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1.
《Spectrochimica Acta Part B: Atomic Spectroscopy》1987,42(3):459-465
The relationship between atomisation and ionisation for Si, Ge and Sn in fuel-rich C2H2 and H2 flames has been studied by means of flame ionisation mass spectroscopy, thermochemical calculation of burnt gas equilibrium composition, and computer simulation of chemical ionisation kinetics. The mass spectra obtained from C2H2/Ar/O2 flames are similar to those from H2 diffusion flames: Sn yields Sn+ and SnOH+, Ge and Si yield GeOH+ and SIO+. These similarities are in contrast to the substantial differences in calculated atomisation found between the C2H2 and H2 flames. The discrepancies between atomisation and ionisation are reconciled by a chemical ionisation mechanism in which the ions SiH+, GeH+ and SnH+ are important intermediates. The ratios of atomic ions to protonated monoxides, M+:MOH+ are determined by the thermochemistry for the reaction, MOH+ + H ⇌ M+ + H2O. 相似文献
2.
Peng Liu Jianqiang Liu Dongju Zhang Changqiao Zhang 《International journal of quantum chemistry》2010,110(9):1583-1593
A very recent laser ablation‐molecular beam experiment shows that an Al+ ion can react with a single methylamine (MA, CH3NH2) or dimethylamine (DMA, (CH3)2NH) molecule to form a 1:1 ion–molecule complex Al+[CH3NH2] or Al+[(CH3)2NH)], whereas a dehydrogenated complex ion Cu+[CH3N] or Cu+[C2H5N] is detected, respectively, in the similar reaction for a Cu+ ion. Here, we show a comparative density functional theory study for the reactivities of the Al+ and Cu+ ions toward MA and DMA to reveal the intrinsic mechanism. It is found that the interactions of the Al+ ion with MA and DMA are mostly electrostatic, leading to the direct ion–molecule complexes, Al+? NH2CH3 and Al+? NH( CH3)2, in contrast to the non‐negligible covalent character in the corresponding Cu+‐containing complexes, Cu+? NH2CH3 and Cu+? NH( CH3)2. The general dehydrogenation mechanism for MA and DMA promoted by the Cu+ ion has been shown, and the preponderant structures contributing to the mass spectra of the product ions Cu+[CH3N] and Cu+[C2H5N] are rationalized as Cu+? NHCH2 and Cu+? N( CH2)( CH3). The presumed dehydrogenation reactions are also discussed for the Al+‐containing systems. However, the involved barriers are found to be too high to be overcome at low energy conditions. These results have rationalized all the experimental observations well. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
3.
Open-shell single-determinantal calculations are reported here for the molecular species H2, Li2+, N2, O2 (triplet), O22?;, O2?, O22+, O2+, and F2; corresponding closed-shell calculations are reported for the species H2, N2, O2 (singlet), O22?, O22+, and F2. The floating spherical Gaussian orbital (FSGO ) method was employed. The calculated trend in bond lengths of isonucleic diatomic molecules is in agreement with experiment. For heteronucleic diatomic molecules, however, the experimental trend in bond lengths is not obtained; in this connection, the effect of lone pairs on bond length is discussed. The dissociation energies of H2 and Li2+ are evaluated. The energy gap between the triplet and singlet states of the oxygen molecule is calculated to be 8.96 eV compared to the experimental value of 4.54 eV. 相似文献
4.
R. Barbieri N. Bertazzi C. Tomarchio R.H. Herber 《Journal of organometallic chemistry》1975,84(1):39-46
Tetraphenylarsonium and tetramethylammonium salts of the complex anions Ph3Sn(N3)?2, Ph3Sn(N3)(NCS)?, Me2Sn(N3)2?4 and Ph2Sn(N3)2(NCS)2?2 have been synthesized, and the solid state configuration of the complex anions has been studied by Mössbauer and vibrational spectroscopies. Trigonal bipyramidal structures are advanced for the Ph3SnIV derivatives, with equatorial SnC3 and apical pseudohalide ligands, while the R2SnIV compounds are assumed to be trans-octahedral species. The NCS? ligands are observed to be N-bonded to SnIV. Conductance and PMR (for the Me2SnIV compound) data suggest the presence of the complex anions also in solution phases. 相似文献
5.
Hamid Berriche 《International journal of quantum chemistry》2013,113(21):2405-2412
The potential energy curves of 26 electronic states of 2Σ+g, u, 2Πg, u, and 2Δg, u symmetries of the alkali dimer Na2+, dissociating up to Na(4d) + Na+, are investigated using an ab initio approach involving a nonempirical pseudopotential for the Na+(1s22s22p6) core and core‐valence correlation corrections. Furthermore, the transition dipole functions between many electronic states and vibrational energy spacings are presented. The spectroscopic constants of these electronic states are extracted and compared with the available theoretical and experimental results. A very good agreement is observed, especially, for the ground and the first excited states. However, the comparison between our study and the model potential (MP) calculations (Magnier and Masnnou‐Seeuws Mol. Phys. 1996, 89, 711) for several states has shown a clear disagreement. The MP well depths of the 3‐42Σ+g, 12Πg, 3‐42Πg, and 22Πu electronic states are largely underestimated. In addition, the 5‐72Σ+g, 3‐72Σ+u, 22Πg, 42Πg, and 1‐22Δu MP electronic states are repulsive, although in this work, they are attractive with potential well depths of some hundreds of cm?1. The data presented in this study are very useful for studies on ion–atom interaction and cold collision in the presence of electromagnetic fields. © 2013 Wiley Periodicals, Inc. 相似文献
6.
Dr. Chao Xu Dr. Guoxin Tian Dr. Simon J. Teat Dr. Guokui Liu Dr. Linfeng Rao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16690-16698
The complexation of NpO22+ and PuO22+ with dipicolinic acid (DPA) has been investigated in 0.1 M NaClO4 by spectrophotometry, microcalorimetry, and single crystal diffractometry. Formation of 1:1 and 1:2 (metal/ligand molar ratio) complexes of DPA with NpO22+ and PuO22+ were identified and the thermodynamic parameters were determined and compared with those of UO22+. All three hexavalent actinyl cations form strong 1:1 DPA complexes with slightly decreasing but comparable stability constants from UO22+ to PuO22+, whereas the stability constants of the 1:2 complexes (log β2) decrease substantially along the series (16.3 for UO2L22?, 15.17 for NpO2L22?, and 14.17 for PuO2L22? at 25 °C). The enthalpies of complexation for the 1:2 complexes become less exothermic from UO2L22? (?28.9 kJ mol?1), through NpO2L22? (?27.2 kJ mol?1), and to PuO2L22? (?22.7 kJ mol?1). The trends in the thermodynamic parameters are discussed in terms of the effective charge of the cations and the steric constraints in the structures of the complexes. In addition, the features of the absorption spectra, including the wavelength and intensity of the absorption bands, are related to the perturbation of the ligand field and the symmetry of the actinyl complexes. 相似文献
7.
《Journal of Inorganic and Nuclear Chemistry》1976,28(1):107-112
Detailed measurements on the kinetics and stiochiometry of the oxidation of hydrogen peroxide by aquosilver(II) ions are reported. Two AgaqII ions are consumed for each H2O2 which disappears, and for [H2O2]>[AgII] the reaction is first order in AgaqII and zero order in H2O2 with the rate independent of acidity in the range 2·0–4·8 M HClO4. The activation energy for the decomposition of the AgIIH2O2 complex ∼zero, similar to the oxidations of H2O2 by CeaqIV and MnaqIII. The contrasting orders in the oxidative reactivity towards H2O2 and in the redox potentials of the transition metal cations are discussed. It is suggested that, whereas AgaqII, CeaqIV, MnaqIII and FeaqIII oxidise H2O2 in one-electron transfers involving monomeric cations, the oxidation of H2O2 by CoaqIII may involve a two-electron step with dimeric CoIII. 相似文献
8.
Enrique Poulain Alberto Rubio‐Ponce Victor Hugo Uc Virineya Bertin Oscar Olvera‐Neria 《International journal of quantum chemistry》2013,113(13):1794-1802
Nitrous oxide (N2O) is an intermediate compound formed during catalysis occurring in automobile exhaust pipes. In this work, the N2O capture and activation by Pt and Pd atoms in the ground and excited states of many multiplicities are studied. Pt and Pd + N2O reactions are studied at multireference second‐order perturbation level of theory using Cs symmetry. The PtN2O (1A′, 5A′, and 5A″) species are spontaneously created from excited states. Only the 5A′ and 5A″ states exhibit N2O activation reaction paths when N2O approaches Pt end‐on by the N or O atoms side or side‐on yielding NO or N2 as products, respectively. Pt+ cations ground and excited states, capture N2O, although only Pt+ (6A′ and 6A″) states show N2O activation yielding O and N2 as products. In the Pd atom case, PdN2O (1A′ and 5A″) species are also spontaneously created from excited states. The 5A″ state exhibits N2O activation yielding N2 + O as products. Pd+ cations in both ground and excited states capture N2O; however, only the [PdN2O]+ (4A′, 4A″, 6A′, and 6A″) states in side‐on approaches and (6A′) in end‐on approach activate the N2O and yield the N2 bounded to the metal and O as product. The results obtained in this work are discussed and compared with previous calculations of Rh and Au atoms. The reaction paths show a metal–gas dative covalent bonding character. Löwdin charge population analyses for Pt and Pd active states show a binding done through charge donation and retrodonation between the metals and N2O. © 2013 Wiley Periodicals, Inc. 相似文献
9.
method has been developed for the selective photometric redox determination of periodate and iodate ions in bottled drinking water based on redox reactions of analytes with Methylene Blue with different duration of processes, products of which form the analytical signal. The limits of detection for periodate and iodate ions are 0.5 and 0.2 µg/L, respectively. The allowable weight ratios for concomitant ions for (at the analyte concentration 2 µg/L) are as follows: I–, Br–, IO3–, BrO3–, ClO–, CIO–, CIO2–, CIO3– and CIO4–(1: 100); and for IO3– (1 µg/L) are: BrO3–2–, NO (1: 60), CIO–, CIO2–, (1: 100), and I–, Br–, IO4–, CIO3–, and CIO4– (1: 200). The HCIO3–, Cl–, and SO42- anions and Ca2+, Mg2+, Na+, K2+, and NH4+ cations are macrocomponents of drinking water and at total concentrations up to 10 g/L do not affect the results of analysis. In the concentration range 1–10 µg/L of IO4– andIO3–, the total error of determination is 5–7%. 相似文献
10.
《Chemical physics》1987,114(3):305-320
Potential energy (PE) curves for the Rydberg states of F2, and for the ground and lowest two electronic states each of symmetry 2Πg,u, 2Δg,u and 2Σ±g,u of F+2, have been obtained using modest-sized configuration-interaction calculations. These PE curves have been used to calculate spectroscopic constants for the electronic states and the results agree reasonably well with the limited experimental and theoretical results previously reported. The theoretical PE curves for the Rydberg states of F2 are found to be strongly perturbed by valence-Rydberg-ionic interactions and these perturbations appear to be responsible for certain features in recently reported electron energy-loss spectra in F2. The corresponding electronic wavefunctions have been used to calculate the electronic transition moment, as a function of the internuclear distance, for dipole-allowed transitions between the lowest excited electron state of each symmetry and the appropriate ground electronic state. The radiative emission probabilities, natural lifetimes, and absorption oscillator strengths, for each band system, are also reported here. The predicted lifetimes for vibrational levels of the A 2Πu of electronic state in F+2 vary from 1.3–1.5 μs and agree reasonably well with the single available set of measurements. The predicted radiative lifetimes for the higher electronic states of F+2 are substantially longer and fall into the range 5–100 ms. 相似文献
11.
Mobilities of H+ and H? in He and in H2, and of H+2 and H+3 in He, are calculated from ion-neutral potentials derived from theory and ion-beam scattering. Agreement with experiment is reasonable except for H? in H2 and H+2 in He, which present unexplained puzzles. 相似文献
12.
The dissociative photoionization of molecular‐beam cooled CH2CO in a region of ?10–20 eV was investigated with photoionization mass spectrometry using a synchrotron radiation as the light source. Photoionization efficiency curves of CH2CO+ and of observed fragment ions CH2+, CHCO+, HCO+, C2O+, CO+, and C2H2+ were measured to determine their appearance energies. Relative branching ratios as a function of photon energy were determined. Energies for formation of these observed fragment ions and their neutral counterparts upon ionization of CH2CO are computed with the Gaussian‐3 method. Dissociative photoionization channels associated with six observed fragment ions are proposed based on comparison of determined appearance energies and predicted energies. The principal dissociative processes are direct breaking of C=C and C‐H bonds to form CH2+ + CO and CHCO+ + H, respectively; at greater energies, dissociation involving H migration takes place. 相似文献
13.
14.
Accurate nonadiabatic lower and upper bounds for groundstate energies of H
2
+
and D
2
+
are calculated with the linearized method of variance minimization. The results in a.u. are –0.597139063<E
0(H
2
+
)<–0.597138994 –0.598788775<E
0(D
2
+
)<–0.598778738 i.e. the values are determined with an absolute error smaller than 0.02 cm–1 for H
2
+
and 0.01 cm–1 for D
2
+
. 相似文献
15.
Two oxidation waves are observed at mercury electrodes for tetraphenyllead in dichloromethane. The mechanisms of the oxidation processes have been investigated by dc and differential pulse polarography. The first wave is a broad two-electron step and represents the summation of a number of processes related to mercury exchange and halide abstraction. The exchange reactions are as follows: 2 Φ4Pb + Hg→2Φ3Pb+ + Φ2Hg+2e? 2 Φ3Pb+ + Hg→2Φ2Pb2+ + Φ2Hg+2e? Dichloroethane and HgCl2 are identified as products of controlled potential electrolysis experiments as well as Φ2Hg and Φ2PbCl2 implying that the coordinatively unsaturated Φ3Pb+ and/or Φ2Pb2+ react with the solvent dichloromethane and abstract chloride. The second oxidation process is the two electron step. Φ2Hg+Hg→2 ΦHg+ + 2e?Tetraalkyllead compounds (tetramethyl, tetraethyl, tetrabutyl) also give rise to related electrode processes at mercury electrodes and polarographic techniques may form the basis of a method for their analytical determination if separated chromatographically prior to detection. 相似文献
16.
《Chemical physics letters》1987,141(3):166-174
There is much experimental interest in weakly bound cluster ions. Here we present the first ab initio study of ArH3+, ArD3+, ArHD2+, and ArDH2+. Structures and harmonic frequencies are reported at the MP2 level of theory using large basis sets. SCF anharmonic corrections are also reported. CISD and CPF calculations with the smallest of the basis sets used in this study are used to refine further the MP2 harmonic frequencies. The most intense infrared vibrations are the ν2 (a1, H3+ bend) and ν3 (a1, intermolecular Ar…H stretch), for which our best predictions of the fundamental vibrations obtained by combining MP2 harmonic and SCF anharmonic corrections are 1819 and 395 cm−1. 相似文献
17.
A multi-responsive Cd metal–organic framework {[Cd (ttpe)(H2O)(ip)]•4H2O•DMAC}n ( 1•4H 2 O•DMAC ) was synthesized using hydrothermal method (ttpe = 1,1,2,2-tetra(4-(1H-1,2,4-triazol-1-yl)phenyl)ethylene, ip = isophthalate, DMAC = N,N-dimethylacetamide), and characterized. 1 exhibits a 2D (4,4) network. The luminescent sensing experimrnts showed that 1•4H 2 O•DMAC as a new MOF luminescent sensor can detect Cr2O72−, CrO42−, MnO4−, Cu2+, Ag+ and Fe3+ in aqueous solution with simultaneously high efficiency and high sensitivity. The quenching constants Ksv for Cr2O72−, CrO42−, MnO4−, Cu2+, Ag+ and Fe3+ are 4.231 × 104 M−1, 2.471 × 104 M−1, 6.459 × 103 M−1, 7.617 × 103 M−1, 1.563 × 104 M−1 and 3.574 × 104 M−1, respectively. The detection limits are 0.094 μM for Cr2O72−, 0.108 μM for CrO42 − , 0.346 μM for MnO4−, 0.302 μM for Cu2+, 0.221 μM for Ag + , and 0.100 μM for Fe3+. 1•4H 2 O•DMAC exhibits high photocatalytic efficiency for degradation of methylene blue under visible light irradiation. 相似文献
18.
Molecular structures and energies have been calculated in the MNDO approximation, for P4S3 and its molecular ion P4S3+, and for the mass spectral fragment pairs: (P3S3+ + P), (P3S2+ + PS), (P3S+ + PS2), (P2S3+ + P2), (P2S2+ + P2S), (P2S+ + P2S2), (P2S2), PS3+ + P3), (PS2+ + P3S), (PS+ + P3S2), and (PS+ + P2S + PS). Three distinct energy minima were found for each of P2S2+ and P2S2, and two minima for each of P2S+, P2S, PS3+, PS3+, PS2+, PS2, P3+ and P3. The fragments arising from P4 and P4+ were also investigated. The structures are discussed in terms of the Jahn—Teller effect, whose predictions are fulfilled without exception. 相似文献
19.
Pierre D. Harvey 《Macromolecular Symposia》2004,209(1):67-80
This paper describes how to determine molecular weights of coordination and organometallic polymers (or rather oligomers) in solution using spin-lattice relaxation time (T1) and Nuclear Overhauser Enhancement constant (ηNOE) measurements. The methodology is explained using simple organometallic-complexes such as M(CN-t-Bu)4+ complexes (M = Cu, Ag). Very good results are obtained for oligomers that exhibit a rigid structure. Conversely, very poor results are extracted when the materials show flexible chains in the backbone. The typical examples for rigid and flexible oligomers are the {Ag(dmb)2+}n (dmb = 1,8-diisocyano-p-menthane), and {Pd2(dmb)2(diphos)2+}n (diphos = dppa, dppb, dpppent, and dpph) as well as {Pd2(diphos)2(dmb)2+}n (diphos = dppe, dppr, and dppp R ; R = O(CH2)2O-naphthyl), respectively. 相似文献
20.
Diffusion and Ion Association in Concentrated Solutions of Aqueous Lithium, Sodium, and Potassium Sulfates 总被引:1,自引:0,他引:1
Taylor dispersion is used to measure mutual diffusion coefficients for aqueous Li2SO4 solutions at concentrations from 0.09 to 2.62 mol-dm-3 at 25°C. The Li2SO4 results and previously reported diffusion coefficients for aqueous Na2SO4 and K2SO4 are compared with predictions made by treating the limiting electrolyte diffusion coefficients as reference values and applying corrections for nonideal solution behavior, ionic hydration, and viscosity changes as the concentration is raised. Good agreement is obtained if the M+ + SO 4 2- ? MSO 4 - (M = Li, Na, K) association equilibria are included in the analysis. Extents of formation of the MSO 4 - ion pairs are evaluated by fitting Pitzer's mixed electrolyte equations for aqueous M+–MSO 4 - –SO 4 2- ions to osmotic coefficient data. Diffusion coefficients for hypothetical solutions of the completely dissociated M2SO4 electrolytes are calculated to illustrate the effects of ion association on diffusion. Association of the M+ and SO 4 2- ions increases the overall mobility and thermodynamic driving forces for their diffusion. 相似文献