Electron-Impact Mass Spectrometry of PTCDA Molecules in the Gas Phase

The complete and dissociative ionizations of a 3,4,9,10-perylene-tetracarboxylic-dianhydride (C24H8O6, PTCDA) molecule in the gas phase have been studied, by using electron-impact mass spectrometry in an energy interval of 5–90 eV. The molecule is found to decay into the following fragment ions: the perylene core C20H8+ and its half C10H4+, as well as CO+, CO2+ , and O+ ions. The energy dependences of the cross-sections of the complete ionization of a PTCDA molecule and its fragment ions are analyzed. The energy of the complete ionization of a PTCDA molecule and the energies, at which its fragments appear, are determined. The temperature dependences of the formation of the most intensive fragment ions are measured, by using 80-eV electrons in a temperature interval of 320–500 K.

Analyses of the power generation performance and the non-equilibrium plasma of a disk MHD generator

Recently, closed cycle MHD power generation system studies have been focused on improving the isentropic efficiency and the enthalpy extraction ratio. By reducing the crosssection area ratio of the disk MHD generator, it is believed that a high isentropic efficiency can be achieved with the same enthalpy extraction. In this study, the results relating to a plasma state which takes into account the ionization instability of non-equilibrium seeded plasma is added to the theoretical prediction of the relationship between enthalpy extraction and isentropic efficiency. As a result, the electron temperature, which reaches the seed complete ionization state without the growth of ionization instability, can be realized at a relatively high seed fraction condition. However, the upper limit of the power generation performance is suggested to remain lower than the value expected in the low seed fraction condition. It is also suggested that a higher power generation performance may be obtained by implementing the electron temperature range, which reaches the seed complete ionization state at a low seed fraction.

Synthesis of multicomponent metallic layers during impulse plasma deposition

Pulsed plasma in the impulse plasma deposition (IPD) synthesis is generated in a coaxial accelerator by strong periodic electrical pulses, and it is distributed in a form of energetic plasma packets. A nearly complete ionization of gas, in these conditions of plasma generation, favors the nucleation of new phase of ions and synthesis of metastable materials in a form of coatings which are characterized by amorphous and/or nanocrystalline structure. In this work, the Fe–Cu alloy, which is immiscible in the state of equilibrium, was selected as a model system to study the possibility of formation of a non-equilibrium phase during the IPD synthesis. Structural characterization of the layers was done by means of X-ray diffraction and conversion-electron Mössbauer spectroscopy. It was found that supersaturated solid solutions were created as a result of mixing and/or alloying effects between the layer components delivered to the substrate independently and separately in time. Therefore, the solubility in the Fe–Cu system was largely extended in relation to the equilibrium conditions, as described by the equilibrium phase diagram in the solid state.

Influence of micelle properties on micellar-enhanced ultrafiltration for chromium recovery

An investigation of micelle properties on the recovery of chromium for micellar enhanced ultrafiltration (MEUF) process was conducted using cationic surfactant of cetyltrimethylammonium bromide (CTAB). The relationship between degree of ionization, micellar sizes and chromium removal were determined in this study. The results showed that the complete ionization for CTA+ and Br− was observed for CTAB lower than 0.72 mM and aggregation initiated at concentration of CTAB higher than 0.72 mM to yield attraction of counterion. The micellar sizes increased with increase in concentration of CTAB (higher than 4.02 mM) to generate micron-sized micelles. The distribution of micellar sizes was used to estimate the molecular weight cutoff of membrane used in the MEUF process. As chromium was added into aqueous CTAB solution, the chromate was dominant and bound on the micellar surface instead of Br−. Moreover, the presence of micelle formed a gel-layer to slightly shrink the membrane pore, therefore, UF membrane of 30k Da molecular weight cutoff (pore size ≈ 7.9 nm) was selected in the MEUF process to achieve the removal efficiency of Cr(VI) higher than 95%.

LiBC – Synthesis, Electrochemical and Solid-state NMR Investigations

LiBC was synthesized from the elements in a sealed niobium ampoule. It represents a totally intercalated heterographite with a structural relationship to graphite, the most commonly used anode material for lithium ion batteries. Since LiBC could accommodate three times as much lithium as graphite, its electrochemical properties in the anode and the cathode voltage range were investigated. However, LiBC did show poor performance both as an anode and as a cathode material. The unfavorable characteristics of LiBC with respect to electrochemical de-lithiation and re-insertion can be rationalized on the basis of nuclear magnetic resonance results. 7Li and 6Li isotropic chemical shifts are consistent with complete ionization of the lithium species. Variable-temperature static 7Li NMR lineshapes indicate that the mobility of the lithium ions is rather restricted, even at temperatures up to 500 K. The 11B and 13C NMR parameters are consistent with those measured in sp2-hybridized boron/carbon networks and also support the ionic bonding model.

Compact Modeling of the Temperature Dependence of Parasitic Resistances in SiGe HBTs Down to 30 K

In this paper, we investigate the physics and modeling of temperature dependence of various parasitic resistances in SiGe heterojunction bipolar transistors down to 30 K. Carrier freezeout is shown to be the dominant contributor to increased resistances at cryogenic temperatures for lightly-doped and moderately-doped regions, whereas the temperature dependence of the mobility is the dominant contributor to the temperature dependence of heavily-doped regions. Two incomplete ionization models, the classic model with a doping dependent activation energy and the recent model of Altermatt , are shown to underestimate and overestimate incomplete ionization rate below 100 K for intrinsic base doping, respectively. Analysis of experimental data shows that the bound state fraction factor is temperature dependent and including this temperature dependence enables compact modeling of resistances from 30 to 300 K for moderately-doped regions. For heavily-doped regions, a dual power law mobility approximation with complete ionization is shown to work well down to 30 K. An alternative approach is also presented for heavily-doped resistors which allows one to use the same model equation for all regions.

IONIZATION IN A 1-DIMENSIONAL DIPOLE MODEL

We study the evolution of a one-dimensional model atom with δ-function binding potential, subjected to a dipole radiation field E(t)x with E(t) a 2π/ω-periodic real-valued function. We prove that when E(t) is a trigonometric polynomial, complete ionization occurs, i.e. the probability of finding the electron in any fixed region goes to zero as t → ∞. For ψ(x, t = 0) compactly supported and general periodic fields, we decompose ψ(x, t) into uniquely defined resonance terms and a remainder. Each resonance is 2π/ω periodic in time and behaves like the exponentially growing Green's function near x = ±∞. The remainder is given by an asymptotic power series in t-1/2 with coefficients varying with x.

Synthesis, Spectroscopic, and Anticancerous Properties of Mixed Ligand Palladium(II) and Silver(I) Complexes with 4,6-Diamino-5-hydroxy-2-mercaptopyrimidine and 2,2′-Bipyridyl

Synthesis of two new water-soluble mixed ligand [Pd(bpy)(dahmp)]Cl and [Ag(bpy)(Hdahmp)]NO3 complexes (dahmp and Hdahmp are the deprotonated monoanion and the protonated neutral 4,6-diamino-5-hydroxy-2-mercaptopyrimidine, resp.) is reported. The composition of the reported complexes was discussed on the bases of IR, H1 NMR, and mass spectra, as well as conductivity and thermal measurements. The reported complexes display a significant anticancer activity against Ehrlich ascites tumor cells (EACs). The higher activity of these complexes with their higher conductivity values corresponds to their complete ionization in aqueous solution.