scholarly journals Raman Spectroscopy of Amorphous Carbon

1997 ◽  
Vol 498 ◽  
Author(s):  
D. R. Tallant ◽  
T. A. Friedmann ◽  
N. A. Missert ◽  
M. P. Siegal ◽  
J. P. Sullivan
Keyword(s):  
Raman Spectroscopy ◽  
Amorphous Carbon ◽  
Hydrogen Content ◽  
Level Structure ◽  
Chemical Properties ◽  
High Energy ◽  
Film Deposition ◽  
Forms Of Carbon ◽  
The Impact ◽  
Deposition Conditions

ABSTRACTAmorphous carbon is an elemental form of carbon with low hydrogen content, which may be deposited in thin films by the impact of high energy carbon atoms or ions. It is structurally distinct from the more well-known elemental forms of carbon, diamond and graphite. It is distinct in physical and chemical properties from the material known as diamond-like carbon, a form which is also amorphous but which has a higher hydrogen content, typically near 40 atomic percent. Amorphous carbon also has distinctive Raman spectra, whose patterns depend, through resonance enhancement effects, not only on deposition conditions but also on the wavelength selected for Raman excitation. This paper provides an overview of the Raman spectroscopy of amorphous carbon and describes how Raman spectral patterns correlate to film deposition conditions, physical properties and molecular level structure.

ARSENIC-INDUCED DOWNSHIFT OF RAMAN BAND POSITIONS FOR PYRITE

2020 ◽  
Vol 115 (7) ◽  
pp. 1589-1600
Author(s):  
Qiaoqiao Zhu ◽  
Nigel J. Cook ◽  
Guiqing Xie ◽  
Benjamin P. Wade ◽  
Cristiana L. Ciobanu
Keyword(s):  
Raman Spectroscopy ◽  
Environmental Science ◽  
Raman Band ◽  
Eastern China ◽  
Chemical Properties ◽  
Minor Element ◽  
Minor Elements ◽  
Band Position ◽  
Wide Range ◽  
The Impact

Abstract Pyrite commonly incorporates a wide range of trace and minor elements, which in turn may modify some of the mineral’s physical and chemical properties. Published band position data for the Raman spectra of pyrite show a wide variation, and the relationship between band position and the trace/minor element incorporation in pyrite is poorly constrained until now. This prompted a case study on pyrite with varying As content from the Shizilishan Sr-(Pb-Zn) deposit, eastern China, combining electron probe microanalysis with Raman spectroscopy. Results show a significant correlation, with a major downshift (~10 cm–1) of the positions of all three Raman bands with increase of As content from below 0.05 to 4.89 wt % in pyrite. This phenomenon is attributed to increased bond lengths and local distortions within an expanded pyrite crystal structure. Results highlight the potential that Raman spectroscopy offers to estimate the contents of trace/minor elements—especially As—in pyrite. Given that substitution of As into pyrite often facilitates co-incorporation of both economically useful (Au) and environmentally significant elements (Hg and Tl), Raman methodology could provide valuable, rapid assessment of pyrite chemistry in both gold deposit exploration and environmental science, although the impact of laser heating and mechanical polishing needs to be avoided or effectively reduced. Raman spectroscopy may also find a valuable future role within semiautomated multispectral analytical platforms that can generate close- to-real-time geologic information on freshly drilled core directly at the drill site or in outcrop.

scholarly journals Comparison of Carbon Thin Films with Low Secondary Electron Yield Deposited in Neon and Argon

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 884
Author(s):  
Yuxin Zhang ◽  
Yigang Wang ◽  
Sihui Wang ◽  
Wei Wei ◽  
Xiaoqin Ge ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Amorphous Carbon ◽  
Secondary Electron ◽  
High Energy ◽  
Carbon Coatings ◽  
Secondary Electron Yield ◽  
Electron Yield ◽  
Carbon Thin Films ◽  
Amorphous Carbon Coatings

Modification of vacuum chamber surface properties by introducing a layer of material with low secondary electron yield (SEY) is one of the most useful solutions to suppress the electron-cloud in high-energy particle accelerators. In the present work, amorphous carbon thin films have been produced by DC magnetron sputtering with Neon and Argon sputtering gases. Microstructures of the thin films have been characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sp2 and sp3 hybridized carbon atoms are evaluated using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The amorphous carbon coatings comprise tiny granularities of tens of nanometers. The amorphous carbon films show more graphite-like properties as revealed by XPS and Raman spectroscopy. The secondary electron emission measurement results indicate that amorphous carbon coatings present SEY of <1.2. The thin film deposited by Ne exhibits a higher sp2 hybridization content, leading to a slightly lower SEY compared with the film produced with Ar.

Hydrogen content estimation of hydrogenated amorphous carbon by visible Raman spectroscopy

2004 ◽  
Vol 96 (11) ◽  
pp. 6348-6352 ◽  
Author(s):  
G. Adamopoulos ◽  
J. Robertson ◽  
N. A. Morrison ◽  
C. Godet
Keyword(s):  
Raman Spectroscopy ◽  
Amorphous Carbon ◽  
Hydrogen Content ◽  
Hydrogenated Amorphous Carbon ◽  
Hydrogenated Amorphous

STUDY ON ENERGY EFFICIENCY OF A-TIG WELDING OF STAINLESS STEELS USING INDIVIDUAL FLUX-OXIDES. PART 2. INFLUENCE OF THERMODYNAMIC AND PHYSICO-CHEMICAL PROPERTIES OF FLUX-OXIDES

2019 ◽  
Vol 6 (3) ◽  
pp. 32-38
Author(s):  
RUSTAM MANNAPOVICH SAIDOV ◽  
DURDONA RUSTAMOVNA KOMILOVA ◽  
MARIO KUSCH ◽  
PETER MAYR ◽  
KEVIN HOEFER
Keyword(s):  
Energy Efficiency ◽  
Chemical Properties ◽  
High Energy ◽  
Tig Welding ◽  
Depth Of Penetration ◽  
Welding Arc ◽  
Physico Chemical ◽  
A Tig Welding ◽  
The Impact ◽  
Individual Flux

This paper presents the results of studies on the influence of thermodynamic and physico-chemical properties of individual flux-oxides on the energy efficiency of the arc A-TIG welding of stainless steel CrNi18-10. The obtained results of the research allowed to reveal the criteria for evaluating the energy efficiency of the arc A-TIG welding on the depth of penetration of the welded metal and to determine the impact of thermodynamic and physico-chemical properties of individual flux oxides on the energy efficiency of the penetration capability of the welding arc for different welding energies. The requirements to thermodynamic and physico-chemical properties of individual fluxes-oxides are also revealed, which provide high energy efficiency of arc penetration capability during A-TIG welding.

scholarly journals The Impact of Filler Geometry on Polylactic Acid-Based Sustainable Polymer Composites

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 149
Author(s):  
Karol Leluk ◽  
Stanisław Frąckowiak ◽  
Joanna Ludwiczak ◽  
Tomasz Rydzkowski ◽  
Vijay Kumar Thakur
Keyword(s):  
Polymer Composites ◽  
Polylactic Acid ◽  
Matrix Material ◽  
Chemical Properties ◽  
Precipitated Calcium Carbonate ◽  
Cellulose Fibres ◽  
Shape Factors ◽  
Pure Cellulose ◽  
Physico Chemical ◽  
The Impact

Recently, biocomposites have emerged as materials of great interest to the scientists and industry around the globe. Among various polymers, polylactic acid (PLA) is a popular matrix material with high potential for advanced applications. Various particulate materials and nanoparticles have been used as the filler in PLA based matrix. One of the extensively studied filler is cellulose. However, cellulose fibres, due to their hydrophilic nature, are difficult to blend with a hydrophobic polymer matrix. This leads to agglomeration and creates voids, reducing the mechanical strength of the resulting composite. Moreover, the role of the various forms of pure cellulose and its particle shape factors has not been analyzed in most of the current literature. Therefore, in this work, materials of various shapes and shape factors were selected as fillers for the production of polymer composites using Polylactic acid as a matrix to fill this knowledge gap. In particular, pure cellulose fibres (three types with different elongation coefficient) and two mineral nanocomponents: precipitated calcium carbonate and montmorillonite were used. The composites were prepared by a melt blending process using two different levels of fillers: 5% and 30%. Then, the analysis of their thermomechanical and physico-chemical properties was carried out. The obtained results were presented graphically and discussed in terms of their shape and degree of filling.

scholarly journals Shock interactions in inviscid air and $$\hbox {CO}_2$$–$$\hbox {N}_2$$ flows in thermochemical non-equilibrium

Shock Waves ◽  
2021 ◽  
Author(s):  
C. Garbacz ◽  
W. T. Maier ◽  
J. B. Scoggins ◽  
T. D. Economon ◽  
T. Magin ◽  
...  
Keyword(s):  
Chemical Species ◽  
High Energy ◽  
Ideal Gas ◽  
Shock Interaction ◽  
Interaction Patterns ◽  
Shock Interactions ◽  
Wave Interference ◽  
Type V ◽  
The Impact ◽  
Non Equilibrium

AbstractThe present study aims at providing insights into shock wave interference patterns in gas flows when a mixture different than air is considered. High-energy non-equilibrium flows of air and $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 over a double-wedge geometry are studied numerically. The impact of freestream temperature on the non-equilibrium shock interaction patterns is investigated by simulating two different sets of freestream conditions. To this purpose, the SU2 solver has been extended to account for the conservation of chemical species as well as multiple energies and coupled to the Mutation++ library (Multicomponent Thermodynamic And Transport properties for IONized gases in C++) that provides all the necessary thermochemical properties of the mixture and chemical species. An analysis of the shock interference patterns is presented with respect to the existing taxonomy of interactions. A comparison between calorically perfect ideal gas and non-equilibrium simulations confirms that non-equilibrium effects greatly influence the shock interaction patterns. When thermochemical relaxation is considered, a type VI interaction is obtained for the $$\hbox {CO}_2$$ CO 2 -dominated flow, for both freestream temperatures of 300 K and 1000 K; for air, a type V six-shock interaction and a type VI interaction are obtained, respectively. We conclude that the increase in freestream temperature has a large impact on the shock interaction pattern of the air flow, whereas for the $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 flow the pattern does not change.

scholarly journals Coir Fibers Treated with Henna as a Potential Reinforcing Filler in the Synthesis of Polyurethane Composites

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1128
Author(s):  
Sylwia Członka ◽  
Anna Strąkowska ◽  
Agnė Kairytė
Keyword(s):  
Mechanical Properties ◽  
High Energy ◽  
Dynamic Mechanical Properties ◽  
Milling Process ◽  
Coir Fiber ◽  
Lawsonia Inermis ◽  
Coir Fibers ◽  
Mechanical Performances ◽  
The Impact ◽  
Reinforcing Filler

In this study, coir fibers were successfully modified with henna (derived from the Lawsonia inermis plant) using a high-energy ball-milling process. In the next step, such developed filler was used as a reinforcing filler in the production of rigid polyurethane (PUR) foams. The impact of 1, 2, and 5 wt % of coir-fiber filler on structural and physico-mechanical properties was evaluated. Among all modified series of PUR composites, the greatest improvement in physico-mechanical performances was observed for PUR composites reinforced with 1 wt % of the coir-fiber filler. For example, on the addition of 1 wt % of coir-fiber filler, the compression strength was improved by 23%, while the flexural strength increased by 9%. Similar dependence was observed in the case of dynamic-mechanical properties—on the addition of 1 wt % of the filler, the value of glass transition temperature increased from 149 °C to 178 °C, while the value of storage modulus increased by ~80%. It was found that PUR composites reinforced with coir-fiber filler were characterized by better mechanical performances after the UV-aging.

scholarly journals Body Mass, Physical Activity and Eating Habits Changes during the First COVID-19 Pandemic Lockdown in Poland

2021 ◽  
Vol 18 (11) ◽  
pp. 5682
Author(s):  
Hubert Dobrowolski ◽  
Dariusz Włodarek
Keyword(s):  
Physical Activity ◽  
Body Weight ◽  
Body Mass ◽  
Social Life ◽  
Eating Habits ◽  
High Energy ◽  
High Energy Density ◽  
Average Weight ◽  
Study Participants ◽  
The Impact

The outbreak of the COVID-19 pandemic caused a number of changes in social life around the world. In response to the growing number of infections, some countries have introduced restrictions that may have resulted in the change of the lifestyle. The aim of our study was to investigate the impact of the lockdown on body weight, physical activity and some eating habits of the society. The survey involving 183 people was conducted using a proprietary questionnaire. The mean age of the study participants was 33 ± 11 and mean height 169 ± 8 cm. An average increase in body weight was observed in 49.18% by 0.63 ± 3.7 kg which was the result of a decrease in physical activity and an increase in food consumption. We also observed a decrease in PAL from 1.64 ± 0.15 to 1.58 ± 0.13 and changes in the amount of food and individual groups of products consumption, including alcohol. Among the study participants who did not lose body mass, there was an average weight gain of 2.25 ± 2.5 kg. In conclusion, an increase of weight was shown in about half of the respondents in the study group which was associated with a decrease in physical activity and an increase in the consumption of total food and high energy density products.

scholarly journals High-energy operator product expansion at sub-eikonal level

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Giovanni Antonio Chirilli
Keyword(s):  
Operator Product Expansion ◽  
Evolution Equations ◽  
Energy Operator ◽  
High Energy ◽  
Structure Functions ◽  
Distribution Functions ◽  
Impact Factors ◽  
Operator Product ◽  
The Impact ◽  
New Distribution

Abstract The high energy Operator Product Expansion for the product of two electromagnetic currents is extended to the sub-eikonal level in a rigorous way. I calculate the impact factors for polarized and unpolarized structure functions, define new distribution functions, and derive the evolution equations for unpolarized and polarized structure functions in the flavor singlet and non-singlet case.

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