Physical and Chemical Sputtering at Very Low Ion Energy: the Importance of the Sputtering Threshold

1988 ◽  
Vol 129 ◽  
Author(s):  
Christoph Steinbruchel
Keyword(s):  
Threshold Energy ◽  
Surface Binding ◽  
Ion Energy ◽  
Chemical Sputtering ◽  
Surface Binding Energy ◽  
Physical Sputtering ◽  
Chemical Etch ◽  
Ion Energies ◽  
The Difference ◽  
Physical And Chemical

ABSTRACTA variety of data for physical etching (i.e. sputtering) and for ion-enhanced chemical etching of Si and SiO2 is analyzed in the very-low-ion-energy regime. Bombardment by inert ions alone, by reactive ions, and by inert ions in the presence of reactiveneutrals is considered. In all cases the etch yield follows a square root dependence on the ion energy all the way down to the threshold energy for etching. At the same time, the threshold energy has a non-negligible effect on the etch yield even at intermediate ion energies. The difference between physical and ion-enhanced chemical etch yields can be accounted for by a reduction in the average surface binding energy of the etch products and a corresponding reduction in the threshold energy for etching. These results suggest that, in general, the selectivity for ion-enhanced etch processes relative to physical sputtering can be increased significantly at low ion energy.

Universal Energy Dependence of Sputtering Yields At Low Ion Energy

1991 ◽  
Vol 223 ◽  
Author(s):  
J. Muri ◽  
Ch. Steinbrüchel
Keyword(s):  
Noble Gas ◽  
Large Body ◽  
Threshold Energy ◽  
Ion Energy ◽  
Chemical Sputtering ◽  
Physical Sputtering ◽  
Ion Energies ◽  
Atom Interaction ◽  
Physical And Chemical ◽  
Sputtering Yields

ABSTRACTSputtering yields Y(E)at ion energies E keV are shown to be described by the equation Y(E) = A(En - ) where A, n, and the threshold energy Eth are constants characteristic for a particular projectile/target combination. Examination of a wide variety of systems reveals that n = 0.5 provides an excellent universal representation of a large body of data, including physical sputtering of metals by noble gas ions, selfsputtering of metals, as well as physical and chemical sputtering of Si and SiO2. The above value for n is consistent with a 1/r4 power law atom-atom interaction potential within Sigmund's theory of sputtering. Another conclusion is that the effect of Eth on Y(E) must be taken into account at ion energies as high as 1 keV, not just near the sputtering threshold.

THE LUMINESCENCE RESPONSE OF PHOSPHORS TO LOW ENERGY ION BOMBARDMENT

1958 ◽  
Vol 36 (1) ◽  
pp. 104-116
Author(s):  
C. F. Eve ◽  
H. E. Duckworth
Keyword(s):  
Impact Parameter ◽  
Electronic Excitation ◽  
Threshold Energy ◽  
Low Energy ◽  
Experimental Results ◽  
Ion Energy ◽  
Small Impact ◽  
Ion Energies ◽  
Sensitive Function ◽  
Small Impact Parameter

The luminescence response of samples of ZnS:Ag and Zn2SiO4:Mn to bombardment with various ions was determined as a function of the ion energy. For ZnS:Ag, within the range of ion energies studied (E < 25 kev.), the luminescence response, L, is related to the ion energy, E, according to [Formula: see text]. E0 is a threshold energy which is not a very sensitive function of ion mass. For Zn2SiO4:Mn no threshold energy was observed except in the case of Li7+ ions, the lightest ions used with this phosphor. The experimental results for ZnS:Ag appear to be consistent with a theory in which it is assumed that the bombarding particles penetrate the phosphor as neutral atoms and produce luminescence by electronic excitation of the lattice atoms due to small impact parameter collisions.

Swift chemical sputtering of covalently bonded materials

2006 ◽  
Vol 78 (6) ◽  
pp. 1203-1211 ◽  
Author(s):  
K. Nordlund ◽  
E. Salonen ◽  
A. V. Krasheninnikov ◽  
J. Keinonen
Keyword(s):  
Hydrogenated Silicon ◽  
Erosion Rates ◽  
Bonded Materials ◽  
Chemical Sputtering ◽  
Amorphous Hydrogenated Silicon ◽  
Physical Sputtering ◽  
Covalently Bonded ◽  
Wide Range ◽  
Ion Energies ◽  
Atom Level

Numerous experiments have shown that low-energy H ions and neutrals can erode amorphous carbon at ion energies of 1-10 eV, where physical sputtering is impossible, but at erosion rates which are clearly higher than those caused by thermal ions. In this paper, we will first review our computer simulation work providing an atom-level mechanism for how this erosion occurs, and then present some new results for H and He bombardment of tungsten carbide and amorphous hydrogenated silicon (a-Si:H), which indicate the mechanism can be of importance in a wide range of covalently bonded materials. We also discuss how the presented mechanism relates to previously described abstraction and etching mechanisms.

scholarly journals Influence of the Bottom Color Modification and Material Color Modification Process on the Performance of Modified Poplar

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 660
Author(s):  
Qingqing Liu ◽  
Di Gao ◽  
Wei Xu
Keyword(s):  
Chemical Properties ◽  
Target Color ◽  
Modification Process ◽  
Red Color ◽  
The Difference ◽  
Pre Treatment ◽  
Physical And Chemical ◽  
Surface Differentiation ◽  
Color Modification ◽  
And Chemical Properties

According to the old surface coating process of European and American furniture, the surface of modified poplar is first differentiated pre-treatment, and then the bottom color modification and material color modification are respectively applied to the modified poplar after the surface differentiation treatment. The visual physical quantity and physical and chemical properties were measured and compared with mahogany, which is commonly used in old furniture in Europe and America to explore the effect of colorants and coloring steps, as well as different surface pretreatments on the coloring effect. Finally, it is concluded that continuous coloring operations can narrow the difference in brightness and red color value in the coloring layer of modified poplar and mahogany. Continuous coloring operations increase the difference between the yellow-green color values of modified poplar and mahogany. Therefore, the coloring difference between modified poplar and mahogany was affected by the colorant and coloring steps. Through color accumulation, the gap between the two in the target color coloring effect can be reduced, thereby reducing the difference between the coloring effect of modified poplar and mahogany.

scholarly journals Molecular gas in the northern nucleus of Mrk 273: Physical and chemical properties of the disc and its outflow

2018 ◽  
Vol 617 ◽  
pp. A20 ◽  
Author(s):  
R. Aladro ◽  
S. König ◽  
S. Aalto ◽  
E. González-Alfonso ◽  
N. Falstad ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Far Infrared ◽  
Molecular Gas ◽  
Dense Gas ◽  
Dynamical Mass ◽  
North West ◽  
North East ◽  
Dust Temperature ◽  
The Difference ◽  
Physical And Chemical

Aiming to characterise the properties of the molecular gas in the ultra-luminous infrared galaxy Mrk 273 and its outflow, we used the NOEMA interferometer to image the dense-gas molecular tracers HCN, HCO+, HNC, HOC+ and HC3N at ∼86 GHz and ∼256 GHz with angular resolutions of 4ʺ̣9 × 4ʺ̣5 (∼3.7 × 3.4 kpc) and 0ʺ̣61 × 0ʺ̣55 (∼460 × 420 pc). We also modelled the flux of several H2O lines observed with Herschel using a radiative transfer code that includes excitation by collisions and far-infrared photons. The disc of the Mrk 273 north nucleus has two components with decoupled kinematics. The gas in the outer parts (R ∼ 1.5 kpc) rotates with a south-east to north-west direction, while in the inner disc (R ∼ 300 pc) follows a north-east to south-west rotation. The central 300 pc, which hosts a compact starburst region, is filled with dense and warm gas, and contains a dynamical mass of (4 −5) × 109 M⊙, a luminosity of L′HCN = (3–4) × 108 K km s−1 pc2, and a dust temperature of 55 K. At the very centre, a compact core with R ∼ 50 pc has a luminosity of LIR = 4 × 1011 L⊙ (30% of the total infrared luminosity), and a dust temperature of 95 K. The core is expanding at low velocities ∼50–100 km s−1, probably affected by the outflowing gas. We detect the blue-shifted component of the outflow, while the red-shifted counterpart remains undetected in our data. Its cold and dense phase reaches fast velocities up to ∼1000 km s−1, while the warm outflowing gas has more moderate maximum velocities of ∼600 km s−1. The outflow is compact, being detected as far as 460 pc from the centre in the northern direction, and has a mass of dense gas ≤8 × 108 M⊙. The difference between the position angles of the inner disc (∼70°) and the outflow (∼10°) indicates that the outflow is likely powered by the AGN, and not by the starburst. Regarding the chemistry in Mrk 273, we measure an extremely low HCO+/HOC+ ratio of 10 ± 5 in the inner disc of Mrk 273.

TRUE AND APPARENT METABOLIZABLE ENERGY VALUES FOR POULTRY OF CANADIAN WHEATS AND OATS MEASURED BY BIOASSAY AND PREDICTED FROM PHYSICAL AND CHEMICAL DATA

1977 ◽  
Vol 57 (2) ◽  
pp. 365-374 ◽  
Author(s):  
I. R. SIBBALD ◽  
K. PRICE
Keyword(s):  
Metabolizable Energy ◽  
Chemical Data ◽  
Accuracy And Precision ◽  
Apparent Metabolizable Energy ◽  
The Difference ◽  
Variation Explained ◽  
Predicted Values ◽  
Naked Oats ◽  
Physical And Chemical ◽  
Better Than

Thirty samples of wheat and 28 samples of oats were assayed for true and apparent metabolizable energy (TME, AME). Within grains, the difference TME−AME increased with decreasing AME values; there is evidence that this trend is associated with reduced voluntary consumption of AME assay diets containing low energy grains. The TME and AME data were compared with ME values predicted from physical and chemical data describing the grains. Previously published prediction equations were tested and new equations were derived. Comparisons between predicted and observed data suggested that both the TME and AME values of wheat were predicted with insufficient accuracy and precision for practical use. Similar comparisons using the oat data showed high correlations between observed and predicted values, although the predictions were no more accurate than for wheat; however, when data describing four samples of naked oats were removed, the correlations were reduced substantially. Comparisons involving data for the hulled oats indicated that most equations were able to predict AME better than TME. Multiple regression analysis was used to identify those combinations of variables best able to predict TME data. No combination of variables was best for both wheat and oats. The combinations of variables used in published equations performed quite well. With four variables, the percentage of the TME variation explained was as high as 52 for wheat, 82 for oats and 64 for hulled oats. Predictions based on air-dry data are associated with higher correlations than those based on dry matter data, but the air-dry predictions are the less useful in practice. The reason for this is discussed.

scholarly journals Enhancement of Electrocatalytic Oxygen Evolution by Chiral Molecular Functionalization of Hybrid 2D Electrodes

2021 ◽  
Author(s):  
Yunchang Liang ◽  
Karla Banjac ◽  
Kévin Martin ◽  
Nicolas Zigon ◽  
Seunghwa Lee ◽  
...  
Keyword(s):  
Binding Energy ◽  
Oxygen Evolution ◽  
State Of The Art ◽  
Chiral Molecules ◽  
Surface Binding ◽  
Surface Binding Energy ◽  
Energy Conversion And Storage ◽  
Polarization Mechanism ◽  
And Storage ◽  
Unconventional Methods

A sustainable future requires highly efficient energy conversion and storage processes, where electrocatalysis plays a crucial role. The activity of an electrocatalyst is governed by the binding energy towards the reaction intermediates, while the scaling relationships prevent the improvement of a catalytic system over its volcano-plot limits. To overcome these limitations, unconventional methods that are not fully determined by the surface binding energy can be helpful. Here, we use organic chiral molecules, i.e., hetero-helicenes, to boost the oxygen evolution reaction (OER) by ca. 131.5 % (at the potential of 1.65 V vs. RHE) at state-of-the-art 2D catalysts via a spin-polarization mechanism. Our results show that chiral molecule-functionalization is able to increase the OER activity of catalysts beyond the volcano limits. A guideline for optimizing the catalytic activity via chiral molecular functionalization of hybrid 2D electrodes is given.

scholarly journals Relationships between physical and chemical characteristics and calculated metabolizable energy values in barley and oats with highly variable volume weights

1978 ◽  
Vol 50 (3) ◽  
pp. 276-284
Author(s):  
Maija-Liisa Salo
Keyword(s):  
Crude Protein ◽  
Starch Content ◽  
Metabolizable Energy ◽  
Chemical Characteristics ◽  
Crude Fibre ◽  
Variable Volume ◽  
Physical And Chemical Characteristics ◽  
Volume Weight ◽  
The Difference ◽  
Physical And Chemical

61 samples of barley with a volume weight of 38—75 kg/hl, and 49 oat samples with a volume weight of 40—65kg/hl were analyzed for physical and chemical characteristics. The approximate metabolizable energy (ME) value was calculated from the composition. The physical characteristics varied more, but the starch content less, in barley than in oats. There was also a negative correlation between starch and crude protein, and ether extract level in barley, but not in oats. Therefore the difference between the ME values of the best and the poorest samples was only 12% for barley, but 27 % for oats. Both the starch and the crude protein content predicted the ME value well: R2 of starch was 78—94 %, and that of crude fibre 55—84 %. The volume weight still gave a good indication for barley, but not at all for oats.

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