An NO+ reactant ion source for ion mobility spectrometry

The major reactant ion in conventional ion mobility spectrometry (IMS) is the hydronium ion, H₃O⁺ which is produced in the usual ionization sources such as corona discharge or radioactive sources. Using the hydronium reactant ion, mostly the analytes with proton affinity higher than that of water are ionized. A broader range of compounds can be detected by IMS if other alternative ionization channels, such as charge transfer from NO⁺, are employed. In this work we introduce a simple and novel method for producing NO⁺ as the major reactant ion in IMS. This was achieved by adding neutral NO to the corona discharge ionization source. The neutral NO was prepared via an additional discharge in an air stream, flowing into the corona discharge source. A curtain plate was mounted in front of the corona discharge to prevent the influence of the analyte on the production of NO⁺. Using this technique, the reactant ion could easily and quickly switch between the H₃O⁺ and NO⁺. The performance of the new source was evaluated by recording ion mobility spectra of test compounds with both H₃O⁺ and NO⁺ reactant ions.     

Nitrate ion association with Sm3+ ion

A solvent extraction method withTBP as an extractant was used for the determination of the stability constantsK ₁ ^o for the SmNO ₃ ²⁺ complex, for different least approach distanceså of ions. It was established thatå=6.5 Å for SmNO ₃ ²⁺ .

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Zur Assoziation von Nitrat-Ion mit Sm³⁺

Zusammenfassung Die StabilitätskonstantenK ₁ ^o für den SmNO ₃ ²⁺ -Komplex bei verschiedenen Mindestannäherungsdistanzenå der Ionen wurden mittels einer Lösungsmittelextraktionsmethode mitTBP ermittelt. Der beste Wert fürå war 6.5 Å.

     

Hydrolysis and dimerization of Th4+ ion

Hydrolysis of Th(4+) in aqueous solution was studied by density functional theory (DFT) calculations. First, stable coordination numbers (CNs) of Th(4+) hydrolysis products were studied systematically, and it was found that the CN significantly decreases as a stepwise hydrolysis reaction proceeds. The fourth hydrolysis product Th(OH)4(0) has CN6 with an octahedron coordination. Th(OH)4(OH2)2(0) can readily form a dimer complex Th 2(OH)8(0) via a Th-OH-Th bridging through an exergonic reaction with a Gibbs energy change of -24.0 kJ/mol. Consequently, dimerization inhibits Th(OH)4(0) to stay as stable aqueous species. The calculated result is in agreement with the fact that there is no direct evidence to confirm the presence of Th(OH)4(0) while oligomeric species such as Th 4(OH)16(0) are presumably present. Similar calculations on the Th(4+) disulfato complex reveal that the CN and the average Th-O distance of Th(SO4)2(0) remain almost the same as those in the Th(4+) aquo ion, which is also in agreement with experimental data.     

Infrared predissociation spectrum of the CH+ ion

A high-resolution infrared spectrum of the CH⁺ ion has been recorded in the range 875–1095 cm⁻¹ using a laser/ion beam spectrometer. Eighty-seven transitions were detected by monitoring increased production of C⁺ fragment ions at resonance arising from predissociation of the upper states. Frequencies, linewidths, doublet splittings, relative intensities and upper state excess energies are reported for the transitions. A prediction of the spectrum, based on data from previous ab initio calculations and spectroscopic studies, was performed by using rotationally adiabatic potentials. Good qualitative agreement between the reported features of the observed spectrum and the prediction is found; the agreement suggests that the majority of the resonances are vibration-rotation transitions within the a ³Π state involving J = 20 to 40 and v = 7 to 12. The doublet splittings (16–672 MHz) are accounted for in terms of the proton nuclear hyperfine Fermi conctact interaction within this state.     

Nitrate ion association with Nd3+

The overall stability constantsK ₁ andK ₂ of NdNO ₃ ²⁺ and Nd(NO₃) ₂ ⁺ complexes were determined (K ₁=1.77;K ₂=1.28) using an extraction method with tri-n-butyl phosphate as the extractant. The ratio ₁/₂ of the stepwise stability constants is discussed. It was established that the Nd(NO₃) ₂ ⁺ complex was an outer-sphere ion pair.

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Die Assoziation von Nitrat-Ion mit Nd³⁺

Zusammenfassung Mittels einer Extraktionsmethode wurden die StabilitätskonstantenK ₁ undK ₂ von NdNO ₃ ²⁺ - und Nd(NO₃)⁺-Komplexen bestimmt (K ₁=1.77;K ₂=1.28; Tri-n-butylphosphat als Extraktionsmittel). Das Verhältnis ₁/₂ der stufenweisen Stabilitätskonstanten wird diskutiert. Es stellte sich heraus, daß der Nd(NO₃)⁺-Komplex als ein Outer-Shere-Ionenpaar vorliegt.

     

Nd3+ and Am3+ ion interactions with sulfate ion and their influence on NdPO4(c) solubility

The effects of Nd(III)/Am(III) complexation with sulfate were studied by 1) re-examining existing data for the Am–SO₄ system using more, advanced aqueous electrolyte models valid to high concentration to obtain reliable thermodynamic data for SO ₄ ^2– complexes or ion interactions with Nd³⁺ and Am³⁺ and 2) conducting experimental solubility studies of NdPO₄(c), an analog phase of AmPO ₄ (c), a possibly important phase in high level nuclear wastes, in the presence of SO ₄ ^2– to test the newly developed thermodynamic model and show the possible influence of sulfate in a repository environment. The data showed that the increase in the solubility of NdPO ₄ (c) resulted primarily from the increase in ionic strength. Slightly higher observed Nd concentrations in the presence of sulfate, as compared with concentrations predicted at the experimental ionic strengths, resulted from the weak complexes or ion interactions involving Nd ³⁺ –SO ₄ ^2– . The Pitzer ion interaction parameters, applicable to 0.5m sulfate, were obtained for Am ³⁺ –SO ₄ ^2– from a reinterpretation of known solvent extraction data. These parameters are also consistent with literature data for Am ³⁺ /Na⁺ exchange and solvent extraction in the presence of sulfate. When used for the analogous Nd ³⁺ –SO ₄ ^2– system to predict NdPO ₄ (c) solubility in the presence of sulfate, they provided excellent agreement between the predicted and the observed solubilities, indicating that they can be reliably used to determine Nd ³⁺ or Am ³⁺ ion interactions with SO ₄ ^2– in all ground waters where SO ₄ ^2– is less than 0.5m     

Degenerate rearrangement of 2H+-biphenylenonium ion

Conclusions The 2H⁺-biphenylenonium ion is formed when biphenylene is dissolved in the system HSO₃F-SbF₅-SO₂ClF, which undergoes degenerate rearrangement as the result of one of the hydrogen atoms of the CH₂ group shifting to the 3 position.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1199–1201, May, 1978.     

PEO-PVP blended Na+ ion conducting solid polymeric membranes

Polyethylene oxide (PEO)-polyvinylpyrrolidone (PVP) blended Na⁺ ion conducting solid polymeric membranes: (1?x) [75PEO:25NaPO₃] + x PVP, where 0 < x < 12 wt%, are reported. The polymeric blending was done using a solventfree hot-press method. Two orders of conductivity enhancement (σ ca. 1.07 × 10^?5 S·cm^?1) have been achieved with 3 wt% of PVP (i.e. the composition: [97(75PEO:25NaPO₃) + 3PVP]), from that of the pure host: (75PEO:25NaPO₃). The conductivity enhancement in PEO-PVP blended solid polymeric membranes have been explained by the ionic conductivity, ionic mobility and mobile ion concentration measurements. Materials characterization and polymer-salt complexation were done with the help of X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) studies. The temperature dependent conductivity studies have also been done to compute the activation energy (E _a) values from lg σ1/T Arrhenius plots. A solid state polymeric battery was fabricated by using optimum conducting composition of solid polymer electrolyte (SPE OCC), and some important cell parameters were also calculated from the discharge profile of the cell.     

Modifications of polypropylene surface properties by He+ ion implantation

A polypropylene (PP) modified by ethylene–propylene rubber (EPR) was treated in vacuo by α particles (with an energy of 400 keV) with fluences that varied from 10¹¹ to 10¹⁶ He⁺ cm^?2. Samples were investigated with attenuated total reflection Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, contact‐angle measurements, differential scanning calorimetry, swelling, nanoindentation, and friction techniques. After treatment, new chemical groups (carbonyl and vinyl bonds) appeared at the PP/EPR surface. These chemical modifications led to changes in the surface free energy of PP/EPR. Irradiation also modified the PP/EPR structure because crosslinking occurred after treatment for fluences above or equal to 5 × 10¹⁴ He⁺ cm^?2. Moreover, the PP melting temperature and enthalpy were greatly decreased for fluences above or equal to 10¹⁴ He⁺ cm^?2. The surface mechanical properties were also changed after treatment. Indeed, the friction coefficient decreased, whereas the hardness and Young's modulus drastically increased, after irradiation at higher fluences. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1183–1191, 2003     

BaTiO3:Sm3+ nanophosphor with K+ ion incorporation for modulating non-radiative transitions

Rare earth (RE) activated nanophosphors are the prime elements employed to manufacture light emitting diodes (LEDs) for the current solid state lighting (SSL) industry. The apparent lack of reddish orange emitting nanophosphors is proving to a constraint in the commercialization of the white light emitting diodes (WLEDs). Herein, the size of BaTiO₃ (BTO): Sm³⁺ and K⁺ co-activated BTO: Sm³⁺ nanophosphor, with an average particle size of 80 nm, have been produced by a modified sol gel technique. The synthesized nanophosphors emit a brilliant reddish-orange light when excited at 406 nm. The relative photoluminescence (PL) studies of Sm³⁺ doped BTO and Sm³⁺ doped BTO with K⁺ nanophosphor show that adding K⁺ doubles the intensity of the emitted light and improves the thermal stability in a significant way. The results of the research indicated that using the aforementioned nanophosphor in the future may be advantageous for solid-state lighting systems, including warm LEDs with cyan light chips.     

Depth profiling of polymer samples using Ga+ and C60+ ion beams

In this contribution, we focus on the use of C₆₀⁺ ions for depth profiling of model synthetic polymers: polystyrene (PS) and poly(methylmethacrylate) (PMMA). These polymers were spin coated on silicon wafers, and the obtained samples were depth‐profiled both with Ga⁺ ions and C₆₀⁺ ions. We observed an important yield enhancement for both polymers when C₆₀⁺ ions are used. More specifically, we discuss here the decrease in damage obtained with C₆₀, which is found to be very sensitive to the nature of the polymer. During the C₆₀⁺ sputtering of the PMMA layer, after an initial decrease, a steady state is observed in the secondary ion yield of characteristic fragments. In contrast, for PS, an exponential decrease is directly observed, leading to an initial disappearance cross section close to the value observed for Ga⁺. Though there is a significant loss of characteristic PS signal when sputtering with C₆₀⁺ ions beams, there are still significant enhancements in sputter yields when employing C₆₀⁺ as compared to Ga⁺. Copyright © 2008 John Wiley & Sons, Ltd.     

Molecular constants for the 1Σ+ ground state of the ArH+ ion

From the near equilibrium PNO-CEPA potential and dipole moment curves the following molecular constants for the ¹⁺ ground state of the ArH⁺ ion have been calculated: r _e = 1.286Å, _e = 2723 cm^–1, _{e e} = 56 cm^–1, D ₀ = 3.89 eV and ₀ = 2.384 D. The rotationless radiative lifetimes of the five lowest vibrational states are predicted to be 2.28, 1.2, 0.85, 0.64, 0.46 for ArH⁺ and 9.09, 4.71, 3.27, 2.55 and 2.11 for ArD⁺, respectively (all values are in milliseconds and in ascending order of the vibrational levels).Dedicated to Prof. Hermann Hartmann on the occasion of his 65th birthday.     

Studies on PAN-based carbon fibers irradiated by Ar+ ion beams

In this work, the effects of Ar+ ion beam irradiation on carbon fibers were studied using tensile and surface analytical techniques. The single-fiber pull-out test was executed in order to characterize the fiber/epoxy matrix interfacial adhesion. The Ar+ ion beam was irradiated using an ion-assisted reaction (IAR) method in reactive gas conditions under an oxygen environment with 1 x 10(16) ions/cm(2) Ar+ ion dose (ID), 6 sccm blown gas flow rate, and different ion beam energy intensities. From the experimental results, both the interfacial shear strength (IFSS) and fracture toughness (Gi) were found to increase with increasing Ar+ ion irradiation intensity. This was probably due to the fact that Ar+ ion beam irradiation on carbon fibers was effective in altering their surface physical chemistry and structural morphology, resulting in improved interfacial adhesion in the fiber/epoxy matrix. The reliability of single-fiber pull-out test data could be improved by statistical analysis using the Weibull distribution, which served to predict the variation of the mechanical interfacial properties in a composite system.     

Studies on ion exchange equilibria and kinetics VI. Prediction of ion exchange equilibria of UO 2 2+ −Na+−H+ ternary system

Experimental data are reported for the ion exchange equilibria of the binary systems UO ₂ ²⁺ –H⁺, UO ₂ ²⁺ –Na⁺ and Na⁺–H⁺, and of the ternary system UO ₂ ²⁺ –Na⁺–H⁺ on a strong acid cation exchange resin 001X7 at 25 °C. It is found that the equilibria for any pairs of ions are essentially the same in binary and ternary mixtures and that the prediction method proposed by our laboratory for SO ₂ ^2– –Cl^––NO ₃ ^– -201X7 strong base anion exchange resin system is also applicable to the ternary system studied in this paper. The predictions of the ternary system UO ₂ ²⁺ –Na⁺–H⁺ based solely on the binary data without using resin phase activity coefficients are consistent with the experimental data.     

Hydration of Y3+ ion: a Car-Parrinello molecular dynamics study

The solvation shell structure of Y3+ and the dynamics of the hydrated ion in an aqueous solution of 0.8 M YCl3 are studied in two conditions with and without an excess proton by using first principles molecular dynamics method. We find that the first solvation shell around Y3+ contains eight water molecules forming a square antiprism as expected from x-ray absorption near edge structure in both the conditions we examined. A detailed analysis relying upon localized orbitals reveals that the complexation of water molecules with yttrium cation leads to a substantial amount of charge redistribution particularly on the oxygen atoms, giving rise to the chemical shifts of approximately -20 ppm in 17O nuclear magnetic resonance relative to the computed nuclear shieldings of the bulk water.     

Amyloid-beta binds Cu2+ in a mononuclear metal ion binding site

Amyloid-beta (Abeta) peptide is the principal constituent of plaques associated with Alzheimer's disease and is thought to be responsible for the neurotoxicity associated with the disease. Metal ions have been hypothesized to play a role in the formation and neurotoxicity of aggregates associated with Alzheimer's disease (Bush, A. I.; et al. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 11934). Elucidation of the chemistry through which transition-metal ions participate in the assembly and toxicity of Abeta oligomers is important to drug design efforts if inhibition of Abeta containing bound metal ions becomes a treatment for Alzheimer's disease. In this paper, we report electron paramagnetic resonance (EPR) spectroscopic characterization of Cu(2+) bound to soluble and fibrillar Abeta. Addition of stoichiometric amounts of Cu(2+) to soluble Abeta produces an EPR signal at 10 K with observable Cu(2+) hyperfine lines. A nearly identical spectrum is observed for Abetafibrils assembled in the presence of Cu(2+). The EPR parameters are consistent with a Type 2 Cu(2+) center with three nitrogen donor atoms and one oxygen donor atom in the coordination sphere of Cu(2+): g( parallel) = 2.26 and A( parallel) = 174 +/- 4 G for soluble Abeta with Cu(2+), and g( parallel) = 2.26 and A( parallel) = 175 +/- 1 G for Abeta fibrils assembled with Cu(2+). Investigation of the temperature dependence of the EPR signal for Cu(2+) bound to soluble Abetaor Cu(2+) in fibrillar Abeta shows that the Cu(2+) center displays normal Curie behavior, indicating that the site is a mononuclear Cu(2+) site. Fibrils assembled in the presence of Cu(2+) contain one Cu(2+) ion per peptide. These results show that the ligand donor atom set to Cu(2+) does not change during organization of Abetamonomers into fibrils and that neither soluble nor fibrillar forms of Abeta(1-40) with Cu(2+) contain antiferromagnetically exchange-coupled binuclear Cu(2+) sites in which two Cu(2+) ions are bridged by an intervening ligand.     

Very accurate potential energy curve of the He2+ ion

A very accurate ground-state potential energy curve (PEC) of the He(2)(+) molecule is calculated with 1200 explicitly correlated Gaussian functions with shifted centers in the range between 0.9 and 100 a(0). The calculations include the adiabatic corrections determined for the (3)He(4)He(+), (3)He(2)(+), and (4)He(2)(+) isotopologues. The absolute accuracy of the PEC is better than 0.05 cm(-1) and that of the adiabatic corrections is around 0.01 cm(-1). The depths of the PECs augmented with the adiabatic corrections for the three isotopologues are: 19 956.708 cm(-1) for (4)He(2)(+), 19 957.054 cm(-1) for (3)He(4)He(+), and 19 957.401 cm(-1) for (3)He(2)(+). The rovibrational energies are also determined. For (3)He(4)He(+) the computed rovibrational transitions corresponding to the ν = 1-0 band differ from the experiment by less than 0.005 cm(-1). For the rovibrational transitions corresponding to the ν = 23-22 band the difference is around 0.012 cm(-1). Presently, this represents the best agreement between theory and experiment for He(2)(+).     

Low energy 13C+ and 13C2+ ion irradiation of water ice

In this paper we report the results of the first experimental study of the irradiation of low temperature water ice (30 and 90 K) using low energy (4 keV) 13C+ and 13C2+ ions. 13CO(2) and H2O(2) were readily formed within the H2O ice with the product yield and growth rate observed to be highly dependent on both the sample temperature and ion charge state.     

Diffusion of Cs+ and Zn2+ through Nafion-117 ion exchange membrane

This paper discusses the diffusion of Cs⁺ and Zn²⁺ ions through Nafion-117 cation exchange membrane using radiotracer technique. The validity of the Donnan's equation is checked for these ions using⁶⁵Zn and¹³⁷Cs radiotracers. The paper also discusses the diffusion of Cl^– and I^– anions studied by using³⁶Cl and¹³¹I radiotracers. The probable mechanism of diffusion of these anions in the presence of Zn²⁺ cations is suggested.