Carbon Research Articles

Molecular dynamics simulation of the interaction of an Ar/CH4 plasma with a surface: Growth, structure, and sputtering of the deposited C:H films

AbstractMolecular dynamics simulations were performed to investigate the growth of hydrocarbon films with a surface at temperatures from 300 to 1000 K. The results show that C2H is the main precursor of film growth. The formed C:H films are mainly unsaturated and dominated by double bonds and CN3 carbon atoms. The evolution of the C:H film is considered under the bombardment of the two major ions (Ar+ and C2H3+) with energies ranging from 50 to 100 eV. Film sputtering is significant above 50 eV, while at lower energies, the atoms of the C2H3+ ions can be incorporated and contribute to the growth.

Investigating the influence of oxygen-functionalized graphene nanosheets as an efficient multifunctional material for supercapacitor and electrocatalytic water splitting applications

Graphene oxide (GO) has received great research attention to develop its efficiency in electrochemical applications, particularly supercapacitor (SC) and water splitting systems. However, the presence of various oxygen moieties in GO drastically reduces the utilization of the material for commercial usages. In this work, we demonstrate the use of different sources to reduce graphene oxide (GO) nanosheets. The partially reduced GO not only improves the electronic conductivity but also boosts the interaction between the sp2- and sp3-hybridized carbon atoms. Benefiting from the partial reduction process, RGO is applied for the SC test in the three-electrode system and reveals a specific capacitance of 151.1 F g−1 at 1 A g−1 with a long cycle life. Furthermore, the asymmetric solid-state device can also be constructed from an M-GO cathode with an activated carbon anode, which displays a specific capacitance of 54.4 F g−1 at 1 A g−1, with a maximum energy density of 19.3 W h kg−1. Besides, the electrochemical water splitting performance of the partially reduced GO in KOH solution was also explored, confirming the effectiveness of the reduction process. This work highlights the successful preparation of RGO nanosheets, which may open a new route to constructing high-performance energy storage and conversion devices.

Tuning cross-plane thermal conductivity of multilayer graphene/h-BN vdW heterostructures via composition distribution

Nanomaterials with low thermal conductivity (TC) are ideal candidates as thermoelectric materials. In this direction, we design innovative multilayer graphene/h-BN (GBN) van der Waals (vdW) heterostructures with gradient composition distribution (C, B and N atoms), inspired by the newly synthesized boron carbonitride nanosheets. Three types of 26-layer GBN models are constructed and investigated, i.e. U-shape, X-shape, A-shape, representing uniform, symmetrical, and asymmetrical distributions of carbon atoms along the cross-plane direction, respectively. Based on non-equilibrium molecular dynamics (NEMD) simulation, we confirm that X-shape GBN model possess the lowest cross-plane TC, approximately 7 times smaller than that of the uniform U-shape graphene. The cross-plane TC can be further reduced by applying tensile strains or decreasing interlayer coupling strength. These findings elucidate the significant role the composition distribution plays in the thermal transport of GBN vdW heterostructures. However, the mechanical properties (Young's nodulus and tensile strength) of the new vdW heterostructures are insensitive to the composition distribution. Our work provides a new perspective for manipulating the interfacial thermal transport of multilayer GBN vdW heterostructures by means of material design and offers a useful guide for rationally designing thermoelectric materials with tailored thermal properties based on vdW heterostructures.

(4-Butyl-1-ethyl-1,2,4-triazol-5-ylidene)[(1,2,5,6-η)-cycloocta-1,5-diene](triphenylphosphane)iridium(I) tetrafluoridoborate

The title compound, [Ir(C8H12)(C8H15N3)(C18H15P)]BF4, a new triazole-based N-heterocyclic carbene iridium(I) cationic complex with a tetrafluoridoborate counter-anion, crystallizes with two cations and two anions in the asymmetric unit of space group Pc. The Ir centers of the cations have distorted square-planar conformations, formed by a bidentate (η2 + η2) cycloocta-1,5-diene (COD) ligand, an N-heterocyclic carbene and a triphenylphosphane ligand with the NHC carbon atom and P atom being cis. In the extended structure, non-classical C–H...F hydrogen bonds, one of which is notably short (H...F = 2.21 Å), link the cations and anions. The carbon atoms of one of the COD ligands are disordered over adjacent sites in a 0.62:0.38 ratio.

Antibacterial Effect, ADMET Properties, and Molecular Docking of Morpholine Derivatives with Varying Alkyl Chain Length Against Methicillin Resistant Staphylococcus aureus (MRSA) Isolates

AbstractIn this work, we synthesized a series of nine tetraalkylammonium salts derived from N‐methyl morpholine and assessed their antibacterial efficacy against Methicillin‐Resistant Staphylococcus aureus (MRSA). The investigated morpholinium cations differ by the length of one linear alkyl chain, which ranges from 1 to 18 carbon atoms. We found that compounds with alkyl chains in the n‐C12H25‐(n‐dodecyl) to C16H33‐(n‐hexadecyl) display the highest bactericidal effects, exhibiting Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of 3.9 μg/mL – surpassing the effectiveness of the commercial drug Linezolid. Conversely, compounds with shorter chains (<5 carbon atoms) are inactive against MRSA, establishing a clear structure‐activity relationship. Assays on A. salina reveal that short‐alkyl‐chain morpholinium derivatives, inactive against MRSA), are moderately toxic, while the strongest bactericides of our set demonstrate high or extreme toxicity to A. salina. Our findings underscore the potential of morpholine derivatives as a means to control Methicillin‐Resistant Staphylococcus aureus and pinpoint the need to develop safe applications for these compounds given their potential toxicity.

Learning with NanoKid: line-angle formula, chemical formula, molecular weight, and elemental analysis

Abstract The conversion from line-angle formula to chemical formula often poses a challenge for first-year nonchemistry majors. To address this, the authors developed an engaging exercise lecture that encompasses the conversion process and related chemistry concepts, including molecular weight and elemental analysis. Initially, the instructor reviews basic chemistry concepts with the students. Subsequently, students construct a NanoKid structure model using transistors and red LEDs connected by plastic tubes, representing carbon and oxygen atoms, respectively. By referencing their models, students identify the chemical formula of NanoKid, calculate its molecular weight, and perform elemental analysis under the guidance of the instructor. Additionally, they estimate the scale of the NanoKid model relative to the actual NanoKid molecule. The exercise promotes peer review among students and is completed within approximately 45 min. A post-lecture questionnaire revealed that the exercise was well-received by the students.

Design and synthesis of 6-C-alkyl-DMDP type nanomolar inhibitors of β-galactosidase and β-glucosidase based on broussonetine S and related derivatives

Broussonetine S (9), its C-1′ and C-10′ stereoisomers, and their corresponding enantiomers have been synthesized from enantiomeric arabinose-derived cyclic nitrones, with cross metathesis (CM), epoxidation and Keck asymmetric allylation as key steps. Glycosidase inhibition assays showed that broussonetine S (9) and its C-10′ epimer (10′-epi-9) were nanomolar inhibitors of bovine liver β-galactosidase and β-glucosidase; while their C-1′ stereoisomers were 10-fold less potent towards these enzymes. The glycosidase inhibition results and molecular docking calculations revealed the importance of the configurations of pyrrolidine core and C-1′ hydroxyl for inhibition potency and spectra. Together with the docking calculations we previously reported for α-1-C-alkyl-DAB derivatives, we designed and synthesized a series of 6-C-alkyl-DMDP derivatives with very simple alkyl chains. The inhibition potency of these derivatives was enhanced by increasing the length of the side chain, and maintained at nanomolar scale inhibitions of bovine liver β-glucosidase and β-galactosidase after the alkyl groups are longer than eight or ten carbons for the (6R)-C-alkyl-DMDP derivatives and their 6S epimers, respectively. Molecular docking calculations indicated that each series of 6-C-alkyl-DMDP derivatives resides in the same active site of β-glucosidase or β-galactosidase with basically similar binding conformations, and their C-6 long alkyl chains extend outwards along the hydrophobic groove with similar orientations. The increasing inhibitions of β-glucosidase and β-galactosidase with the number of carbon atoms in the side chains may be explained by improved adaptability of longer alkyl chains in the hydrophobic grooves. In addition, the lower β-glucosidase and β-galactosidase inhibitions of (6S)-C-alkyl-DMDP derivatives than their C-6 R stereoisomers can be attributed to the misfolding of their alkyl chains and resulted decreased adaptability in the hydrophobic groove. The work reported herein is valuable for design and development of more potent and selective inhibitors of β-galactosidase and β-glucosidase, which have potential in treatment of lysosomal storage diseases. Furthermore, part of the 6-C-alkyl-DMDP derivatives and their enantiomers were also tested as potential anti-cancer agents; all the compounds tested were found with moderate cytotoxic effects on MKN45 cells, which would indicate potential applications of these iminosugars in development of novel anticancer agents.

Effect of microstructure on wear resistance during high temperature carburization heat treatment of heavy-duty gear steel

To shorten the production cycle of heavy-duty gear steel and ensure its wear resistance, high temperature carburization, two high-temperature tempering, quenching, subzero treatment, and low-temperature tempering treatments were performed on 18Cr2Ni4WA steel in this work. The effect of surface precipitation phases and retained austenite on wear resistance after different heat treatments was studied throughout the process. The results show that an increase in the volume fraction (Vcar) and size (Dcar) of undissolved carbides and a decrease in the volume fraction of retained austenite (Vr) are beneficial to wear resistance. The Vcar increases from 3.4 % to 6.3 %, and the Dcar increases from 152 nm to 161 nm. The undissolved carbides are mainly cementite. The carbon content of retained austenite decreases from 1.02 % to 0.79 %, and Vr decreases from 40.6 % to 4.8 %. In addition, the microstrain increases from 0.386 % to 0.458 %, and the wear rate decreases from 0.49 × 10−8 mm3·N−1·mm−1 to 0.46 × 10−8 mm3·N−1·mm−1. The improvement in wear resistance is mainly attributed to solid solution strengthening of carbon atoms and precipitation strengthening of undissolved carbides.

Microstructure Evolution in Magnetron-Sputtered WC/SiC Multilayers with Varied WC Layer Thicknesses

Owing to the superior quality of the interface, WC/SiC multilayers have been considered promising candidates for X-ray Laue lenses in nano-focusing facilities and supermirrors in X-ray telescopes. To investigate the microstructure evolution in WC/SiC multilayers, a set of periodic multilayers was prepared with varied WC layer thicknesses ranging from 1.0 nm to 10.0 nm while keeping the thickness of the SiC layer constant at 3.0 nm. These samples were characterized using various analytical techniques, including GIXR, AFM, and XRD. An aperiodic WC/SiC multilayer sample was analyzed by TEM, EDX, and SAED to further study the chemical and structural changes while the thickness of the WC layer increased. The results indicate that the WC layer of the WC/SiC multilayer changes from amorphous to crystalline with increasing layer thickness. The crystalline state of the WC layer changes as the thickness increases. Meanwhile, the carbon atoms migrates noticeably to the interface as the WC layer becomes thicker, which smoothens the interfacial defects caused by the crystalline state transition. This migration of carbon is one of the key factors contributing to the smooth interface in WC/SiC multilayers.

Palladium-anchored calix[4]arene-derived porous organic polymer towards efficient hydrolytic cleavage of carbon disulfide

The release of carbon disulfide can have adverse effects on our environment and human health. The stability of carbon disulfide and the slow kinetics of hydrolysis can make it challenging to achieve efficient and practical cleavage of the CS bonds. Herein, a calix[4]arene-based porous organic polymer (CPOP-1) is innovatively synthesized through an optimized polycondensation reaction using C-Methylcalix[4]resorcinarene and hexafluoro-hexaazatriphenylene as monomers. Subsequently, palladium-induced calix[4]arene-based porous organic polymer was also synthesized via strong Pd−N coordination bonds to construct the metal-induced porous catalyst (CPOP-2). The polymeric catalyst active center [Pd2+(N^N)(NO3-)2] demonstrated outstanding catalytic hydrolysis performance (11.14 μmol g-1 h-1) in 10.5 h which is significantly enhanced by ca.13.2 times as compared to reported mononuclear Bpy-Pd(NO3)2, and 7.07 times than model trinuclear complex catalyst HATN-Pd-1, respectively. The control experiments revealed that POP catalysts showcased robust stability, prolonged effectiveness, and feasible recyclability during the hydrolytic cleavage of carbon disulfide at room temperature in aqueous solutions. Furthermore, the coordination environment of [Pd2+(N^N)] was validated through XPS, EXAFS, and isotope labeling measurements, and the hydrolysis cleavage products were confirmed e. g. CO2, sulfide, and protons. More importantly, a reaction mechanism was formulated coupled with theoretical calculations, and simulations. The proposed mechanism involves sequential OH- nucleophilic attacks on the carbon atoms of insert-coordinated CS2 and COS, leading to the cleavage of double CS bonds and the formation of CO bonds. The concurrent dissociation of the C−S bond and liberation of CO2 result in an intermediate structure characterized by [(N^N)Pd2+](SH-)2. This intermediate motif serves as the source of the thermodynamic driving force for the reaction.

Graphitized Carbon-Supported Co@Co3O4 for Ozone Decomposition over the Entire Humidity Range.

Ground-level ozone (O3) pollution has emerged as a significant concern due to its detrimental effects on human health and the ecosystem. Catalytic removal of O3 has proven to be the most efficient and cost-effective method. However, its practical application faces substantial challenges, particularly in relation to its effectiveness across the entire humidity range. Herein, we proposed a novel strategy termed "dual active sites" by employing graphitized carbon-loaded core-shell cobalt catalysts (Co@Co3O4-C). Co@Co3O4-C was synthesized via the pyrolysis of a Co-organic ligand as the precursor. By utilizing this approach, we achieved a nearly constant 100% working efficiency of the Co@Co3O4-C catalyst for catalyzing O3 decomposition across the entire humidity range. Physicochemical characterization coupled with density functional theory calculations elucidates that the presence of encapsulated metallic Co nanoparticles enhances the reactivity of the cobalt oxide capping layer. Additionally, the interface carbon atom, strongly influenced by adjacent metallic Co nuclei, functions as a secondary active site for the decomposition of O3 decomposition. The utilization of dual active sites effectively mitigates the competitive adsorption of H2O molecules, thus isolating them for adsorption in the cobalt oxide capping layer. This optimized configuration allows for the decomposition of O3 without interference from moisture. Furthermore, O3 decomposition monolithic catalysts were synthesized using a material extrusion-based three-dimensional (3D) printing technology, which demonstrated a low pressure drop and exceptional mechanical strength. This work provides a "dual active site" strategy for the O3 decomposition reaction, realizing O3 catalytic decomposition over the entire humidity range.

Counterintuitive chemoselectivity in the reduction of carbonyl compounds.

The reactivity of carbonyl functional groups largely depends on the substituents on the carbon atom. Reversal of the commonly accepted order of reactivity of different carbonyl compounds requires novel synthetic approaches. Achieving selective reduction will enable the transformation of carbon resources such as plastic waste, carbon dioxide and biomass into valuable chemicals. In this Review, we explore the reduction of less reactive carbonyl groups in the presence of those typically considered more reactive. We discuss reductions, including the controlled reduction of ureas, amides and esters to aldehydes, as well as chemoselective reductions of carbonyl groups, including the reduction of ureas over carbamates, amides and esters; the reduction of amides over esters, ketones and aldehydes; and the reduction of ketones over aldehydes.

Ionizing radiation exposure on Arrokoth shapes a sugar world

The Kuiper Belt object (KBO) Arrokoth, the farthest object in the Solar System ever visited by a spacecraft, possesses a distinctive reddish surface and is characterized by pronounced spectroscopic features associated with methanol. However, the fundamental processes by which methanol ices are converted into reddish, complex organic molecules on Arrokoth's surface have remained elusive. Here, we combine laboratory simulation experiments with a spectroscopic characterization of methanol ices exposed to proxies of galactic cosmic rays (GCRs). Our findings reveal that the surface exposure of methanol ices at 40 K can replicate the color slopes of Arrokoth. Sugars and their derivatives (acids, alcohols) with up to six carbon atoms, including glucose and ribose-fundamental building block of RNA-were ubiquitously identified. In addition, polycyclic aromatic hydrocarbons (PAHs) with up to six ring units (13C22H12) were also observed. These sugars and their derivatives along with PAHs connected by unsaturated linkers represent key molecules rationalizing the reddish appearance of Arrokoth. The formation of abundant sugar-related molecules dubs Arrokoth as a sugar world and provides a plausible abiotic preparation route for a key class of biorelevant molecules on the surface of KBOs prior to their delivery to prebiotic Earth.

Theoretical studies on the kinetics and mechanism of hydroxyl radical reaction with quinclorac and quinmerac herbicides in aqueous media

AbstractThe kinetic and mechanistic studies for the reaction of hydroxyl radical with two quinoline based herbicides, namely, quinclorac and quinmerac has been performed using various computational methods in aqueous media. Geometry optimizations were performed using Density Functional Theory (DFT) methods including water as the solvent. Local reactivity parameters of these herbicides towards the •OH radical are predicted using condensed Fukui function. Single point energies of various species were calculated using double hybrid method, namely, B2PLYP–D for better accuracy. The pKa values for these acid based herbicides allow them to exist in deprotonated form in aqueous condition. Hence, the calculations are also performed for the deprotonated or the anionic form apart from the neutral species. Individual rate coefficients for •OH radical addition reaction with each carbon atoms were evaluated using conventional transition state theory using one–dimensional tunneling corrections. The solvent effect on reaction is implemented through Collins–Kimball formulations. Both the approaches, namely, the Fukui index and individual rate constant determination confirms that the most reactive site for the •OH radical addition in these two herbicide is the carbon atom attached to the COOH group. The total rate constant for the •OH radical reaction with both neutral and anionic forms of these two herbicides are relatively high and equal to its diffusion‐limit value. Evaluation of the ecotoxicities of the parent herbicides and their OH adducts is estimated using the structure–activity relationship concept.

Effect of interlayer bonded bilayer graphene on friction

Abstract We study the friction properties of interlayer bonded bilayer graphene by simulating the movement of slider on the surface of bilayer graphene using molecular dynamics. The results show that the presence of the interlayer covalent bonds due to the local sp3 hybridization of carbon atoms in the bilayer graphene seriously reduced the frictional coefficient of the bilayer graphene surface to 30%, depending on the coverage of interlayer sp3 bonds and normal loads. For a certain coverage of interlayer sp3 bonds, when the normal load of the slider reaches a certain value, the surface of this interlayer bonded bilayer graphene will lose the friction reduction effect on the slider. Our findings provide guidance for the regulation and manipulation of the frictional properties of bilayer graphene surfaces through interlayer covalent bonds, which may be useful for the application of friction related graphene based nanodevices.

Valorization of lignite to arene-rich compounds via two-stage selective cleavage of C-O bridged bonds over Co-MoS2

Directly converting lignite into arenes as commodity chemicals and drop-in fuels is a highly desirable target for researchers. However, this is severely limited by the presence of stable inter unit C-O linkages in lignite. Herein, a highly active catalyst, Co-MoS2, has been designed and prepared to be used for the selective catalytic cleavage of inter unit C-O bridged bonds (BBs) in the conversion of Naomaohu (NMH), a lignite, to yield arenes. Both catalytic hydrogenation conversion (CHC) and thermal dissolution (a non-catalytic process, named NCHC) of NMH were conducted using n-hexane as the solvent. The soluble fractions from the first stage of NCHC (SFNCHC-1) and CHC (SFCHC-1), as well as the second stage of NCHC (SFNCHC-2) and CHC (SFCHC-2) were obtained using the same solvent. After the first-stage catalytic treatment, the relative contents of arenes and alkanes in SFCHC-1 increased by 16.7 % and 9.3 %, respectively, compared to those in SFNCHC-1, and the relative content of oxygen-containing compounds (OCCs), such as alcohols, phenols, esters, ketones, acids, and furans, decreased by 13.2 %. For the second-stage conversion, the relative contents of arenes and alkanes in SFCHC-2 were 53.5 % and 15.5 % higher than those in SFNCHC-2, and the relative contents of OCCs was only 6.6 % in SFCHC-2. The catalytic mechanisms of cleavage of C-O BBs and deoxygenation were proposed based on the CHC of model compounds and density functional theory (DFT) calculation. The adsorption of OCCs and the activation of released hydrogen radical (H·) by Co-MoS2, followed by H· addition to the carbon atom connected to oxygen in C-O BBs and oxygen-containing functional groups, are crucial for the cleavage of C-O BBs and formation of deoxygenated compounds, particularly arenes.

Hydrogen Peroxide-Induced Overoxidation of Fe-N-C Catalysts: Implications for ORR Activity.

Fe-N-C (iron-nitrogen-carbon) electrocatalysts have emerged as promising alternatives to precious metals for the oxygen reduction reaction (ORR), but they remain insufficiently stable for widespread adoption in fuel cell technologies. One plausible mechanism to explain this lack of stability, and the associated catalyst degradation, is oxidative attack on the catalyst surface by hydrogen peroxide, a non-selective byproduct of the ORR. In this work, we perform a detailed analysis of this degradation mechanism, using a combination of periodic Density Functional Theory (DFT) calculations and ab-initio molecular dynamics (AIMD) simulations to probe the thermodynamics and kinetics of hydrogen peroxide activation on a series of candidate active sites for the Fe-N-C catalyst. The results demonstrate that carbon atoms neighbouring FeN4 active sites can be strongly over-oxidized via formation of hydroxyl or epoxy groups when hydrogen peroxide is present in the electrolyte. In most cases, the interaction between the over-oxidizing groups and the ORR reaction intermediates reduces the ORR activity, and we further propose that the over-oxidized sites are likely precursors to irreversible carbon corrosion and further catalyst deactivation.

High heat resistance and neutron shielding performance epoxy with carborane hybridized crosslinked network

Epoxy resin has gained significant attention in aviation equipment, coatings and electronic packaging materials due to its exceptional processability, adhesion and mechanical properties. However, its thermal resistance property and glass transition temperature (Tg) were relatively lower than cyanate resin (CE), polyimides (PI) and phenolic resins (PF), which largely restricts its application range. In this work, we had developed a new structural heat-and-shielding integrated epoxy resin via the design of carboranes-epoxy network. Benefiting from the structure of carborane, the thermal residual weight of the obtained epoxy reached 64.57 %, with a carbon atom protection rate of 45.47 % in air atmosphere at 800 °C, showing better thermal resistance property than most CE, PI and PF. And the Tg of the new epoxy was not observed within the tested temperature range (50–250 °C). Additionally, the introduction of carborane structures enhances the neutron shielding performance of the material (38.46 % enhanced). The reinforcement mechanisms of these above properties are systematically investigated. It's excepted that our work could provide some ideas to prepare structural -functional integrated epoxy and promote the development of carborane related materials.

Vertical and radial distribution of atomic carbon in HD 163296

Context. In protoplanetary disks, atomic carbon is expected to originate from the photo dissociation region at the disk surface where CO is dissociated by ultraviolet (UV) photons coming from the stellar, or external interstellar, radiation field. Even though atomic carbon has been detected in several protoplanetary disks, there is a lack of spatially resolved observations of it. Aims. For the HD 163296 protoplanetary disk, we aim to obtain both the radial and vertical structure of [CI] = 3P1 − 3P0 line emission and perform the first direct comparison of this tracer with the optically thick line emission 12CO J = 2 − 1. Methods. We used archival ALMA data for [CI] = 3P1 − 3P0 and previously published12 CO J = 2 − 1 data in HD 163296. Through the disksurf software, we extracted the vertical structure; meanwhile, we obtained the radial profiles directly from imaging. Brand new DALI modeling was employed to perform a direct comparison with the data. Results. We find that these tracers are colocated radially but not vertically, where the 12CO J = 2 − 1 emission is, on average, located at higher altitudes, as is also the case for other tracers in the same disk. Conclusions. Due to this difference in the vertical height of the emission, the optically thick 12CO J = 2 − 1 emission line appears to trace the highest altitudes, despite the expected formation mechanism of [CI] in the disk. The latter phenomena may be due to efficient mixing of the upper layers of the disk, or UV photons penetrating deeper than we expected.

On working gas rarefaction in high power impulse magnetron sputtering

The ionization region model (IRM) is applied to explore working gas rarefaction in high power impulse magnetron sputtering discharges operated with graphite, aluminum, copper, titanium, zirconium, and tungsten targets. For all cases the working gas rarefaction is found to be significant, the degree of working gas rarefaction reaches values of up to 83%. The various contributions to working gas rarefaction, including electron impact ionization, kick-out by the sputtered species or hot argon atoms, and diffusion, are evaluated and compared for the different target materials, and over a range of discharge current densities. The relative importance of the various processes varies between different target materials. In the case of a graphite target with argon as the working gas at 1 Pa, electron impact ionization (by both primary and secondary electrons) is the dominating contributor to working gas rarefaction, with over 90% contribution, while the contribution of sputter wind kick-out is small <10 %. In the case of copper and tungsten targets, the kick-out dominates, with up to ∼60% contribution at 1 Pa. For metallic targets the kick-out is mainly due to metal atoms sputtered from the target, while for the graphite target the small kick-out contribution is mainly due to kick-out by hot argon atoms and to a smaller extent by carbon atoms. The main factors determining the relative contribution of the kick-out by the sputtered species to working gas rarefaction appear to be the sputter yield and the working gas pressure.