molecules

We have used flash luminescence stimulation and photoinduced emission methods to study deep impurity states of AgCl(I) microcrystals with adsorbed organic cationic and anionic dye molecules. We have observed that when these molecules interact with the crystal, charge transfer occurs simultaneously from different orbitals and the transfer occurs differently from each orbital: some orbitals of the molecule pick up a negative charge, others at the same time give up a negative charge. We hypothesize that the type of transfer is determined by the overall charge.     

Polaron assisted charge transfer in model biologicalsystems

We use a tight binding Hamiltonian to simulate the electron transfer from an initialcharge-separating exciton to a final target state through a two-arm transfer model. Thestructure is copied from the model frequently used to describe electron harvesting inphotosynthesis (photosystems I). We use this network to provide proof of principle fordynamics, in quantum system/bath networks, especially those involving interferencepathways, and use these results to make predictions on artificially realizable systems.Each site is coupled to the phonon bath via several electron-phonon couplings. The assumedlarge energy gaps and weak tunneling integrals linking the last 3 sites give rise to“StarkWannier like” quantum localization; electron transfer to the target cluster becomesimpossible without bath coupling. As a result of the electron-phonon coupling, localelectronic energies relax when the site is occupied, and transient polaronic states areformed as photo-generated electrons traverse the system. For a symmetric constructivelyinterfering two pathway network, the population is shared equally between two sets ofequivalent sites and therefore the polaron energy shift is smaller. The smaller energyshift however makes the tunnel transfer to the last site slower or blocks it altogether.Slight disorder (or thermal noise) can break the symmetry, permitting essentially a “onepath”, and correspondingly more efficient transfer.     

Heat-induced charge transfer in cobalt iron cyanide

The heating of Co(2+) ferricyanide above 80 °C induces an inner charge transfer from Co(2+) towards Fe(III) to form the mixed valence system Co(2+)Co(III) ferri- ferro-cyanide. This charge transfer takes place preserving the material framework and forming a solid solution of the initial and final species. The cell edge of the cubic cell (Fm-3m) of this solid solution follows a regular variation with the material composition. This mixed valence system was characterized using X-ray diffraction, infrared, thermo-gravimetric, Mössbauer and magnetic measurements. Its formation is easily detected by the appearance of an intermediate ν(CN) absorption band in the infrared spectra at around 2120 cm⁻¹, 40 cm⁻¹ below and above the observed frequency for this vibration in Co(2+) ferri- and ferro-cyanide, respectively.     

XPS-investigation of intramolecular charge transfer in polynitro-aminobenzenes

It has been shown that the shake-up energy ΔE¹, which depends on the ionization potential (IP) of the neutral (poly)nitro-aminobenzenes, vanishes for IP≈ 8.4 eV. The λ values, which measure the contribution of intramolecular charge-transfer configurations in the molecules-in-molecules models correlate rather well with the difference E_II- E₁, i.e., the difference of the peak positions corresponding to lower and higher binding energies.     

Surface magnetism in organic charge transfer salts

We have investigated the magnetic properties of the charge transfer salts Qn(TCNQ)₂, Cs₂(TCNQ)₃ and TTF—TCNQ in the form of single crystals and after strong pressing or grinding to a fine powder, which introduces lattice defects and increases the surface area. It is found that for the former two compounds pressing or grinding leads to a non-linear, saturating component in the magnetisation field curves, whereas the effect is absent for TTF—TCNQ. It is suggested that this behaviour could arise from strongly coupled localised spins at the surface, i.e. surface magnetism in these materials.     

Quasidegenerate self-trapping in one-dimensional charge transfer exciton

The self-trapping by the nondiagonal particle-phonon interaction between two quasidegenerate energy levels of the excitonic system is studied. We propose this is realized in the charge-transfer exciton, where the directions of the polarization give the quasidegeneracy. It is shown that this mechanism, unlike the conventional diagonal one, allows a coexistence and resonance of the free and self-trapped states even in one-dimensional systems and a quantitative theory for the optical properties (light absorption and time-resolved luminescence) of the resonating states is presented. This theory gives a consistent resolution for the long-standing puzzles in quasi-one-dimensional compound A-PMDA.     

Measurement of charge transfer in electrostatic discharges

Experimental studies are reported that show the errors that arise in using unshielded probes for measuring charge transfer in electrostatic discharges. Comparable errors will apply where unshielded probes are used for current flow measurements. Errors are avoided by using shielded probes with an appropriate charge measurement circuit. These results are relevant to the design of probes to be included in IEC Standards.