Erratum: “Formation, trapping, and ejection of radiolytic O2 from ion-irradiated water ice studied by sputter depth profiling” [J. Chem. Phys. 130, 134704 (2009)]

2011 ◽  
Vol 134 (16) ◽  
pp. 169902
Author(s):  
B. D. Teolis ◽  
J. Shi ◽  
R. A. Baragiola
Keyword(s):  
Depth Profiling ◽  
Chem Phys ◽  
Water Ice

Publisher's Note: “Water formation through O2 + D pathway on cold silicate and amorphous water ice surfaces of interstellar interest” [J. Chem. Phys. 137, 234706 (2012)]

2013 ◽  
Vol 138 (7) ◽  
pp. 079902
Author(s):  
H. Chaabouni ◽  
M. Minissale ◽  
G. Manicò ◽  
E. Congiu ◽  
J. A. Noble ◽  
...  
Keyword(s):  
Chem Phys ◽  
Water Ice ◽  
Water Formation ◽  
Ice Surfaces

Preferential Sputtering of Ni3Al Single Crystals Studied Using Atom-Probe Field-Ion Microscopy and XPS

1981 ◽  
Vol 39 ◽  
pp. 16-17
Author(s):  
M.P. Thomas ◽  
A.R. Waugh ◽  
M.J. Southon ◽  
Brian Ralph
Keyword(s):  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Atom Probe ◽  
Probe Field ◽  
Preferential Sputtering ◽  
Argon Ion Bombardment ◽  
Argon Ion

It is well known that ion-induced sputtering from numerous multicomponent targets results in marked changes in surface composition (1). Preferential removal of one component results in surface enrichment in the less easily removed species. In this investigation, a time-of-flight atom-probe field-ion microscope A.P. together with X-ray photoelectron spectroscopy XPS have been used to monitor alterations in surface composition of Ni3Al single crystals under argon ion bombardment. The A.P. has been chosen for this investigation because of its ability using field evaporation to depth profile through a sputtered surface without the need for further ion sputtering. Incident ion energy and ion dose have been selected to reflect conditions widely used in surface analytical techniques for cleaning and depth-profiling of samples, typically 3keV and 1018 - 1020 ion m-2.

Atomic force microscopy (AFM) of the topography of silicon surfaces exposed to ion beams

1992 ◽  
Vol 50 (2) ◽  
pp. 1132-1133
Author(s):  
Mark Denker ◽  
Jennifer Wall ◽  
Mark Ray ◽  
Richard Linton
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Incidence Angle ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Ion Beams ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Trace Impurities ◽  
Energy Dose

Reactive ion beams such as O2+ and Cs+ are used in Secondary Ion Mass Spectrometry (SIMS) to analyze solids for trace impurities. Primary beam properties such as energy, dose, and incidence angle can be systematically varied to optimize depth resolution versus sensitivity tradeoffs for a given SIMS depth profiling application. However, it is generally observed that the sputtering process causes surface roughening, typically represented by nanometer-sized features such as cones, pits, pyramids, and ripples. A roughened surface will degrade the depth resolution of the SIMS data. The purpose of this study is to examine the relationship of the roughness of the surface to the primary ion beam energy, dose, and incidence angle. AFM offers the ability to quantitatively probe this surface roughness. For the initial investigations, the sample chosen was <100> silicon, and the ion beam was O2+.Work to date by other researchers typically employed Scanning Tunneling Microscopy (STM) to probe the surface topography.

Wordly Corrasions: Philology and Narrative inWorstward Ho

2017 ◽  
Vol 26 (1) ◽  
pp. 53-68
Author(s):  
Mark Byron
Keyword(s):  
First Principles ◽  
Alexander Pope ◽  
Literary Texts ◽  
Water Ice ◽  
Primary Documents ◽  
Land Farming ◽  
King James Bible ◽  
A Site ◽  
Thomas Browne ◽  
Geological Formations

Scholarly research over the last twenty years has marked a profound shift in the understanding of Beckett's sources, his methods of composition, and his attitudes towards citation and allusion in manuscript documents and published texts. Such landmark studies as James Knowlson's biography, Damned to Fame (1996), and John Pilling's edition of the Dream Notebook (1999), and the availability of primary documents such as Beckett's reading notes at Reading and Trinity libraries, opened the way for a generation of work rethinking Beckett's textual habitus. Given this profound reappraisal of Beckett's material processes of composition, this paper seeks to show that Beckett's late prose work, Worstward Ho, represents a profound mediation on writing, self-citation, and habits of allusion to the literary canon. In its epic gestures, it reorients the heavenly aspiration of Dante's Commedia earthwards, invoking instead the language of agriculture, geology and masonry in the process of creating and decreating its imaginative space. Beckett's earthy epic invokes and erodes the first principles of narrative by way of philology as well as by means of deft reference to literary texts and images preoccupied with land, farming, and geological formations. This process is described in the word corrasion, a geological term referring to the erosion of rock by various forms of water, ice, snow and moraine. Textual excursions into philology in Worstward Ho also unearth the strata comprising Beckett's corpus (in particular Imagination Dead Imagine, The Lost Ones, and Ill Seen Ill Said), as well as the rock or canon upon which his own literary production is built. A close reading of Worstward Ho turns up a number of shrewd allusions to the King James Bible and Thomas Browne, as one might expect, but also perhaps surprisingly sustained affinities with the literary sensibilities of Alexander Pope and the poetry of S. T. Coleridge. The more one digs, the more Beckett's ‘little epic’ seems to become one of earthworks, bits of pipe, and masonry, a site and record of literary sedimentation.

Injury-Risk Evaluation in Water Ice Climbing

2009 ◽  
Vol 13 (4) ◽  
pp. 210-218 ◽  
Author(s):  
Volker Schöffl ◽  
Isabelle Schöffl ◽  
Ulrich Schwarz ◽  
Friedrich Hennig ◽  
Thomas Küpper
Keyword(s):  
Risk Evaluation ◽  
Injury Risk ◽  
Water Ice

Computational Investigation of the Asymmetry in Photosynthetic Reaction Center Models from First Principles

2020 ◽  
Author(s):  
Denis Artiukhin ◽  
Patrick Eschenbach ◽  
Johannes Neugebauer
Keyword(s):  
Spin Density ◽  
Reaction Center ◽  
Density Functional ◽  
Photosynthetic Reaction Center ◽  
Chem Phys ◽  
Molecular Structures ◽  
Error Characteristic ◽  
Molecular Systems ◽  
Density Distributions ◽  
The Asymmetry

We present a computational analysis of the asymmetry in reaction center models of photosystem I, photosystem II, and bacteria from <i>Synechococcus elongatus</i>, <i>Thermococcus vulcanus</i>, and <i>Rhodobacter sphaeroides</i>, respectively. The recently developed FDE-diab methodology [J. Chem. Phys., 148 (2018), 214104] allowed us to effectively avoid the spin-density overdelocalization error characteristic for standard Kohn–Sham Density Functional Theory and to reliably calculate spin-density distributions and electronic couplings for a number of molecular systems ranging from dimeric models in vacuum to large protein including up to about 2000 atoms. The calculated spin densities showed a good agreement with available experimental results and were used to validate reaction center models reported in the literature. We demonstrated that the applied theoretical approach is very sensitive to changes in molecular structures and relative orientation of molecules. This makes FDE-diab a valuable tool for electronic structure calculations of large photosynthetic models effectively complementing the existing experimental techniques.

`Diet GMKTN55' Offers Accelerated Benchmarking Through a Representative Subset Approach

2018 ◽  
Author(s):  
Tim Gould
Keyword(s):  
Density Functional ◽  
Chem Phys ◽  
Comprehensive Analysis ◽  
Genetic Approach ◽  
Representative Subset ◽  
Phys Chem Chem Phys

The GMTKN55 benchmarking protocol introduced by [Goerigk et al., Phys. Chem. Chem. Phys., 2017, 19, 32184] allows comprehensive analysis and ranking of density functional approximations with diverse chemical behaviours. But this comprehensiveness comes at a cost: GMTKN55's 1500 benchmarking values require energies for around 2500 systems to be calculated, making it a costly exercise. This manuscript introduces three subsets of GMTKN55, consisting of 30, 100 and 150 systems, as `diet' substitutes for the full database. The subsets are chosen via a stochastic genetic approach, and consequently can reproduce key results of the full GMTKN55 database, including ranking of approximations.

Porous Aluminophosphates as Adsorbents for the Separation of CO2/CH4 and CH4/N2 Mixtures – a Monte Carlo Simulation Study

2018 ◽  
Author(s):  
Michael Fischer
Keyword(s):  
Monte Carlo ◽  
Landfill Gas ◽  
Experimental Studies ◽  
Chem Phys ◽  
Monte Carlo Simulation Study ◽  
Mixture Adsorption ◽  
Vacuum Swing Adsorption ◽  
Separation Of Co2 ◽  
Pressure Swing ◽  
Gcmc Simulations

<div>Aluminophosphates with zeolite-like topologies (AlPOs) have received considerable attention as potential adsorbents for use in the separation of methane-containing gas mixtures. Such separations, especially the removal of carbon dioxide and nitrogen from methane, are of great technological relevance in the context of the “upgrade” of natural gas, landfill gas, and biogas. While more than 50 zeolite frameworks have been synthesised in aluminophosphate composition or as heteroatom substituted AlPO derivatives, only a few of them have been characterised experimentally with regard to their adsorption and separation behaviour. In order to predict the potential of a variety of AlPO frameworks for applications in CO<sub>2</sub>/CH<sub>4</sub> and CH<sub>4</sub>/N<sub>2</sub> separations, atomistic grand-canonical Monte Carlo (GCMC) simulations were performed for 53 different structures. Building on previous work, which studied CO<sub>2</sub>/N<sub>2</sub> mixture adsorption in AlPOs (M. Fischer, <i>Phys. Chem. Chem. Phys.</i>, 2017, <b>19</b>, 22801–22812), force field parameters for methane adsorption in AlPOs were validated through a comparison to available experimental adsorption data. Afterwards, CO<sub>2</sub>/CH<sub>4</sub> and CH<sub>4</sub>/N<sub>2</sub> mixture isotherms were computed for all 53 frameworks for room temperature and total pressures up to 1000 kPa (10 bar), allowing the prediction of selectivities and working capacities for conditions that are relevant for pressure swing adsorption (PSA) and vacuum swing adsorption (VSA). For CO<sub>2</sub>/CH<sub>4 </sub>mixtures, the <b>GIS</b>, <b>SIV</b>, and <b>ATT</b> frameworks were found to have the highest selectivities and CO<sub>2 </sub>working capacities under VSA conditions, whereas several frameworks, among them <b>AFY</b>, <b>KFI</b>, <b>AEI</b>, and <b>LTA</b>, show higher working capacities under PSA conditions. For CH<sub>4</sub>/N<sub>2</sub> mixtures, all frameworks are moderately selective for methane over nitrogen, with <b>ATV</b> exhibiting a significantly higher selectivity than all other frameworks. While some of the most promising topologies are either not available in pure-AlPO<sub>4</sub> composition or collapse upon calcination, others can be synthesised and activated, rendering them interesting candidates for future experimental studies. In addition to predictions of mixture adsorption isotherms, further simulations were performed for four selected systems in order to investigate the microscopic origins of the macroscopic adsorption behaviour, <i>e.g. </i>with regard to the very high CH<sub>4</sub>/N<sub>2</sub> selectivity of <b>ATV</b> and the loading-dependent evolution of the heat of CO<sub>2</sub> adsorption and CO<sub>2</sub>/CH<sub>4</sub> selectivity of <b>AEI</b> and GME.</div>

Sign in / Sign up

Export Citation Format

Share Document