Influence of repeller potential on ion-molecule reactions in methane and carbon tetrafluoride mixtures

Investigations of ion-molecule reactions were performed for methane-carbon tetrafluoride mixtures of different compositions. Concentration of methane in these mixtures ranged from 10% to 90% (at 10% increment) and total mixture pressure was fixed at 13.3 Pa. Measurements were made using a quadrupole mass spectrometer with a high-pressure ion source. Primary ions CH₄⁺, F⁺, CF⁺ and CF₃⁺ were produced by electrons with energy of 300 eV. Secondary ions CH₅⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, C₂H₇⁺ and CF₃⁺ were observed as the result of ion-molecule reactions.The influence of repeller potential on ion-molecule reactions efficiency was examined.     

Ion–molecule reactions in mixtures of ethane with carbon tetrafluoride

Ion–molecule reactions have been measured for the ethane–carbon tetrafluoride mixtures of different compositions using a quadrupole mass spectrometer with a high-pressure ion source. Concentration of ethane in these mixtures ranged from 10% to 90% (at 10% increment). The following primary and secondary ions: CH₃⁺, F⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, C₂H₆⁺, C₃H₅⁺, C₃H₇⁺, C₄H₇⁺, C₄H₉⁺, C₄H₁₀⁺, C₄H₁₁⁺ and CF₃⁺ were observed. Relative ion current intensities for primary and secondary ions are presented as a function both of total mixture pressure and concentration of carbon tetrafluoride in the mixture. Primary ions were produced by electrons with the energy of 300 eV. Potential of repeller electrode inside the ion source collision chamber was fixed at 5 V for all measurements. The total mixture pressure was changed from 0.7 to 26.6 Pa. Schemes of ion–molecule reactions were proposed.     

High pressure investigations of ion – Molecule reactions in a mixture of C3H8 and Ne

The gas phase reactions of positive Ne⁺ ions produced from neon with neutral propane have been studied with the use of a quadrupole mass spectrometer with a high pressure ion source. The measurements were performed in a mixture of 1% C₃H₈ and 99% Ne in the pressure range 1.33–40.00 Pa. The fractional abundances I_i/ΣI_i (relative intensity of the ion currents) of dominant C₂H₂⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, C₃H₅⁺, C₃H₇⁺ ions and neon ions have been determined as a function of the gas mixture pressure and of the repeller electrode potential ranged from 3 V to 10 V.     

Kinetic energy release and mean life time of metastable ions produced from C3H3N

Metastable ions C₃H_nN⁺ (n = 1, 2 or 3) and C₂H₂⁺ produced by electron impact on the neutral C₃H₃N (acrylonitrile) undergo metastable decay reactions resulting in the fragment ions C₃H_mN⁺ (m = 1, 2) or C₂H₂⁺. We have monitored these reactions in a double focusing mass spectrometer of reversed B-E geometry. To identify the fragment ions and determine their kinetic energy release distribution (KERD), the mass-analyzed ion kinetic energy (MIKE) scan technique was utilized. For the above mentioned ions we obtained average KER values ranging from 9 up to 23 meV. Moreover, the fractions of decaying ions were measured. We have found the existence of two states of the metastable C₂H₂⁺ ion, one with a short life time of about 0.27 μs and the other one which is most likely a completely stable ion state.     

High-pressure mass spectrometric investigations of ion-molecule reactions in hydrogen sulfide and ammonia mixtures

The positive ion-molecule reactions in the mixtures of hydrogen sulfide and ammonia have been examined by means of quadrupole mass spectrometer with high-pressure ion source. The concentration of hydrogen sulfide in mixtures ranged from 10% to 90% with 10% increment. Mainly observed primary ions: NH₂⁺ (m/q=16), NH₃⁺ (m/q=17), S⁺ (m/q=32) and H₂S⁺ (m/q=34) were formed as the result of ionization and dissociative ionization by electrons with energy of 300 eV. For each mixture, major bimolecular ion-molecule reactions have been identified at total pressure from 0.5 to 33.3 Pa. The main secondary ions: NH₄⁺ (m/q=18), H₃S⁺ (m/q=35) and NH₃S⁺ (m/q=49) were observed.Relative intensities of ion currents for observed ions were determined as a function of total gas pressure inside ion source collision chamber, repeller potential and concentration of hydrogen sulfide in the mixture.     

Low-temperature synthesis of uniform Sb2S3 nanorods and its visible-light-driven photocatalytic activities

Antimony sulfide (Sb₂S₃) nanorods with uniform size were prepared by the decomposition of Sb(C₇H₇OCSS)₃ in N,N-dimethylformamide solution at 80 °C. The as-prepared Sb₂S₃ was orthorhombic phase and consisted of nanorods with the typical lengths in the range of 200–500 nm and the average diameter of ca. 30 nm. The photocatalytic experiment by degrading methyl orange in aqueous solution under visible light indicated that the activity of the dispersed Sb₂S₃ nanorods was better than that of Sb₂S₃ superstructures aggregated by nanorods.     

Synthesis and crystal structures of a new (2,3-(CH3)2C6H3NH3)H2XO4 (X=P,As)

The aim of encapsulation of 2,3-dimethylanilinium cation in (H₂XO₄)_n polymeric anion chains is to build acentric frameworks that are efficient for non-linear optical (NLO) applications. The synthesis and structures of two new inorganic–organic NLO crystals with general formula (2,3-(CH₃)₂C₆H₃NH₃)H₂XO₄ (X=P, As) are reported. The magnitude of their second harmonic generations (SHG) responses was found to be between the KDP and urea. They crystallize with monoclinic unit-cells and are isotopic. We have determined the structure of phosphoric salt. The following unit-cell parameters were found: a=8.866(3) Å, b=5.909(6) Å, c=10.644(5) Å, β=112.44(1)°, V=515.5(5) Å³ and D_X=1.412 g cm⁻³. The space group is P2₁ with Z=2. The structure was refined with R=0.041 (R_w=0.057) for 1652 reflections with I≥3σ(I). It exhibits infinite (H₂PO₄)_nⁿ⁻ chains. The organic groups (2,3-(CH₃)₂C₆H₃NH₃)⁺ are anchored between adjacent polyanions through multiple hydrogen bonds. Chemical preparation, crystal structure, calorimetric and spectroscopic investigation are described.     

Selective recognition of Pr3 + based on fluorescence enhancement sensor

(E)-2-(1-(4-hydroxy-2-oxo-2H-chromen-3-yl)ethylidene)hydrazinecarbothioamide (L) has been used to detect trace amounts of praseodymium ion in acetonitrile–water solution (MeCN/H₂O) by fluorescence spectroscopy. The fluorescent probe undergoes fluorescent emission intensity enhancement upon binding to Pr^3 + ions in MeCN/H₂O (9/1:v/v) solution. The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and Pr^3 +, which has been utilized as the basis for selective detection of Pr^3 +. The sensor can be applied to the quantification of praseodymium ion with a linear range of 1.6 × 10^? 7 to 1.0 × 10^? 5 M. The limit of detection was 8.3 × 10^? 8 M. The sensor exhibits high selectivity toward praseodymium ions in comparison with common metal ions. The proposed fluorescent sensor was successfully used for determination of Pr^3 + in water samples.     

Impact of Nd3+ ions on physical and optical properties of Lithium Magnesium Borate glass

Enhancing the up-conversion efficiency of borate glass via optimized doping of rare earth ions is an ever-ending quest in lasing glass. Neodymium (Nd³⁺) doped Lithium Magnesium Borate (LMB) glasses are prepared using the melt-quenching method. X-ray diffraction (XRD), Fourier transformed infrared (FTIR), UV–Vis–NIR absorption and Photoluminescence (PL) spectroscopic characterizations are made to examine the influence of Nd³⁺ concentration on physical properties and optical properties. Nd³⁺ contents dependent density, molar volume, refractive index, ion concentration, Polaron radius, inter nuclear distance, field strength, energy band gap and oscillator strength are calculated. XRD patterns confirm the amorphous nature of all glasses and the FTIR spectra reveal the presence of BO₃ and BO₄ functional groups. UV–Vis–IR spectra exhibit ten prominent bands centered at 871, 799, 741, 677, 625, 580, 522, 468, 426, 349 nm corresponding to the transitions from the ground state to ⁴F_3/2, (⁴F_5/2 + ²H_9/2), (⁴F_7/2 + ⁴S_3/2), ⁴F_9/2, ²H_11/2, (⁴G_5/2 + ²G_7/2), (²K_13/2 + ⁴G_7/2 + ⁴G_9/2), (²G_9/2 + ²D_3/2 + ²P_3/2), (²P_1/2 + ²D_5/2), (⁴D_3/2 + ⁴D_5/2) excited states, respectively. A hyper-sensitive transition related to (⁴G_5/2 + ²G_7/2) level is evidenced at 580 nm. The room temperature up-conversion emission spectra at 800 nm excitation displays three peaks centered at 660, 610 and 540 nm. Glass with 0.5 mol% of Nd³⁺ showing an emission enhancement by a factor to two is attributed to the energy transfer between Mg²⁺ and Nd³⁺ ions. Our results suggest that these glasses can be nominated for solid state lasers and other photonic devices.     

Preparation,crystal structure and characterization of α-NaSbP2S6 and β-NaSbP2S6 phases

The new phases α-NaSbP₂S₆ and β-NaSbP₂S₆ were synthesized by ceramic and reactive flux methods at 773 K. The structures of α-NaSbP₂S₆ and β-NaSbP₂S₆ were determined by the single-crystal X-ray diffraction technique. α-NaSbP₂S₆ crystallizes in the monoclinic space group P2₁/c with a = 11.231(2) Å, b = 7.2807(15) Å, c = 11.640(2) Å, β = 108.99(3)°, V = 900.0(3) Å³ and z = 4. β-NaSbP₂S₆ crystallizes in the monoclinic space group P2₁ with a = 6.6167(13) Å, b = 7.3993(15) Å, c = 9.895(2) Å, β = 92.12(3) °, V = 484.10(17) Å³ and z = 2.The α- and β-phases of NaSbP₂S₆ are closely related, the main difference lies in the stacking of the [Sb[P₂S₆]]_nⁿ⁻ layers. The structure of α-NaSbP₂S₆ consists of two condensed layers (MPS₃ type) to give an ABAB… sequence with Na⁺ cations located in the interlayer space. The packing of β-NaSbP₂S₆ is formed by monolayers of [Sb[P₂S₆]]_nⁿ⁻ stacked in an AA… fashion separated by a layer of Na⁺ cations. Both phases are derivates of the M¹⁺M³⁺P₂Q₆ family.The optical band gaps of α-NaSbP₂S₆ and β-NaSbP₂S₆ were determined by UV–vis diffuse reflectance measurements to be 2.17 and 2.25 eV, respectively.     

Crystal structure of a new organic dihydrogenomonophosphate (C6H8N3O)2(H2PO4)2

Chemical preparation, X-ray single-crystal, thermal behavior, and IR spectroscopy investigations are given for a new organic cation dihydrogenomonophosphate (C₆H₈N₃O)₂(H₂PO₄)₂ (denoted IAHP) in the solid state. This compound crystallizes in the orthorhombic space group P2₁2₁2₁. The unit cell dimensions are: a = 7.422(3) Å, b = 12.568(5) Å, c = 20.059(8) Å with V = 1871.1(13) Å³ and Z = 4. The structure has been solved using direct method and refined to a reliability R factor of 0.029. The atomic arrangement can be described as inorganic layers of H₂PO₄⁻ anions between which are located the organic groups (C₆H₈N₃O)⁺ through multiple hydrogen bonds.     

A Ho(III) potentiometric polymeric membrane sensor based on a new four dentate neutral ion carrier

In this research, we report a new Ho^3 +-PVC membrane electrode based on N-(4,5-dimethyl-2-(picolinamido)phenyl)picolinamide (H₂Me₂bpb) as a suitable ion carrier. Poly vinylchloride (PVC)-based membrane composed of H₂Me₂bpb with oleic acid (OA) as anionic additives, and o-nitrophenyloctyl ether (NPOE) as plasticized solvent mediator. The sensor exhibits a Nernstian slope of 20.1 ± 0.2 mV decade^? 1 over the concentration range of 1.0 × 10^? 6 to 1.0 × 1^? 2 mol L^? 1, and a detection limit of 5.0 × 10^? 7 mol L^? 1 of Ho^3 + ions. The potentiometric response of the sensor is independent of the solution pH in the range of 3.5–9.4. It has a very short response time, in the whole concentration range (< 10 s), and can be used for at least eight weeks. The proposed electrode shows a good selectivity towards Ho^3 + ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. To assess its analytical applicability the proposed Ho^3 + sensor was successfully applied as an indicator electrode in the titration of Ho^3 + ion solutions in certified reference materials, alloy samples and for the determination of the fluoride ion in two mouthwash preparations.     

New quaternary alkali metal,rare earth (3+) thiophosphate,K2SmP2S7 with both [P2S6]4− and [PS4]3− anions

A new quaternary alkali metal, rare earth thiophosphate was synthesized by the ceramic method and characterized by single crystal X-ray diffraction: K₂SmP₂S₇ crystallizes in the monoclinic space group C2 (no. 5) with the unit cell parameters a = 22.746(5) Å, b = 6.7362(13) Å, c = 8.9004(18) Å, β = 99.68(3)°, V = 1344.3(5) Å³ and Z = 2. The phase K₂SmP₂S₇ can be better described as K₄Sm₂[PS₄]₂[P₂S₆] because it contains in the crystal structure both discrete anions [PS₄]^3? and [P₂S₆]^4?. The crystal structure consists of infinite chains of ¹_∞[SmPS₄] that are linked together through the ethane-like [P₂S₆]^4? anions to form two-dimensional layers. The packing of K₂SmP₂S₇ is formed by layers of ²_∞[Sm₂[PS₄]₂[P₂S₆]]^4? separated by K⁺ cations. K₂SmP₂S₇ was characterized by Raman and Fourier transform infrared (FTIR) spectroscopy and SEM-EDX microprobe analyses. The optical band gap of K₂SmP₂S₇ was determined by UV–vis diffuse reflectance measurements to be 2.59 eV.     

Development of a conductive composite based on polythiophene/Y-zeolite and its response towards sulfide ions

A new potentiometric sensor electrode for sulfide based on conducting polymer films is introduced. A composite of polythiophene (PTP) with Y-zeolite was prepared via chemical oxidative polymerization of thiophene (TP) in presence of a dispersion of Y-zeolite (powder) in CHCl3 solvent using anhydrous FeCl3 oxidant. Formation of polythiophene and its subsequent SEM and TEM analysis revealed formation of composite particles with average diameter in the range of 0.3–0.35 μm. DC conductivity value of the PTP-Y-zeolite composite was in the order of 10? 2 S/cm, which was indeed high compared to that of PTP, produced under identical conditions as above without the presence of Y-zeolite. This composite as active component with graphite powder and binding liquid was mixed and then used for preparation of solid state electrodes. The working temperature range for this electrode is between 20 and 40 °C. The linear dynamic range is 1 × 10? 7 – 1 × 10? 4 M and measures total sulfide concentration over a range of pH from 5 to 9. The composite electrode showed high selectivity for sulfide in the presence of many common interfering anions (? log KS, IO3?Pot = 6.3, ? log KS, BrO3?Pot = 5.5, ? log KS, S2O32 ?Pot = 4.8).     

Characterization of mechanochemically synthesized MHSO4–H4SiW12O40 composites (M = K,NH4, Cs)

Anhydrous proton conductive MHSO₄–H₄SiW₁₂O₄₀ (MHS–STA) composites were successfully synthesized using mechanochemical treatment. 80MHS·20STA (mol%) composite, for example, showed very high anhydrous proton conductivity above 10^?3 S cm^?1 in a temperature range from 160 to 60 °C under ambient pressure. From the X-ray diffraction study, it was confirmed that the mechanochemical treatment induced chemical interactions via ion-exchange between M⁺ ion in MHS and H⁺ ion in STA. Furthermore, phase-transition of raw substances, such as melting, dehydration and superprotic phase-transition, was suppressed in mechanochemically synthesized MHS–STA composites, indicating that improvement of anhydrous proton conductivity for MHS–STA composites is caused by the changes in protic conduction behavior.     

Synthesis and crystal structure of tetramethylammonium fluoride octadecasil

Octadecasil, a clathrate-type inclusion compound, has been synthesized hydrothermally at 453 K with a gel having the composition 1.0SiO₂:0.53tetramethylammonium (TMA⁺):0.54fluoride:86H₂O. The crystal structure has been determined based on powder X-ray diffraction data taken at 298 K, and has been refined using Rietveld method. The result confirms the AST-type, all-silica framework model developed by Caullet et al. [P. Caullet, J.L. Guth, J. Hazm, J.M. Lamblin, H. Gies, Eur. J. Solid State Inorg. Chem. 28 (1991) 345]. Furthermore, by using a rigid body model the position and orientation of the occluded TMA⁺ cation in the rhombododecahedral [4⁶6¹²] cage can be determined; F⁻ anion has been located in the hexahedral [4⁶] cage. The unit cell parameters, in the tetragonal space group I4/m, have been refined as: a = b = 9.07 Å, c = 13.44 Å, cell volume = 1104.97 Å³. The refined unit cell composition is |[N(CH₃)₄⁺]_2.0F⁻_1.9|[Si₂₀O₄₀], i.e., both TMA⁺ and F⁻ ions possess near full occupancies, and compensate each other's electronic charges. The crystallization of the AST framework structure is the result of a cooperative structure-directing effect of both ions.     

High pressure mass-spectrometric investigations of ion–molecule reactions in propane and argon mixtures

Ion–molecule reactions initiated by electron impact in the propane–argon mixtures have been studied by a quadrupole mass spectrometer with a high pressure ion source. The total gas pressure of investigated mixtures was 1.33 Pa. The influence of repeller potential on the ion–molecule reactions has been studied. The repeller potential was changed in the range 2–12 V. Measurements were performed for different concentrations of propane in the mixture with argon (from 10% C₃H₈ + 90% Ar to 90% C₃H₈ + 10% Ar with 10% propane increments). The major ion–molecule reactions have been identified. The primary ions produced in the gas by the electrons with the energy of 300 eV and the secondary ones from the ion–molecule reactions were observed. Relative intensities for primary and secondary ions are presented as a function of potential of the repeller electrode and concentration of propane in the mixtures with argon.     

Lithium solubility limit in ZnGa2O4:Bi0.0013+,Li+ phosphor

The lithium solubility limit, photoluminescence (PL) and photoluminescence excitation (PLE) properties of lithium ion co-activated ZnGa₂O₄:Bi³⁺,Li⁺ phosphor have been investigated. A LiGaO₂ second phase began to appear from 3 mol% Li⁺ ion co-activated ZnGa₂O₄:Bi³⁺,Li⁺ phosphor. The enhanced brightness of blue (λ_ex = 254 nm) and white (λ_ex = 315 nm) colors of bismuth ions doped ZnGa₂O₄:Bi³⁺,Li⁺ phosphor was assigned to the formation of LiGaO₂. Bi³⁺ activated lithium zinc gallate phosphor showed a more enhanced PLE peak around 315 nm than that of lithium zinc gallate phosphor when λ_em = 520 nm. Thus, we observed that the PL intensity of ZnGa₂O₄:Bi³⁺,Li⁺ phosphor with λ_em = 520 nm was much greater than that of ZnGa₂O₄:Li⁺ phosphor. Also, ZnGa₂O₄:Bi³⁺,Li⁺ phosphor exhibited a shorter decay time than that of ZnGa₂O₄:Li⁺ phosphor by about a factor of about 2.     

Structural,thermal, spectroscopic and magnetic studies of the (C2N2H10)0.5[FexV1−x(HPO3)2] (x = 0.26, 0.52, 0.74) solid solution

The (C₂N₂H₁₀)_0.5[Fe_xV_1−x(HPO₃)₂] (x = 0.26, 0.52 0.74) compounds have been obtained by mild solvothermal conditions in the form of micro-crystalline powder with brown color. The crystal structures were refined by X-ray powder diffraction data using the Rietveld method. The compounds crystallize in the monoclinic system, space group P2/c with the unit-cell parameters, a = 9.262(5) Å, b = 8.823(5) Å, c = 9.714(6) Å, β = 120.84(3)°; a = 9.245(1) Å, b = 8.823(1) Å, c = 9.698(1)Å, β = 120.80(1)° and, a = 9.254(4)Å, b = 8.822(4)Å, c = 9.702(4)Å, β = 120.73(3)° for (C₂N₂H₁₀)_0.5[Fe_0.26V_0.74 (HPO₃)₂] (1), (C₂N₂H₁₀)_0.5[Fe_0.52V_0.48(HPO₃)₂] (2), and (C₂N₂H₁₀)_0.5[Fe_0.74V_0.26(HPO₃)₂] (3). The compounds show an open crystalline structure with three-dimensional character, whose formula for the anionic inorganic skeleton is [M(HPO₃)₂]²⁻. The inorganic framework is formed by [MO₆] octahedra inter-connected by phosphite groups. The structure of the compounds exhibits channels extended along the [1 0 0] and [0 0 1] directions and the ethylendiammonium cations are located inside these channels, linked through hydrogen bonds and ionic interactions. The infrared spectra show the bands corresponding to the stretching (P–H) vibration of the phosphite group and the band corresponding to the deformation mode of the ethylendiammonium cation, δ(NH₃⁺). The thermal and thermodiffractometric behavior show that the compounds are stable up to approximately 300 °C, at higher temperatures the decomposition of the crystal structure by calcination of the organic cation starts. The diffuse reflectance spectra show bands of the V³⁺ ion (d²), and a band of the Fe³⁺ ion (d⁵), in a slightly distorted octahedral symmetry. The values of the Dq and Racah parameters (B and C) have been calculated for the V(III) cation. Magnetic measurements were performed on a powdered sample from 5 to 300 K at magnetic fields 1000, 500 and 100 G, in the ZFC and FC modes. At the magnetic field of 1000 G antiferromagnetic interactions were observed, but at 100 G have been detected higher values of the χ_m in the FC mode than those observed in the ZFC one, indicating the existence of a dominant ferromagnetic component at low temperature. The magnetization measurements show hystheresis loops at 5 K, with values of the remanent magnetization and coercive field of 1.91 emu/mol and 23 Gauss for (1), 25 emu/mol and 300 Gauss for (2), and 3 emu/mol and 50 Gauss for the compound (3).     

Room temperature oxidative intercalation with chalcogen hydrides: Two-step method for the formation of alkali-metal chalcogenide arrays within layered perovskites

A two-step topochemical reaction strategy utilizing oxidative intercalation with gaseous chalcogen hydrides is presented. Initially, the Dion-Jacobson-type layered perovskite, RbLaNb₂O₇, is intercalated reductively with rubidium metal to make the Ruddlesden-Popper-type layered perovskite, Rb₂LaNb₂O₇. This compound is then reacted at room-temperature with in situ generated H₂S gas to create RbS layers within the perovskite host. Rietveld refinement of X-ray powder diffraction data (tetragonal, a = 3.8998(2) Å, c = 15.256(1) Å; space group P4/mmm) shows the compound to be isostructural with (Rb₂Cl)LaNb₂O₇ where the sulfide resides on a cubic interlayer site surrounded by rubidium ions. The mass increase seen on sulfur intercalation and the refined S site occupation factor (～0.8) of the product indicate a higher sulfur content than expected for S^2? alone. This combined with the Raman studies, which show evidence for an HS stretch, indicate that a significant fraction of the intercalated sulfide exists as hydrogen sulfide ion. Intercalation reactions with H₂Se_(g) were also carried out and appear to produce an isostructural selenide compound. The utilization of such gaseous hydride reagents could significantly expand multistep topochemistry to a larger number of intercalants.