Alkali halide surfaces: Adsorbate binding energies and structures at surface defects

1977 ◽  
Vol 66 (8) ◽  
pp. 3437-3447 ◽  
Author(s):  
Robert B. Bjorklund ◽  
Kenneth G. Spears
Keyword(s):  
Alkali Halide ◽  
Surface Defects ◽  
Binding Energies

Alkali halide surfaces: Measurements and modeling of adsorbate motions and reactions at surface defects

1977 ◽  
Vol 66 (8) ◽  
pp. 3426-3436 ◽  
Author(s):  
Robert B. Bjorklund ◽  
Joseph E. Lester ◽  
Kenneth G. Spears
Keyword(s):  
Alkali Halide ◽  
Surface Defects

Binding Energies of Alkali Halide Molecules

1961 ◽  
Vol 34 (6) ◽  
pp. 2069-2078 ◽  
Author(s):  
G. M. Rothberg
Keyword(s):  
Alkali Halide ◽  
Binding Energies

scholarly journals Erratum: Binding Energies of Alkali Halide Molecules

1961 ◽  
Vol 35 (3) ◽  
pp. 1137-1137
Author(s):  
G. M. Rothberg
Keyword(s):  
Alkali Halide ◽  
Binding Energies

scholarly journals Evaluation of usage-induced degradation of different endodontic file systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shekhar Bhatia ◽  
Venkatesh Nagendrababu ◽  
Ove A. Peters ◽  
Amr Fawzy ◽  
Umer Daood
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
File System ◽  
File Systems ◽  
Passive Layer ◽  
Binding Energies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After

AbstractTo evaluate structural profiles and mechanical behaviour of WaveOne Gold (WOG), Twisted File Adaptive (TFA) and XP-endo shaper (XPS) instruments after root canal preparation. Standardized in vitro shaping was performed in presence of 5.25% sodium hypochlorite. File morphology was analyzed using scanning electron microscopy; X-ray diffraction analysis was performed before and after use along with Raman spectroscopy. Nanoindentation was carried out to characterize surface topography. Ni2+ release was measured at 1, 3, 5 and 7 days. X-ray photoelectron spectroscopy (XPS) analysis was done before and after use. After allocating scan line shifts like in WOG, mechanical deformation was shown using first order polynomials. XPS file system showed minimal grooves on surface. SEM of WOG instrument showed scraping surface defects. Hardness varied from 8.11 ± 0.99 GPa in TFA system to 6.7 ± 1.27 GPa and 4.06 ± 4.1 GPa in XPS and WOG. Ni2+ concentration from WOG was 171.2 μg/L. Raman peak at 540–545 cm−1 is attributed to Cr2O3. High resolution of Ti 2p spectrum show distinctive peaks with binding energies dominating in WOG, XPS and TFA file system. XRD exhibited NiTi phases with diffraction peaks. WOG files showed more surface deterioration and less passive layer formation as compared to TFA and XPS systems.

scholarly journals A theoretical investigation of the geometries, vibrational frequencies, and binding energies of several alkali halide dimers

1993 ◽  
Vol 98 (3) ◽  
pp. 2182-2190 ◽  
Author(s):  
Robert P. Dickey ◽  
David Maurice ◽  
Robert J. Cave ◽  
Richard Mawhorter
Keyword(s):  
Theoretical Investigation ◽  
Alkali Halide ◽  
Vibrational Frequencies ◽  
Binding Energies

scholarly journals The Effect of Particle Size on the Optical and Electronic Properties of MgO Nanoparticles

2021 ◽  
Author(s):  
Martijn Zwijnenburg
Keyword(s):  
Particle Size ◽  
Surface Defects ◽  
Binding Energies ◽  
Edge States ◽  
Many Body ◽  
Mgo Nanoparticles ◽  
Optical Gap ◽  
Optical And Electronic Properties ◽  
Many Body Perturbation Theory ◽  
Effect Of Particle Size

The (band) edge states, fundamental gaps, optical gaps, exciton binding energies and UV-Vis spectra for a series of cuboidal nanoparticles of the prototypical oxide magnesium oxide (MgO), the largest of with has 216 atoms and edges of 1 nm, were predicted using many-body perturbation theory (ev<i>GW</i>-BSE). The evolution of the properties with particle size was explicitly studied. It was found that while the edge states and fundamental gap change with particle size, the optical gap remains essentially fixed for all but the smallest nanoparticles, in line with what was previously observed experimentally. The explanation for these observations is demonstrated to be that while the optical gap is associated with an exciton that is highly localised around the particle’s corner atoms, the edge states, while primarily localised on the magnesium corner atoms ­(electron) and oxygen corner atoms (hole), show significant delocalisation along the edges. The strong localisation of the exciton associated with the optical gap on the corner atoms is argued to also explain why the nanoparticles have a much smaller optical gaps and red-shifted spectra than bulk MgO. Finally, it is discussed how this non-quantum confinement behaviour, where the properties of the nanoparticles arise from surface defects rather than differences in localisation of edge or exciton states, appears typical of alkaline earth oxide nanoparticles, and that the true optical gap of bulk crystals of such materials is also probably the result of surface defects, even if unobservable experimentally. <br>

HIGH-SURFACE-AREA BIOCARBONS FOR REVERSIBLE ON-BOARD STORAGE OF NATURAL GAS AND HYDROGEN

2007 ◽  
Vol 1041 ◽  
Author(s):  
Peter Pfeifer ◽  
Jacob W. Burress ◽  
Mikael B. Wood ◽  
Cintia M. Lapilli ◽  
Sarah A. Barker ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Natural Gas ◽  
Kansas City ◽  
Spatial Organization ◽  
Surface Defects ◽  
High Surface ◽  
High Surface Area ◽  
Binding Energies ◽  
Nanoporous Carbons ◽  
Pore Size Distributions

AbstractAn overview is given of the development of advanced nanoporous carbons as storage ma-terials for natural gas (methane) and molecular hydrogen in on-board fuel tanks for next-generation clean automobiles. The carbons are produced in a multi-step process from corncob, have surface areas of up to 3500 m2/g, porosities of up to 0.8, and reversibly store, by physisorp-tion, record amounts of methane and hydrogen. Current best gravimetric and volumetric storage capacities are: 250 g CH4/kg carbon and 130 g CH4/liter carbon (199 V/V) at 35 bar and 293 K; and 80 g H2/kg carbon and 47 g H2/liter carbon at 47 bar and 77 K. This is the first time the DOE methane storage target of 180 V/V at 35 bar and ambient temperature has been reached and exceeded. The hydrogen values compare favorably with the 2010 DOE gravimetric and volu-metric targets for hydrogen. A prototype adsorbed natural gas (ANG) tank, loaded with carbon monoliths produced accordingly and currently undergoing a road test in Kansas City, is de-scribed. A preliminary analysis of the surface and pore structure is given that may shed light on the mechanisms leading to the extraordinary storage capacities of these materials. The analysis includes pore-size distributions from nitrogen adsorption isotherms; spatial organization of pores across the entire solid from small-angle x-ray scattering (SAXS); pore entrances from scanning electron microscopy (SEM) and transmission electron microscopy (TEM); H2 binding energies from temperature-programmed desorption (TPD); and analysis of surface defects from Raman spectra. For future materials, expected to have higher H2 binding energies via appropriate sur-face functionalization, preliminary projections of H2 storage capacities based on molecular dy-namics simulations of adsorption of H2 on graphite, are reported.

Defects in Crystals

1968 ◽  
Vol 26 ◽  
pp. 244-245
Author(s):  
Kenneth R. Lawless
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Surface Defects ◽  
Chemical Properties ◽  
Material Point ◽  
Crystal Defects ◽  
Defects In Crystals ◽  
Irradiation Effects ◽  
Normal Lattice ◽  
Line Defects

One of the most important applications of the electron microscope in recent years has been to the observation of defects in crystals. Replica techniques have been widely utilized for many years for the observation of surface defects, but more recently the most striking use of the electron microscope has been for the direct observation of internal defects in crystals, utilizing the transmission of electrons through thin samples.Defects in crystals may be classified basically as point defects, line defects, and planar defects, all of which play an important role in determining the physical or chemical properties of a material. Point defects are of two types, either vacancies where individual atoms are missing from lattice sites, or interstitials where an atom is situated in between normal lattice sites. The so-called point defects most commonly observed are actually aggregates of either vacancies or interstitials. Details of crystal defects of this type are considered in the special session on “Irradiation Effects in Materials” and will not be considered in detail in this session.

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