Ionization Potential Of Metal Research Articles

Preparation, properties and applications of carbonaceous materials of B/C/N and C/N systems

Carbonaceous materials of the boron/carbon/nitrogen (B/C/N) system and carbon/nitrogen (C/N) system have been reviewed. A material with a composition BC 2 N made by CVD had the graphite-like layer structure. Sodium was intercalated into and de-intercalated out of BC 2 N by an electrochemical method, and the material can be used as an anode of sodium ion batteries. Magnesium was intercalated into BC 2 N by vapor phase reaction. The intercalations can be explained by a relation between the ionization potentials of metals and electron affinities of the host materials. C/N materials have a high hardness, are photoluminescent and exhibit reversible ion adsorption/desorption in solution. These properties depend on composition, chemical bonding and structure, and should be useful in wide fields. [TANSO 2013 (No. 258) 165–70.]

B/C/N系およびC/N系ヘテロ原子置換型炭素材料の作製，物性と応用

Carbonaceous materials of the boron/carbon/nitrogen (B/C/N) system and carbon/nitrogen (C/N) system have been reviewed. A material with a composition BC2N made by CVD had the graphite-like layer structure. Sodium was intercalated into and de-intercalated out of BC2N by an electrochemical method, and the material can be used as an anode of sodium ion batteries. Magnesium was intercalated into BC2N by vapor phase reaction. The intercalations can be explained by a relation between the ionization potentials of metals and electron affinities of the host materials. C/N materials have a high hardness, are photoluminescent and exhibit reversible ion adsorption/desorption in solution. These properties depend on composition, chemical bonding and structure, and should be useful in wide fields.

Delocalized electronic behavior observed in transition metal oxide clusters under strong-field excitation

Heterogeneously composed clusters are exposed to intensity resolved, 100 fs laser pulses to reveal the energy requirements for the production of the high charge states of both metal and nonmetal ions. The ionization and fragmentation of group V transition metal oxide clusters are here examined with laser intensities ranging nearly four orders in magnitude (∼3 × 10(11) W/cm(2) to ∼2 × 10(15) W/cm(2)) at 624 nm. The ionization potentials of the metal atoms are measured using both multiphoton ionization and tunneling ionization models. We demonstrate that the intensity selective scanning method can be utilized to measure the low ionization potentials of transition metals (∼7 eV). The high charge states demonstrate an enhancement in ionization that is three orders of magnitude lower in laser intensity than predicted for the atomic counterparts. Finally, the response from the various metals and the oxygen is compared to elucidate the mechanism of enhanced ionization that is observed. Specifically, the sequence of ion appearances demonstrates delocalized electron behavior over the entire cluster.

Infrared and Raman study of some isonicotinic acid metal(II) halide and tetracyanonickelate complexes

In this study the M(IN) 2Ni(CN) 4 [where M: Co, Ni, and Cd, and IN: isonicotinic acid, abbreviated to M–Ni–IN] tetracyanonickelate and some metal halide complexes with the following stoichiometries: M(IN) 6X 2 (M: Co; X: Cl and Br, and M: Ni; X: Cl, Br and I) and Hg(IN)X 2 (X: Cl, Br, and I) were synthesized for the first time. Certain chemical formulas were determined using elemental analysis results. The FT-IR and Raman spectra of the metal halide complexes were reported in the 4000–0 cm −1 region. The FT-IR spectra of tetracyanonickelate complexes were also reported in the 4000–400 cm −1 region. Vibrational assignments were given for all the observed bands. For a given series of isomorphous complexes, the sum of the difference between the values of the vibrational modes of the free isonicotinic acid and coordinated ligand was found to increase in the order of the second ionization potentials of metals. The frequency shifts were also found to be depending on the halogen. The proposed structure of tetracyanonickelate complexes consists of polymeric layers of |M–Ni(CN) 4| ∞ with the isonicotinic acid molecules bound directly to the metal atom.

Relativistic effects on the ground state properties of group 1 and group 11 cyanides estimated from quantum chemical calculations

All-electron scalar relativistic and nonrelativistic methods at various levels of the quantum chemical theory are employed to investigate spectroscopic constants for the cyanides of group 1 and group 11 metal atoms. The relativistic effect is small for the group 1 cyanides but much larger for the group 11 cyanides and increases as a function of the atomic charge. This can be explained in terms of the relativistic effects on the ionization potentials of metals and the atomic orbital contraction-dilations. The relativistic correction increases the covalent character of the bonding between the metal atom and the cyano radical in general. The spin-orbit effects on the spectroscopic properties are not so large except for the AuCN.

Synthesis and vibrational spectroscopic studies of isonicotinamide metal(II) halide complexes

Fourier transform infrared spectra (4000–200 cm −1) are reported for the metal (II) halide isonicotinamide complexes of the following stoichiometries: M(iso) 2X 2 [M Ni, Cu, Hg; X Cl; iso=isonicotinamide], M(iso) 2X 2 [M Ni, Cu; X Br], and Co(iso) 2I 2. Vibrational assignments are given for all the observed bands. The Raman spectra (4000–100 cm −1) are reported for the three of these complexes. Also, the ESR spectra of these complexes are given. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of the free isonicotinamide and complexed ligand was found to increase in the order of the second ionization potentials of metals. The frequency shifts are also found to depend on the halogen. The studied metal halide complexes were characterized by X-ray powder diffraction patterns and FTIR spectra. Certain chemical formulas were determined using elemental analysis results. Finally, the geometry optimization method was used to predict three dimensional molecular geometries of the complexes by using the HYPERCHEM 5.0 the level of the theory molecular mechanic.

Synthesis and vibrational spectra of metal halide complexes of 8-hydroxyquinoline in relation to their structures

Complexes of the type M(8-HOQ) 2X 2 (where M=Zn, Co; X=Cl, Br, I and M=Fe, X=Cl; 8-HOQ=(C 9H 7NO), 8-hydroxyquinoline) have been studied in the 4000–200 cm −1 region, and assignment of all the observed bands were made. The analysis of the vibrational spectra indicates that there are some structure-spectra correlations. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of uncoordinated 8-hydroxyquinoline and coordinated to metal ion 8-hydroxyquinoline was found to increase in the order of the second ionization potentials of metals. The frequency shifts were also found to depend on the halogen. Certain chemical formulas were determined using elemental analysis results.

Vibrational spectroscopic studies of metal(II) halide benzimidazole

Infrared spectra (4000–200 cm −1) are reported for metal halide(II) benzimidazole complexes of the following stoichiometries: M(benz)X 2 [M=Cd, Cu; X=Cl, Br; benz=benzimidazole], Co(benz) 2, and Co(benz) 2X 2 [X=Cl, Br, I]. Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure–spectra correlations. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of uncoordinated benzimidazole and coordinated to metal ion benzimidazole was found to increase in the order of the second ionization potentials of metals.

Synthesis, spectroscopic and structural studies on metal halide complexes of isonicotinamide

In this study, infrared (4000–200 cm −1) spectra are reported for the metal (II) halide isonicotinamide complexes of the following stoichiometries: M(iso) 2X 2 (M=Co, Mn, Zn; X=Cl, Br; iso=isonicotinamide) and M(iso)X 2 (M=Zn; Cu, X=I; M=Hg, X=Br). Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure–spectra correlations. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of uncoordinated isonicotinamide and coordinated to metal ion isonicotinamide was found to increase in the order of the second ionization potentials of metals. The frequency shifts were also found to depend on the halogen. The studied metal halide complexes were characterized by X-ray powder diffraction patterns and FT-IR spectra. Certain chemical formulas were determined using elemental analysis results.

Spectroscopic and theoretical investigations of vibrational frequencies in binary unsaturated transition-metal carbonyl cations, neutrals, and anions.

Spectroscopic and theoretical investigations of vibrational frequencies in binary unsaturated transition-metal carbonyl cations, neutrals, and anions.

Formation and stability of dodecahedral and fcc structures in metal—carbon clusters

The electronic structure and stability of the met—cars and the fcc TiC fragments has been investigated using the self-consistent molecular orbital calculations within the density functional theory. The fcc fragments are shown to be more stable than the dodecahedral met—cars. The formation of met—cars or the fcc clusters in beams is shown to be governed by the relative composition of Ti and C atoms. The stability of met—cars formed from elements across the transition metal series is proposed to be related to the transition metal ionization potential.

Some investigations on slow and fast arc voltage fluctuations for contact materials proceeding in various gases and direct current

Arc voltage fluctuations with control of the main experimental parameters are studied, taking into account the excitation and ionization potentials of both contact materials and gases. The actual parameters of the experiments are the contact material (Au, Ag, etc.), and the environmental (air, N/sub 2/, He, Ar, etc.), electrical (50 V, 0.1-3 A DC), and mechanical (opening speed 1 to 50 cm/s) parameters. The accurate voltage values of the consecutive arc plateaus included in arc phases are determined by statistical measurements and voltage histogram drawings. Each of these voltage plateaus is attributed to a specific combination of contact metal ionization potential and excitation metastable levels of the surrounding gases. It has been found that each phase can enclose more than one plateau, such as in helium where the two last plateaus occur in gaseous phase, while in ambient the metallic phase is constituted by the two earlier plateaus. According to the plateau attribution, arc phase duration could be the sum of the corresponding plateau durations. Moreover, during each plateau, fast potential fluctuations occur. The fast Fourier transform (FFT) analysis of arc voltage samples shows that the maximum of the spectrum of these fluctuations corresponds to a frequency which is as high as 60 MHz in the metallic phase and only a few megahertz in the gaseous phase.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

On the ionization potential of small metal and dielectric particles

The ionization potential of small metal and dielectric spheres is considered in different frameworks: classical, semiclassical, and quantum mechanical density functional approach. Classical calculations give conflicting results, and the generally accepted result for the ionization potential of a metal sphere of radius R: WI(R)=bulk work function+(3/8)q2/R is shown to be wrong, resulting from the classical image potential too close to the metal surface. Using appropriate cutoff to the image potential, the result WI(R)=bulk work function+(1/2)q2/R (previously obtained from solvation energy considerations) is recovered. Experimental results on relatively large particles are in agreement with the latter result. For very small clusters, deviations of experimental results from this classical behavior are shown by a density functional calculation to arise from quantum mechanical effects. These are first the spilloff of the electronic wave functions beyond the cluster edge and secondly from exchange and correlation contributions.

Electron transfer in groups of iron, cobalt, and copper triazene 1-oxides: Hammett correlation, ligand redistribution, and crystal field effects

The electron-transfer behavior of groups of pseudooctahedral ML3 and grossly planar Ca, complexes is reported (M Fe. Co; L triazene 1-oxide). A quasi-reversible proccess of type MLp+ e-⇌ML3(p=2,3) is identified with electrochemical techniques. The E°298 values (vs. SCE) fall in the following ranges: Fe, -O.76 to -0.14; Co, -0.56 to -0.08; Cu, -1.07 to -0.37. The values become more negative in the order CoL3, FeL3, and CuL2. For a given metal ion, E°298 shifts appreciably with ligand substituent. and a linear Hammett relationship is obeyed. The reaction constant is shown to decrease considerably when an extra bond intervenes between the metal and the substituent. Copper(II) complexes of bidentate ligands carrying an ortho substituent as well as the of a tetradentate ligand that enforce cis planar stereochemistry display abnormally negative shifts of E°298. When two iron(III) complexes are mixed, ligand scrambling occurs and the presence of mixed species is neatly established by cyclic voltammetry. The mixed complexes fit smoothly into the Hammett straight lines. The thermodynamic quantities controlling the trends of E°298 are considered. An attempt is made to assess the relative importance of spherical and nonspherical parts of the crystal fields. Among complexes of the same metal ion, it is possible to express the shift of E°298 in terms of the crystal field splitting parameter with a large proportionality constant. The copper(II) complexes show a ligand field band whose energy linearly correlates with E°298. The shift of E°298 between iron and cobalt couples is controlled by metal ionization potential and nearly equally important spherical and nonspherical crystal field contributions.

Mechanistic aspects of cathodic oxygen reduction

An investigation of cathodic oxygen reduction in pure and contaminated solutions using the ring-disc technique showed:o(1)On Pt and Ag under clean conditions the four-electron reduction of O2 is operative, only small amounts of H2O2 are produced. In contaminated solution, a decrease of the catalytically active surface of Pt is observed, but on Ag the H2O2 formation significantly increases.(2)The two-electron reduction of O2 to H2O2 takes place only on Au and C. On Pt and Ag under clean conditions the four-electron reduction of O2 is operative, only small amounts of H2O2 are produced. In contaminated solution, a decrease of the catalytically active surface of Pt is observed, but on Ag the H2O2 formation significantly increases. The two-electron reduction of O2 to H2O2 takes place only on Au and C. The results are interpreted considering different models of the O2 adsorption. The different behaviour of Au and Ag, both having almost identical electronic and crystallographic structures, is explained on the basis of simple MO calculations. An influence of the metal ionization potential on the type of the reaction is postulated which might be generalized for sp-materials.

Mechanistic aspects of cathodic oxygen reduction

An investigation of cathodic oxygen reduction in pure and contaminated solutions using the ring-disc technique showed: o (1) On Pt and Ag under clean conditions the four-electron reduction of O 2 is operative, only small amounts of H 2O 2 are produced. In contaminated solution, a decrease of the catalytically active surface of Pt is observed, but on Ag the H 2O 2 formation significantly increases. (2) The two-electron reduction of O 2 to H 2O 2 takes place only on Au and C. The results are interpreted considering different models of the O 2 adsorption. The different behaviour of Au and Ag, both having almost identical electronic and crystallographic structures, is explained on the basis of simple MO calculations. An influence of the metal ionization potential on the type of the reaction is postulated which might be generalized for sp-materials.

Explosive Sensitivity of Cobalt Ammine Azides

THE correlation of the explosive sensitivity of simple metal azides with the metal's ionization potential has been related to the control of the azide's electrons by the metal and a consequent influence on the activation energy of the decomposition reaction1. Gray has stressed the importance of both kinetic and thermodynamic factors in the problem of sensitivity, and pointed out that, in addition to influencing the activation energy, the ionization potential is a major factor in determining the heat of formation of simple metal azides2. Thus a correlation with sensitivity may be predicted on both kinetic and thermodynamic grounds and no simple indication of the importance of electron control is possible.