Predicted M(H2)12n+ (M = Ac, Th, Pa, U, La and n = 3, 4) complexes with twenty-four hydrogen atoms bound to the metal ion

2019 ◽  
Vol 55 (54) ◽  
pp. 7788-7791
Author(s):  
Meenakshi Joshi ◽  
Tapan K. Ghanty
Keyword(s):  
Metal Ion ◽  
Hydrogen Atoms ◽  
Actinide Ions

The first ever report showing that a maximum of 24 hydrogen atoms can directly bind to actinide ions in M–(η2-H2)12 complexes.

scholarly journals The electrolytic behaviour of thin films. Part I.—Hydrogen

1928 ◽  
Vol 120 (784) ◽  
pp. 59-79 ◽  
Keyword(s):  
Metal Ion ◽  
Active Material ◽  
Atomic Layer ◽  
Surface Concentration ◽  
Hydrogen Ion ◽  
Hydrogen Ions ◽  
Hydrogen Atoms ◽  
Hydrogen Electrode ◽  
Electrode Processes ◽  
A Value

Few investigations have been made on the electrolytic behaviour of very thin metallic films. Whilst the work of Oberbeck and of Pring reveals the fact that a deposited layer of metal but a few atoms thick will produce an electrode possessing all the electromotive properties of the massive metal, yet information is lacking on the alteration of the electromotive force as these layers are built up. It might be anticipated that the behaviour of the electrode during the deposition of the first few layers would lead to interesting results, giving some insight into the mechanism of electrode processes and the range of action of forces of adhesion. In view of this it was considered a matter of some interest to investigate how far it might be possible to obtain data on the electrode potential and the rate of solution of the deposited atoms during the building up of the first atomic layer. The problem of metal ion deposition from aqueous solutions is complicated by the presence of other ions, such as the hydrogen ion, which can deposit simultaneously with the metal and affect the potential. For this reason the deposition of the hydrogen ion was first studied. It is well known that, in general, in order to bring about the continuous deposition of hydrogen ions at a metallic cathode, the potential must be maintained at a value considerably more negative than that of a reversible hydrogen electrode in the same electrolyte. The view most generally accepted is that this overpotential is due to an accumulation of electromotively active material on the electrode, and it has been suggested by various workers that it may consist of metallic hydrides, hydrogen atoms or negative hydrogen ions. With the exception of a paper by Knobel, little work has been done in determining the actual quantity of hydrogen accumulated on the cathode during the establishment of overpotential. Knobel, making the assumptions that the material was atomic hydrogen, that the relation between the solution pressure of the hydrogen P and the surface concentration of atoms C H is given by the relation P = k C H m , and that the potential is related to the pressure by the Nernst expression, calculated this quantity from the rate of growth of overpotential and found that for most metals it was considerably less than an atomic layer.

scholarly journals Factors affecting the dissociation of metal ions from humic substances

2015 ◽  
Vol 79 (6) ◽  
pp. 1397-1405 ◽  
Author(s):  
Nick Bryan ◽  
Dominic Jones ◽  
Rose Keepax ◽  
Dean Farrelly ◽  
Liam Abrahamsen ◽  
...  
Keyword(s):  
Humic Acid ◽  
Metal Ions ◽  
Humic Substances ◽  
Rate Constants ◽  
Metal Ion ◽  
Dissociation Rate ◽  
Factors Affecting ◽  
Ion Concentrations ◽  
Dissociation Rate Constants ◽  
Actinide Ions

AbstractPreviously, it has been suggested that metal ions complexed to humic acid in the environment might show slower dissociation than those added to humic substances in the laboratory, which has serious implications for the transport of radionuclides in the environment. The dissociation of lanthanide and anthropogenic actinide ions from humic substance complexes has been studied as a function of humic concentration and metal ion:humic concentration ratio. The results suggest that the apparently slower kinetics observed for metal ions complexed in the environment are probably due to the large humic concentrations that are used in those studies. Further, there is no evidence that the dissociation rate constant varies at very low metal ion concentrations. Although humic samples size-fractionated by ultrafiltration showed that more metal may be bound non-exchangeably, there was no evidence for different rate constants. Ultrafiltration of Eu(III)/humic acid mixtures did show a shift in Eu from smaller to larger fractions over a period of two days. Therefore, the results suggest that dissociation rate constants determined in the laboratory at metal ion concentrations higher than those expected in the environment may be used in predicting radionuclide mobility, provided that the humic acid concentration is in the range expected at the site.

Charge Localisation in Heavy Alkali Metal Ion Complexes of 4,4'-Biphenyldicarboxylate

2016 ◽  
Vol 69 (5) ◽  
pp. 505 ◽  
Author(s):  
Jack Harrowfield ◽  
Pierre Thuéry
Keyword(s):  
Crystal Structure ◽  
Alkali Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Negative Charge ◽  
Hydrogen Atoms ◽  
Alkali Metal Ion ◽  
Tetrahedral Environment ◽  
Structure Determinations ◽  
Irregular Form

Crystal structure determinations on the isomorphous RbI and CsI complexes of 4,4′-biphenyldicarboxylate have shown the carboxylate entities to be coordinated in an unusual fashion where both oxygen atoms are in a tetrahedral environment indicative of negative charge localisation on each. The metal ions also show a highly irregular form of six-coordination, while the biphenyl units are planar, seemingly as a result of attractive interactions between the ortho hydrogen atoms.

Element Profiles of Surface Layers Created by Metal Ion Beam Assisted Deposition

1993 ◽  
Vol 316 ◽  
Author(s):  
Sergei M. Duvanov ◽  
Alexander P. Kobzev ◽  
Alexander M. Tolopa
Keyword(s):  
Metal Ion ◽  
Rutherford Backscattering Spectrometry ◽  
Ion Beam ◽  
Depth Profiling ◽  
Thin Layers ◽  
Glass Layer ◽  
Hydrogen Atoms ◽  
Surface Layers ◽  
Ion Beam Assisted Deposition ◽  
Metal Metal

ABSTRACTDepth profiles of elements in the surface layers of metals and metallized dielectrics were investigated by Rutherford Backscatteríng Spectrometry (RBS) (for the depth profiling of heavy elements), resonant elastic Backscattering Spectrometry (BS) of 4He+ and 1H+ (for the light elements depth profiling), Elastic Recoil Detection (ERD) of 1H+ (for depth profiling of hydrogen atoms), SIMS and AES techniques. The technological TAMEK source operated in the regime of ion beam assisted deposition (IBAD) of the metal ions (ion implantation at average beam energy ≤ 150 KeV and simultaneous deposition of the same ions at energy 100 eV) in pulse mode. Coatings were deposited on metal and glass samples at temperature of substrates T=100° C. In this report, we discuss the investigation results of samples modified by IBAD in technical vacuum produced by oil diffusion pumping. Phases like TiO, TiC, TiN, TiH are indicated in interface coating-substrate layers. The total thickness of mutually mixed metal-glass layer was found to be 400 nm and it was equal up to 3 µm for metal-metal layers. Cu/Al thin layers on a glass subsrate may be used as mirrors for powerful lasers with large (up to 5 J/cm2) energy contribution.

Remarks on the diffuse interstellar lines

1967 ◽  
Vol 31 ◽  
pp. 91-93 ◽  
Author(s):  
G. Herzberg
Keyword(s):  
Hydrogen Atoms ◽  
Interstellar Gas

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.

Aspects of high-resolution imaging with a scanning ion microprobe

1986 ◽  
Vol 44 ◽  
pp. 750-751
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
Y. L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Ion Mass Spectrometry ◽  
Chromatic Aberration ◽  
Ion Source ◽  
Ion Microprobe ◽  
Emission Pattern ◽  
Intrinsic Resolution ◽  
Resolution Imaging ◽  
20 Nm ◽  
Secondary Ion

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.

Scanning ion microscopy images

1987 ◽  
Vol 45 ◽  
pp. 180-181
Author(s):  
R. Levi-Setti ◽  
J.M. Chabala ◽  
Y.L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Emission ◽  
Scanning Method ◽  
Ion Channeling ◽  
Secondary Ions ◽  
High Resolution Images ◽  
Ion Microscopy ◽  
Z Contrast ◽  
Focused Beams ◽  
Microscopy Images

Finely focused beams extracted from liquid metal ion sources (LMIS) provide a wealth of secondary signals which can be exploited to create high resolution images by the scanning method. The images of scanning ion microscopy (SIM) encompass a variety of contrast mechanisms which we classify into two broad categories: a) Emission contrast and b) Analytical contrast.Emission contrast refers to those mechanisms inherent to the emission of secondaries by solids under ion bombardment. The contrast-carrying signals consist of ion-induced secondary electrons (ISE) and secondary ions (ISI). Both signals exhibit i) topographic emission contrast due to the existence of differential geometric emission and collection effects, ii) crystallographic emission contrast, due to primary ion channeling phenomena and differential oxidation of crystalline surfaces, iii) chemical emission or Z-contrast, related to the dependence of the secondary emission yields on the Z and surface chemical state of the target.

Sign in / Sign up

Export Citation Format

Share Document