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A diamond film was synthesized by chemical vapor deposition, where a hot graphite plate was used to thermally activate methane and hydrogen. The effect of parameters on the diamond films grown, such as pressure ranging from 40 to 100 torr, methane concentration in hydrogen varying from 0.5 to 2 vol %, and substrate temperatures from 1020 to 1140 °C, were studied. Diamond films with nanocrystalline to polycrystalline crystal sizes were obtained. A maximum growth rate of 0.8 μm/h was obtained, and the quality is comparable to diamond films synthesized by the hot metal filament chemical vapor deposition method. In contrast to the hot filament method, this method does not use a metallic filament as thermal activator. Therefore, the diamond films contain no metal contaminants and thus can be used for electronic and biomedical applications. The absence of metal contaminants was confirmed using different methods.

The structural investigation of the a-Si:H material, deposited at different pressures by PECVD process, has been carried out to analyze the signatures of diffused intermediate sort of crystalline phases within the amorphous silicon matrix. Raman characterization along with the Photoluminescence (PL) and spectroscopic ellipsometry studies were carried out to understand the microstructuree of these films. From Raman analysis the material was found to have indistinguishable crystalline phase, which can also be named as “intermediate amorphous phase” (a phase defined between amorphous and ultra nano-crystalline silicon) with crystalline volume fractions as 56 % and 62 % for 0.23 Torr and 0.53 Torr respectively. Here the contribution of ultra nano-crystallites results in higher crystalline fraction, which is not visibly revealed from the Raman spectra due to its sub nano-crystallite characteristics. For the film deposited at 0.53 Torr stable photo-conductance in conjunction with high photo-response under 10 hour light soaking has been observed, which is as expected due to high crystalline volume fraction. The presence of these phases might be the possible reason for the distinct device characteristics though having nearly the similar electrical properties (photo-response ~10 4 ). These studies will help to make improvement in the individual layer properties, other than the interface effect, in the fabrication of efficient p-i-n solar cells. Copyright © 2016 VBRI Press

Electron-beam plasma (EBP) inside dielectric containers is considered in the context of the plasma chemical reactors design. Both still and intermittent electron beams (EBs) were used to excite strongly nonequilibrium plasmas by their injection into still or moving plasma generating media. The EB was injected along a cylindrical vessel or channel filled with a gas at pressure up to 50 Torr. Additives (extra gases, vapors, or sprayed liquids) were injected into the container, if required, and an external electromagnetic field could be superimposed on the EBP. Influence of the additives, gas flow velocity, external electromagnetic field, and the EB pulses (in the intermittent modes of the EBP generation) are considered in terms of plasma density control and plasma decay characteristics. The instabilities in the EBP filling the dielectric container are described. Basic configuration of the experimental setup and experimental arrangement are given; a number of images of the plasmas in various regimes of the setup operation are presented.

The kinetics of successive reactions of acetylene (C2H2) initiated on either vanadium or iron atomic cations have been investigated under thermal conditions using the variable-ion source and temperature-adjustable selected-ion flow tube apparatus. Consistent with the literature results, the reaction of Fe+ + C2H2 primarily yields Fe+(m/z = (C2H2)3); however, analysis via quantum chemical calculations and statistical modeling shows that the mechanism does not form benzene upon the third acetylene addition. The kinetics are more consistent with successive addition of three acetylene molecules, yielding Fe+(C2H2)3, followed by an addition of a fourth acetylene molecule, initiating cyclotrimerization, yielding either Fe+(C2H2) + neutral benzene or Fe+(Bz) + acetylene, where Bz is a benzene ligand. In contrast, the reaction of V+ + C2H2 yields products via successive associations V+(m/z = (C2H2)n) either with or without a bimolecular step involving loss of one H2 and V+C2(m/z = (C2H2)m), where n and m extend at least up to 11 under conditions of 0.32 Torr at 300 K. Stabilized V+(Bz) is not a significant intermediate in the association mechanism. We propose a plausible mechanism for the generation of neutral benzene in this reaction and compare with the Fe+ results. The reaction steps that produce benzene result in turnover of the single-atom catalyst, and the large hydrocarbons produced that remain associated to the catalyst are proposed to be polycyclic aromatic hydrocarbons.

Heteroepitaxial growth of Ge films on Si is necessary for the progress of integrated Si photonics technology. In this work, an in-house assembled plasma enhanced chemical vapor deposition reactor was used to grow high quality epitaxial Ge films on Si (100) substrates. Low economic and thermal budget were accomplished by the avoidance of ultra-high vacuum conditions or high temperature substrate pre-deposition bake for the process. Films were deposited with and without plasma assistance using germane (GeH4) precursor in a single step at process temperatures of 350–385 °C and chamber pressures of 1–10 Torr at various precursor flow rates. Film growth was realized at high ambient chamber pressures (&gt, 10−6 Torr) by utilizing a rigorous ex situ substrate cleaning process, closely controlling substrate loading times, chamber pumping and the dead-time prior to the initiation of film growth. Plasma allowed for higher film deposition rates at lower processing temperatures. An epitaxial growth was confirmed by X-Ray diffraction studies, while crystalline quality of the films was verified by X-ray rocking curve, Raman spectroscopy, transmission electron microscopy and infra-red spectroscopy.

In this article, we report a wafer-level packaged Pirani vacuum gauge using the proprietary InvenSense CMOS MEMS technology. The micro Pirani vacuum gauge features three serpentine-shaped molybdenum thermistors on the suspended silicon-on-insulator (SOI) bridges, while the wiring gap of each serpentine-shaped silicon microbridge is 1.6 ${ {\mu }}\text{m}$ . For the vacuum range of $5\times 10^{-{4}}$ –760 Torr, the CMOS MEMS Pirani gauge configured with a constant temperature interface circuit achieves a sensitivity of 0.414 V/Torr in a very fine vacuum regime, while its heating power is less than 21.3 mW. Moreover, the measured output of the micro Pirani gauge shows good agreement with a semi-empirical model, while the model predicts that the proposed Pirani gauge can measure a vacuum pressure as low as $2.6\times 10^{-{4}}$ Torr. The performance achieved by this Pirani vacuum gauge combined with its high level of integration makes it a promising Internet of Things (IoT) sensing node for vacuum monitoring in the industry.

Hydrogen chloride (HCl) contributes substantially to the atmospheric Cl; both species could affect the composition of Earth's atmosphere and the fate of pollutants. Here, we present the kinetics study for syn-CH3CHOO reaction with HCl using experimental measurement and theoretical calculations. The experiment was conducted in a flow tube reactor at a pressure of 10 Torr and temperatures ranging from 283 to 318 K by using the OH laser-induced fluorescence (LIF) method. Transition-state theory and quantum chemistry calculations with QCISD(T) were used to calculate the rate coefficients. Weak negative temperature dependence was observed with a measured activation energy of -(2.98 ± 0.12) kcal mol-1 and a calculated zero-point-corrected barrier energy of -3.29 kcal mol-1. At 298 K, the rate coefficient was measured to be (4.77 ± 0.95) × 10-11 cm3 s-1, which was in reasonable agreement with 2.2 × 10-11 cm3 s-1 from the theoretical calculation.

The reaction CH3CHI + O2 has been commonly employed in laboratories to produce a methyl-substituted Criegee intermediate CH3CHOO, but the detailed dynamics of this reaction remain unexplored. We carried out this reaction by irradiating a flowing mixture of CH3CHI2 (∼70 mTorr) and O2 (∼4 and 8 Torr) at 308 or 248 nm and observed infrared emission of the products with a step-scan Fourier-transform spectrometer. Upon irradiation at 248 nm with O2 ∼4 Torr, a Boltzmann distribution of CO (v ≤ 4, J ≤ 25) with average vibrational energy (12 ± 2) kJ mol-1 and of OH (v = 1, J ≤ 5.5) were observed and assigned to be produced from the decomposition of CH3C(O)OH* to form CO + CH3OH and OH + CH3CO, respectively. The observed broadband emission of CO2 was simulated with two vibrational distributions of average energies (42 ± 3) and (114 ± 6) kJ mol-1 and assigned to be produced from the decomposition of CH3C(O)OH* and (methyl dioxirane)*, respectively. The results upon irradiation of the sample at 308 nm are similar, likely indicating a small fraction of energy partition into these products and rapid thermalization of CH3CHI*. Compared with reaction CH2I + O2, the title reaction yielded products with much less internal excitation, consistent with the expectation that these observed products receive much less fraction of available energy upon fragmentation when an additional methyl moiety was present in the parent. The large-v component of CO observed in experiments of CH2I + O2 at 248 nm, produced from secondary reaction HCO + O2, was absent in this work because the corresponding secondary reaction CH3CO + O2 in decomposition of CH3CHOO* produces α-lactone + OH or H2CO + CO + OH.

It is known that by changing the concentration in an inert medium, it is possible to form clusters of various sizes of any substance by condensing them on a cold substrate from the gas phase. Traditionally, such systems are presented by molecular cryocrystals. This paper demonstrates the results of IR spectro­metric studies of cryovacuum condensates of ethanol mixture with nitrogen. The main task of this study is to explain the complex, most often, ambiguous behavior of thin films of ethanol cryovacuum conden­sates in the process of its co­condensation with nitrogen. For this purpose, vibrational spectroscopy of cryodeposited thin films of “ethanol in nitrogen” mixtures in various concentration ratios was performed. The objects of research are thin films of cryocondensates of ethanol mixture with inert gas (N2). The sam­ples were condensed at the temperature T = 16 K. The pressure of the gas phase of the mixture during cryocondensation was kept at P = 10­5 Torr. The range of ethanol concentrations in the mixtures varied from 3% to 90%. The spectral range of measurements was considered in 400­-4200 1/cm. It is assumed that the change in the concentration of ethanol in the mixture leads to the formation of various cluster compositions of ethanol molecules dissolved in an inert medium.

Since its inception in 1980s, differential or field asymmetric waveform ion mobility spectrometry (FAIMS) has been implemented at or near ambient gas pressure. We recently developed FAIMS at 15-30 Torr with mass spectrometry and utilized it to analyze amino acids, isomeric peptides, and protein conformers. The separations broadly mirrored those at atmospheric pressure, save for larger proteins that (as predicted) exhibited dipole alignment at ambient but not low pressure. Here we reduce the pressure down to 4.7 Torr, allowing normalized electric fields up to 543 Td-double the maximum in prior FAIMS or IMS studies of polyatomic ions. Despite the collisional heating to ∼1000 °C at the waveform peaks, the proteins of size from ubiquitin to albumin survived intact. The dissociation of macromolecules in FAIMS appears governed by the average ion temperature over the waveform cycle, unlike the isomerization controlled by the peak temperature. The global separation trends in this "superhot" regime extend those at moderately low pressures, with distinct conformers and no alignment as theorized. Although the scaling of the compensation voltage with the field fell below cubic at lower fields, the resolving power increased and the resolution of different proteins or charge states substantially improved.

Bonylip barb (Osteochilus vittatus Valenciennes, 1842) is a native fish of Indonesia's inland waters which has become a cultivated fish commodity. However, production tends to decrease due to high feed costs. The alternative feed types need to be found to anticipate the problem. Lemna perpusilla Torr is one of macrophytes plant which potentially used as an alternative feed due to high protein content. This study aims to evaluate the growth performance of fish fed with a combination of Lemna and commercial feed. As much of each 14 fishes were rearing in a 45x45x40 cm3 aquarium and fed for 84 days or 12 weeks. There are 5 combinations of feed, i.e feed A (100% commercial feed), B (75% commercial feed + 25% Lemna), C (50% commercial feed + 50% Lemna), D (25% commercial feed + 75% Lemna), and E (100% Lemna). The fishes were fed by commercial feed as much as 3% of the total fish, while administering Lemna at 30% of body weight. Growth performances were measured i.e standard and total length, absolute growth, specific growth rate and survival rate. The results showed that fish was able to growth using combination of commercial feed and Lemna. Data analysis was conducted descriptively that showed that fish fed by feed C (50% commercial feed + 50% Lemna) produced the highest length and weight, absolute growth and specific growth rate compared to other treatments. The highest survival rate was at fish fed by feed E (100% Lemna). The use of Lemna as an alternative feed is expected to reduce dependence on commercial feed.

The possibility of controlling the development rate of the incomplete staged of the discharge sliding over a solid dielectric surface is experimentally shown. Depending on the gas pressure and power supply voltage, the development rate of the incomplete stage of the discharge in air sliding over the solid dielectric surface is determined. It is shown that the discharge development rate varies from 1.4 × 106 to 7.8 × 106 cm/s in the pressure range from 10 to 60 Torr voltage from 4 to 12 kV. Emission of the second positive system of nitrogen dominates in the emission spectrum of the incomplete sliding discharge.

The effects of CaCl2 and abscisic acid (ABA) on the sprouts growth, γ-aminobutyric acid (GABA) and flavonoids accumulation in germinated Salicornia bigelovii Torr. were investigated under NaCl stress. Results showed that the content of GABA and flavonoids increased by 1.20 and 1.19 times under 5 mM CaCl2 treatment compared with the control group. The key enzymes including glutamate decarboxylase (GAD) and diamine oxidase (DAO), phenylalanine ammonolyses (PAL), cinnamicacid-4-hydroxylase (C4H) and 4-coumarate: CoA ligase (4CL) were increased significantly (p-1 NaCl, S. bigelovii had the higher content of GABA (398.26 mg100g-1) and flavonoids (36.90 mgg-1) than control group (pS. bigelovii.

We present a method for the fabrication of ultra-smooth (0.2 nm RMS), aluminum substrates through template stripping (TS). The method relies on the use of mica as a template in combination with thermal evaporation of Al at high (>10 nm/s) rates under vacuum (≤1 × 10-7 Torr). As a reactive metal, Al is usually not considered a viable option for TS off oxide templates. However, under these conditions, the adhesion between the Al film and mica is poor, enabling the removal of the template under water without any mica residue. We verify the absence of mica using atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. We establish the suitability of these films for surface forces measurements. Multiple-bean interferometry in transmission yields high quality fringes allowing for the measurement of force-distance curves. The adhesion the films to mica is significantly higher than the adhesion of thermally evaporated Al (0.9 nm RMS). Preliminary results suggest that the TS-Al surface displays a higher corrosion resistance. The fabrication method will enable important experiments on this widely used material.

The formation of β-Si3N4 for subsequent growth of AlGaN and GaN heterostructures of silicon wafers has been studied. It is established that the native oxide layer protects the silicon surface from the formation of amorphous silicon nitride when heating in an ammonia flow. Controlled formation of β-Si3N4 at partial ammonia pressures up to 3 × 10–5 Torr is demonstrated. This circumstance makes it possible to perform epitaxy of nitride films without cleaning the growth chamber from ammonia, which is usually required to remove the native silicon oxide by high-vacuum annealing.

In this article, the influences of outgassing and flashover on the performance of a novel multipacting cathode are numerically investigated by using particle in cell-Monte Carlo collision (PIC-MCC) method, including the conditions of weak, medium, and strong outgassing. The numerical results demonstrate that under the condition of weak outgassing (0.1 Torr), multipacting is hardly influenced by gas ionization. Multipacting dominates the entire physical process. Due to the further improved output current by additional electrons generated from ionization, the weak outgassing can help cathode performance enhancement. Under the condition of medium outgassing (1 Torr), gas ionization first boosts multipacting developing and then tends to suppress multipacting process. During the initial stage, multipacting dominates the entire physical process. When multipacting tends to saturate, gas ionization will dominate the whole physical process. The rapidly increased output current will finally decrease gap voltage and induce the diode breakdown. Under the condition of strong outgassing (1 atm), multipacting is suppressed by gas ionization from beginning to end. Gas ionization dominates the whole physical process all the time. The strong effect of ionization collision will finally induce streamer discharge and diode breakdown.

Zinc sulphide is a remarkable semiconductor material, with its highly demanded optical, electrical properties and its availability, it is used in the field of photovoltaic applications. The objectives are to investigate the effect of vacuum pressure on the glass substrate and the study different cluster models based on its crystal size. The ZnS thin films were fabricated using a thermal evaporator at the pressure of 10-5 Torr, 10-6 Torr, and 10-7 Torr. Four different size cluster models have been characterized theoretically. Each model was built based on the size of crystal structures, optimized to the lowest energy level, and evaluated as realistic clusters. The structural and optical properties of the thin films were studied using X-ray diffractometry, absorption, and photoluminescence spectroscopy respectively. Significant differences were observed in the crystal structure and optical properties of fabricated MoS2 thin films at different pressures.

A grid anode glow discharge is a promising source of plasma for absorbing electromagnetic radiation. This paper presents an experimental study of a large-area dc grid anode glow discharge in helium. The behavior of the helium discharge was studied at pressures in the range of 2–50 Torr and discharge voltages up to 1500 V. It was observed that the discharge completely covered the cathode surface at helium pressures of 2–25 Torr. For all pressures, voltage increases as current increases, which typical for anomalous glow discharge. The electron density in the post-anode plasma and attenuation of the microwave radiation by the plasma were measured using microwave diagnostic methods. It was found that the electron density and degree of helium ionization decrease with increasing helium pressure and increase with increasing discharge current. The electron density in the post-anode plasma is not high: ne is about 2 × 109–6 × 1010 cm–3, corresponding to a degree of ionization of about 10–7–10–6. It is shown that the maximum attenuation of 10-GHz microwave radiation is about 6% at a helium pressure of 2 Torr.

It is well known that the environmental radiation surrounding us consists of various types of radiation that could be dangerous to human health, causes air pollution and also has importance in industry and medicine. There are different types of gamma spectrometry and radiation protection technologies are available. Even though these technologies have been used for several decades; there is a need to improve the sensitivity and selectivity for these detectors. The Multilayer PCB technology based Nanodosimeter was designed to capture positive ions produced by the interaction of ionizing radiation with low pressure gas medium. In order to confirm the signal, the present signal captured under methane medium at 1 to 10 Torr pressure. The indigenously fabricated 3D positive ion detector of thickness 3.483 mm with optimized cathode was using the same Nanodosimeter experimental setup using the Co-60 source. To conform the performance of the 3D positive ion detector as gamma spectrometry and Radiation protection.

Coatings by physical vapor deposition (PVD) have become highly relevant due to their wide range of applications and the rapid rate of coating formation. In this work, AISI steel 1045 was coated with two layers, Ni and Co using the PVD technique. Each coating was deposited with a thickness of 1 μm. After applying the coatings, a post-treatment was applied in an AC plasma reactor using a boron nitride blank in an Ar atmosphere at a pressure of 3 Torr, 0.3 A, and 460 V at 4, 8, and 12h. The post-treatment was characterized by optical emission spectroscopy (OES) in a range of 200-1100 nm. The main species observed by OES were Ar+, N2, N2+, and B+. The coatings on 1045 steel and posttreatment were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Also, were subjected to tribological tests to analyze wear resistance, using the Pin-on-Disk technique. The coatings on steel 1045 present remarkably better wear properties than the uncoated 1045 steel, being the sample post-treated at 4h that showed a lower wear rate.

α-Ga2O3 has the largest bandgap (~5.3 eV) among the five polymorphs of Ga2O3 and is a promising candidate for high power electronic and optoelectronic devices. To fabricate various device structures, it is important to establish an effective dry etch process which can provide practical etch rate, smooth surface morphology and low ion-induced damage. Here, the etch characteristics of α-Ga2O3 epitaxy film were examined in two fluorine-based (CF4/Ar and SF6/Ar) inductively coupled plasmas. Under the same source power, rf chuck power and process pressure, an Ar-rich composition of CF4/Ar and an SF6-rich composition of SF6/Ar produced the highest etch rates. Monotonic increase in the etch rate was observed as the source power and rf chuck power increased in the 2CF4/13Ar discharges, and a maximum etch rate of ~855 A/min was obtained at a 500 W source power, 250 W rf chuck power, and 2 mTorr pressure. A smooth surface morphology with normalized roughness of less than ~1.38 was achieved in the 2CF4/13Ar and 13SF6/2Ar discharges under most of the conditions examined. The features etched into the α-Ga2O3 layer using a 2CF4/ 13Ar discharge with 2 mTorr pressure showed good anisotropy with a vertical sidewall profile. (Received December 15, 2020; Accepted January 14, 2021)

In this work, we reported improved resistive switching (RS) of SnO2-based resistive random access memory (RRAM) devices according to the post microwave treatment (MWT), working pressures (WP), and the electrode. As a result, as the deposition pressure increased, the operational current of all the devices became commonly lower, and when comparing SnO2 RRAM devices, the optimal RS characteristics are obtained from the sample with Ag top-electrode deposited at WP of 10 mTorr and after the MWT process. The filament was also investigated, for the sample deposited at 5 mTorr, the diameter of the filament was wider in both the high resistive state and the low resistive state as a result of increasing the number of cycles. As a result, the larger the diameter of the filament, the longer the time for the filament formation and rupture was found.

A portable self-flow filtration and separation platform was designed using soft lithography to create a polydimethylsiloxane (PDMS) microfluidic channel cover combined with a matching acrylic substrate. The separation zone was filled with microbeads of appropriate sizes to achieve universal filtration and separation. This simple structure requires only 20 μl of the sample for filtration separation. A vacuum of 760 torr is applied to the porous PDMS cover to drive the sample during testing. The average time required for a 20 μl sample of blood to pass through the separation zone is about 56 s, while the filling time for the detection zone of volume 6 μl is about 319 s. When the hematocrit of the blood sample is about 20-25%, the separation efficiency is 99.98%. Further, the separation efficiency of fat globules from raw milk is close to 100%, whereas almost all impurities are filtered out from juice and stool samples. It is also observed that E. coli in the stool can pass from the separation to detection zone at a maximum rate of about 81.21%, with an average of about 68.18%.

Rate coefficients, k, for the gas-phase Cl + Furan-2,5-dione (C4H2O3, maleic anhydride) reaction were measured over the 15–500 torr (He and N2 bath gas) pressure range at temperatures between 283 and 323 K. Kinetic measurements were performed using pulsed laser photolysis (PLP) to produce Cl atoms and atomic resonance fluorescence (RF) to monitor the Cl atom temporal profile. Complementary relative rate (RR) measurements were performed at 296 K and 620 torr pressure (syn. air) and found to be in good agreement with the absolute measurements. A Troe-type fall-off fit of the temperature and pressure dependence yielded the following rate coefficient parameters: ko(T) = (9.4 ± 0.5) × 10−29 (T/298)−6.3 cm6 molecule−2 s−1, k∞(T) = (3.4 ± 0.5) × 10−11 (T/298)−1.4 cm3 molecule−1 s−1. The formation of a Cl·C4H2O3 adduct intermediate was deduced from the Cl atom temporal profiles and an equilibrium constant, KP(T), for the Cl + C4H2O3 ↔ Cl·C4H2O3 reaction was determined. A third-law analysis yielded ΔH = −15.7 ± 0.4 kcal mol−1 with ΔS = −25.1 cal K−1 mol−1, where ΔS was derived from theoretical calculations at the B3LYP/6-311G(2d,p,d) level. In addition, the rate coefficient for the Cl·C4H2O3 + O2 reaction at 296 K was measured to be (2.83 ± 0.16) × 10−12 cm3 molecule−1 s−1, where the quoted uncertainty is the 2σ fit precision. Stable end-product molar yields of (83 ± 7), (188 ± 10), and (65 ± 10)% were measured for CO, CO2, and HC(O)Cl, respectively, in an air bath gas. An atmospheric degradation mechanism for C4H2O3 is proposed based on the observed product yields and theoretical calculations of ring-opening pathways and activation barrier energies at the CBS-QB3 level of theory.

This work has demonstrated that the single source precursor [nBu3Sn(TenBu)], bearing n-butyl groups and containing the necessary 1 : 1 Sn : Te ratio, facilitates growth of continuous, stoichiometric SnTe thin films. This single source CVD precursor allows film growth at significantly lower temperatures (355–434 °C at 0.01–0.05 Torr) than required for CVD from SnTe powder. This could be advantageous for controlling the surface states in topological insulators. The temperature-dependent thermoelectric performance of these films has been determined, revealing them to be p-type semiconductors with peak Seebeck coefficient and power factor values of 78 μV K−1 and 8.3 μW K−2 cm-1, respectively, at 615 K; comparing favourably with data from bulk SnTe. Further, we have demonstrated that the precursor facilitates area selective growth of SnTe onto the TiN regions of SiO2/TiN patterned substrates, which is expected to be beneficial for the fabrication of micro-thermoelectric generators.

The gas-jet method of the deposition of diamond-like structures using super-high-frequency (SHF) discharge for activating gases is considered. Direct statistical simulation is applied to analyze the gasdynamic processes occurring in the conditions of the gas-jet deposition of diamond structures. An activated gas flow in a nozzle is investigated and a considerable influence of the processes in the compressed layer formed near the substrate on the rate of synthesis of diamond structures is established. The regimes of flow of mixture components activated in the discharge chamber toward the substrate are determined and a considerable deceleration of heavy components in the compressed layer is found to exist. It is shown that with increase in the pressure in the deposition chamber from 10 to 80 Torr the crystal growth rate increases fourfold at the expense of an increase in the specific flux of the activated components toward the substrate.

The kinetics for the reactions of CH2OO and syn-CH3CHOO with acrolein, a typical unsaturated aldehyde in the atmosphere, were studied in a flash photolysis flow reactor using the OH laser-induced fluorescence (LIF) method. The bimolecular reaction rate coefficients were measured at temperatures ranging from 281 to 318 K, and pressures ranging from 5 to 200 Torr. No obvious dependence of the rate coefficients on pressure was observed under the current experimental conditions. Both reactions exhibit negative temperature-dependence, with an activation energy of (−1.70 ± 0.19) and (−1.47 ± 0.24) kcal mol−1 for CH2OO and syn-CH3CHOO reacting with acrolein, derived from the Arrhenius equation. At 298 K, the measured rate coefficients for CH2OO/syn-CH3CHOO + acrolein reactions are (1.63 ± 0.19) × 10−12 cm3 s−1 and (1.17 ± 0.16) × 10−13 cm3 s−1, respectively. The rate coefficient of the former reaction is in reasonable agreement with a recent theoretical result.

In the past studies have shown that the addition of Ge and Sn into Si lattice to form SiGeSn enhances its carrier mobility and band-gap properties. Conventionally SiGeSn epitaxial films are grown using Ultra-High Vacuum (UHV) conditions with pressures ranging from 10-8 torr to 10-10 torr which makes high volume manufacturing very expensive. On the contrary, the use of low-pressure CVD processes (vacuum levels of 10-2 torr to 10-4 torr) is economically more viable and yields faster deposition of SiGeSn films. This study outlines the use of a cost-effective Plasma Enhanced Chemical Vapor Deposition (PECVD) reactor to study the impact of substrate temperature and substrate type on the growth and properties of polycrystalline SiGeSn films. The onset of polycrystallinity in the films is attributed to the oxygen-rich PECVD chamber conditions explained using the Volmer-Weber (3D island) mechanism. The properties of the films were characterized using varied techniques to understand the impact of the substrate on film composition, thickness, crystallinity, and strain.

The photovoltaic characteristics of high-quality Bi2Se3 grown on black phosphorus (BP) heterostructure via modulated elemental reactants (MER, annealed in situ at 220 °C for 20 min in a vacuum of 10−9 torr) growth of a Bi2Se3 topological insulator (TI) film on an exfoliated BP two-dimensional (2D) nanosheet was investigated. The Bi2Se3/BP heterostructure showed high-efficiency photocharacteristics (responsivity: 12.1 mA W−1, rise time: 1.3 ms, and broadband detection range: λ = 350–950 nm), which are attributed to the narrow band gap of the bulk state and mobility of the Dirac surface state. Moreover, the Bi2Se3/BP heterostructure can produce heterojunctions in the sharp interface region, thereby resulting in the contribution of a strong built-in electric field and photoexcited carrier tunnel through the interactive interfacial region at the TI/2D heterostructure based on the photovoltaic device. This work demonstrates practical photovoltaic applications, as well as the integration of such TIs on 2D materials, which can offer great opportunities for the realization of next-generation optoelectronic devices.

The decomposition kinetics of 2-ethylhexyl nitrate behind incident shock waves in a diaphragmless shock tube facility were studied with a laser schlieren densitometry diagnostic at temperatures from 670 to 940 K and pressures of 35, 59, and 118 Torr. Measured density gradients informed improvements to the decomposition mechanism of 2-ethylhexyl nitrate. In particular, the analysis revealed important 3-heptyl radical chemistry. The measured and predicted rate constants are near the high-pressure limit.

The kinetics of the gas phase reaction of the Criegee intermediate CH2OO with SO2 have been studied as a function of temperature in the range 223–344 K at 85 Torr using flash photolysis of CH2I2/O2/SO2/N2 mixtures at 248 nm coupled to time-resolved broadband UV absorption spectroscopy. Measurements were performed under pseudo-first-order conditions with respect to SO2, revealing a negative temperature dependence. Analysis of experimental results using the Master Equation Solver for Multi-Energy well Reactions (MESMER) indicates that the observed temperature dependence, combined with the reported lack of a pressure dependence in the range 1.5–760 Torr, can be described by a reaction mechanism consisting of the formation of a pre-reaction complex leading to a cyclic secondary ozonide which subsequently decomposes to produce HCHO + SO3. The temperature dependence can be characterised by kCH2OO+SO2 = (3.72 ± 0.13) × 10−11 (T/298)(−2.05±0.38) cm3 molecule−1 s−1. The observed negative temperature dependence for the title reaction in conjunction with the decrease in water dimer (the main competitor for the Criegee intermediate) concentration at lower temperatures means that Criegee intermediate chemistry can play an enhanced role in SO2 oxidation in the atmosphere at lower temperatures.

We have developed and tested two-photon excited fragment spectroscopy (TPEFS) for detecting HNO3 in pulsed laser photolysis kinetic experiments. Dispersed (220–330 nm) and time-dependent emission at (310 ± 5) nm following the 193 nm excitation of HNO3 in N2, air and He was recorded and analysed to characterise the OH(A2Σ) and NO(A2Σ+) electronic excited states involved. The limit of detection for HNO3 using TPEFS was ∼5 × 109 molecule cm−3 (at 60 torr N2 and 180 μs integration time). Detection of HNO3 using the emission at (310 ± 5 nm) was orders of magnitude more sensitive than detection of NO and NO2, especially in the presence of O2 which quenches NO(A2Σ+) more efficiently than OH(A2Σ). While H2O2 (and possibly HO2) could also be detected by 193 nm TPEFS, the relative sensitivity (compared to HNO3) was very low. The viability of real-time TPEFS detection of HNO3 using emission at (310 ± 5) nm was demonstrated by monitoring HNO3 formation in the reaction of OH + NO2 and deriving the rate coefficient, k2. The value of k2 obtained at 293 K and pressures of 50–200 torr is entirely consistent with that obtained by simultaneously measuring the OH decay and is in very good agreement with the most recent literature values.

In this study, optical, morphological and structural properties of inverted organic solar cell structure such as the electron transport layer and hole transport layer was examined. Molybdenum trioxide (MoO3) was used as a hole transport layer (HTL) in an inverted structure while zinc oxide (ZnO) used as an electron transport layer (ETL) in the same structure. Firstly, the chemical cleaning of glass was done. After, 0.5 g zinc acetate dihydrate was dissolved in 6.38 ml ethanol and zinc oxide (ZnO) solution was obtained. Zinc oxide (ZnO) solution was filtered using an 0.45 ɥm PVDF filter. Then, ZnO solution was coated on glass surfaces by spin coating at 2500 rpm for 50 sec followed by annealing at 150 °C for 10 min on a hot plate in ambient. Secondly, 10 nm thick molybdenum trioxide (MoO3) was coated on the glass surfaces using thermal evaporation at a pressure of 5 × 10−7 Torr and an evaporation rate of 1 A/sec in the glove box system. XRD, SEM, AFM, thickness and absorption measurements of these thin films coated on glass surfaces were performed. In the next stage, fabrication and characterization of ITO/ZnO/P3HT:PCBM/MoO3/Al inverted organic solar cells structures will be performed using these films.

In mass spectrometry (MS), a major loss of ions can readily occur during their transfer from atmospheric pressure to a lower pressure, which limits performance. Here, we report an ion funnel that can be used to effectively focus ions at ambient pressure (∼777 Torr) to significantly enhance performance in electrospray ionization (ESI) MS. For seven singly charged test ions (m/z 124-1131), the ambient pressure ion funnel (APIF) is demonstrated to improve ion abundances, sensitivity, and detection limits by up to factors of ∼17, ∼16, and ∼3, respectively, compared to the operation of conventional ESI-MS. Simulated ion trajectories were used to rationalize the enhanced performance of the APIF, which is attributed primarily to using a relatively high RF field amplitude to radially confine ions, a high DC field, and a wide exit ring electrode. The effective focusing of ions at ambient pressures should be beneficial in the future for improving the performance of (i) additional methods that ionize molecules at atmospheric pressure, (ii) ambient pressure ion mobility-based instruments, and (iii) high flow rate liquid chromatography mass spectrometry platforms.

The OH + NO_2 reaction is a critically important process for radical chain termination in the atm. with a major impact on the ozone budgets of the troposphere and stratosphere. Rate consts. for the reaction of OH + NO_2 + → products have been measured under conditions relevant to the upper troposphere/lower stratosphere with a Pulsed Laser Photolysis - Pulsed Laser Induced Fluorescence technique augmented by in situ optical spectroscopy for quantification of [NO_2]. The expts. are carried out over the temp. range of 230K - 330K and the pressure range 40-800 Torr of air and N_2. The reaction was studied under pseudo first-order conditions, monitoring the decay of OH in the presence of a large excess of NO_2. The obsd. pressure and temp. dependences are analyzed to quantify the falloff behavior and to derive parameters for Troe falloff expressions. The atm. implications are discussed.

The design of a source of a seeded supersonic beam of alkali halide molecules or other vaporized solids is described. At a carrier gas (hydrogen or helium) stagnation pressure of 0.5–5 atm, a stagnation temperature of 1000 K, and a partial seed species pressure of 10–2 Torr, the intensity of the salt beam was 1014 sr–1 s–1 and the energy of molecules in the beam varied from 5.5 to 7.5 eV for a mixture with helium and from 7.5 to 15.5 eV for a mixture with hydrogen. The modular design of the source provides the easy replacement of its functional units.

Plasma was generated in the focal region of a multikilowatt, 4.7-GHz continuous-wave (CW) microwave beam far removed from the walls of the vacuum chamber, minimizing the nonideal effects associated with plasma–wall and beam–wall interactions. Experiments were conducted with gas mixtures of argon, nitrogen, and oxygen at gas pressures ranging from 100 to 200 mtorr. Three types of discharges were observed during these experiments: unstable, quasi-stable, and stable discharges. It was determined that the stability of the discharges could be controlled through adjustments of the gas composition, gas pressure, and power of the microwave beam. This article reports on the operational conditions in which stable discharges were achieved and the general behavior of these discharges as the control parameters were varied.

Oxidation of monometallic Pd and bimetallic Pd3Au alloy surfaces are observed by in situ ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) at an elevated pressure (100 mTorr O2 ambient). I...

Metal salt soaking–torrefaction conversion technology was investigated. It was found that AlCl3 pretreatment of pubescens favored observably the yield of liquid and small-molecular products in torrefaction via changing the composition and structure of the raw material. The maximum conversion of pretreated samples, washed (PSW) and Yliquid were 15.5 and 10.8 wt % (with 0.26 wt % monosaccharides, 0.26 wt % carboxylic acids, 0.38 wt % furan compounds, and 1.28 wt % phenols), where 20.4 wt % hemicellulose, 22.9 wt % cellulose, and 5.7 wt % lignin were converted, respectively. However, for pretreated samples (PS), the maximum conversion and Yliquid reached 44.2 and 32.1 wt %, respectively, along with 96.0 wt % hemicellulose and 31.8 wt % cellulose converted, yielding 2.39 wt % monosaccharides, 5.14 wt % carboxylic acids, 2.60 wt % furan compounds and 10.52 wt % phenols, indicating obvious catalytic effects of residual AlCl3 on the decomposition of the three major components in torrefaction. Two-dimensional HSQC and electrospray ionization mass spectrometry (ESI-MS) characterizations further confirmed the dominant formation of oligomers derived from holocellulose, lignin, and cross-linkage involving the lignin–carbohydrate complex, indicating that the catalytic thermal cleavage of β-O-4, C-O-C, β-β, 5–5, 4-O-5, Cα–Cβ, and α-O-4 linkages by aluminum species in the samples benefited the yield of liquid as well as monophenols.

The resistive switching (RS) of metal/nanocomposite/metal (M/NC/M) memristive structures based on the (Co40Fe40B20)x(LiNbO3)100 – x nanocomposite with a ferromagnetic alloy content х ≈ 8–20 at % is studied. The structures were synthesized by ion beam sputtering with an increased oxygen content (≈2 × 10–5 Torr) at the initial stage of NC growth, as a result of which a thin (15–18 nm) LiNbO3 layer appears at the bottom electrode. It is found that the structures have multilevel character of RS (at least four levels) with the retention time of the emerging resistive states of more than 104 s and demonstrate the possibility of the resistive states change according to biosimilar rules such as spike-timing-dependent plasticity (STDP). Unusual kinetics of RS to the low-resistance state was found: RS occurs with a delay of about 70 μs; the RS time in this case reaches ~5 ns, and the energy consumption for switching is ~1 nJ.

In this paper, a low activation of ferritic-austentic steel was studied when it was exposed with plasma. The experiment was carried out on a plasma focus device with energy of 1.9 kJ, with a pressure of 2.5 torr of deuterium. AFM analysis shows that cracks up to 2 microns and holes from 81 to 281 nm are found on steel surfaces. The mechanism of the occurrence of erosion of low-activation ferritic-austentic steel is also indicated. It is established that the mechanism of erosion depends on the momentum.

The holy grail of group-IV light emission would be electrically pumped lasing at Room Temperature (RT). In CEA-LETI, the performance of p-i-n light emitting diodes is limited by the use of in-situ doped Ge layers beneath and above the active layer stack [1]. To overcome Sn segregation during the growth of the top electrode and, in thick GeSn/Ge stacks, avoid plastic relaxation, it would be ideal to switch over to in-situ doped GeSn grown at temperatures similar to that of the active region. We have therefore explored the in-situ boron and phosphorous doping of GeSn on Ge strain relaxed buffers with Ge2H6+SnCl4+ B2H6 and Ge2H6+SnCl4+PH3 chemistries. Growth pressure, temperature, F(Ge2H6)/F(H2) and F(SnCl4)/F(H2) Mass Flow Ratio (MFR) were 100 Torr, 349 °C, 7.92x10-4 and 4.78x10-5. X-Ray Diffraction (XRD) measurements were conducted to gain access to the GeSn composition and layer thickness, as shown in Fig. 1 and Fig. 2. As the GeSn peak position was determined by the Sn content and also the B or P substitutional concentrations, the actual layer composition could not be unambiguously determined. Therefore, the Sn content in the following is an apparent Sn content. Thickness fringes outline the high GeSn crystalline quality. As the F(B2H6)/F(Ge2H6) or the F(PH3)/2 F(Ge2H6) MFRs increased, the apparent Sn content stayed at first roughly around 6.5 %, as shown in Fig. 3. This value was the same for i-GeSn, GeSn:B and GeSn:P, in contrast to previous literature findings [2]. As the MFRs reached the highest values, the apparent Sn content reduced significantly for GeSn:B (from 6.5 % down to 4.6 %) and less significantly GeSn:P (from 6.6 % down to 5.6 %). The significantly smaller size of B compared to P (aB = 3.852 Å aP = 5.014 Å) reduced the compressive strain in GeSn:B 2.8 times more than in GeSn:P for the same dopant concentrations, explaining the more pronounced effect. We quantified the substitutional B and P incorporation by assuming that the Sn content was not impacted by B or P incorporation. The estimated B and P substitutional concentrations then increased from 2.8x1019 cm-3 up to 3.8x1020 cm-3 and from 2.5x1019 cm-3 up to 5.4x1020 cm-3 (highest four MFRs for GeSn:B and GeSn:P), shown in Fig. 4. Those values are close indeed to the highest substitutional B or P concentrations obtained in Ge:B or Ge:P layers grown at 350°C, 100 Torr with Ge2H6: 4.8x1020 cm-3 [3] and 4.1x1020 cm-3 [4], respectively. We determined elemental growth rates by multiplying the GR by the Ge or apparent Sn content to have a more detailed look at the growth mechanics (Fig. 5). The introduction of SnCl4 catalyzed the growth rate of GeSn compared to that of pure Ge, in line with the literature [4]. As the F(B2H6)/F(Ge2H6) or the F(PH3)/2F(Ge2H6) MFR increased, the Sn GR component stayed constant at around 2.5 nm min.-1. Meanwhile, the Ge GR component was constant at around 37 nm min.-1 for lower MFRs. For high dopant flows, the Ge GR component increased significantly for GeSn:B and reached 48 nm min.-1. The increase was less significant for GeSn:P, with at most 40 nm min.-1. This is to our knowledge, the first time an increase of the GeSn:P GR is reported for high dopant flows. Similar increases were found for Ge:P and Ge:B grown at 350°C, however [3-4]. The constant Sn GR component and the increase of the Ge GR component at high MFRs are likely due to an increased incorporation of Ge thanks to B and P opening surface sites (Indeed, the Ge GR component is surface rate limited, while the Sn GR component is reaction rate limited [5]). A cross-hatch along was found by Atomic Force Microscopy for all layers, which were otherwise smooth and featureless, as shown in Fig. 6 top for GeSn:B and Fig. 6 bottom for GeSn:P. The only exceptions were the GeSn:B samples grown at the three highest MFRs. There were then some islands, which were likely due to B and/or Sn surface segregation. Other studies will be performed to gain access to the Sn, P and B contents. [1] M. Bertrand et al., 2018 IEEE International Conference on Group-IV Photonics, pp. 45-46. [2] J. Margetis et al., Mater. Sci. Semicond. Process. 70, 38 (2017). [3] J.M. Hartmann et al., ECS PRIME 2020 Meeting Abstract ID 138196, Symposium G03. [4] J. Aubin et al., ECS J. Solid State Sci. Technol. 6, 1 (2017). [5] J. Margetis et al., J. Vac. Sci. Technol. A 37, 021508 (2019). Figure 1

Theoretical and experimental studies of the synthesis of graphene with the introduction of nitrogen into a jet of helium plasma generated by a direct-current plasma torch with a power of to 40 kW at a pressure of 350 Torr have been performed. A propane–butane mixture was used as a source of carbon. As found by scanning microscopy, Raman scattering, and synchronous thermal analysis, the morphology of the synthesis products changed from graphene flakes to carbon nanotubes upon the addition of nitrogen in a ratio of 1 : 1.22 to the jet of helium plasma. The numerical modeling of the process showed that cyanopolyyne molecules, HC9N and HC11N, containing many carbon atoms appeared instead of C60 and C80 in the jets of helium upon the addition of nitrogen.

Propagation velocity of a subthreshold microwave discharge in air and carbon dioxide is measured at various gas pressures and intensities of microwave radiation. At air pressures of 200, 390, and 738 Torr and carbon dioxide pressures of 390 and 750 Torr, the propagation velocity of the head part of the self-non-self-sustained discharge closely follows a quadratic power law as a function of microwave-beam intensity in the range from 4 to 16 kW/cm2, while decreasing directly proportional to the initial gas density. In the process, the discharge propagation velocities in carbon dioxide are twice lower that those in air at equal intensities of the microwave radiation. The temperature in the head part of the discharge in air reaches 3.5–5.5 kK, while that in carbon dioxide reaches 9–15 kK.

This paper presents a study of a CH4-CO2 plasma-reforming process carried out in a high power density (5-50 W/cm3), using toroidal transformer-coupled plasma, and operated at low pressure (0.2-0.7 Torr). Using the intermediate between a thermal and nonthermal plasma (electron density, ne ≈ 3 × 1012 cm-3 and a maximum gas temperature of ∼4000-6000 K along the center line), the low-pressure study provides a unique set of conditions to investigate reaction mechanisms, where three-body reactions can be ignored. Reactive species in the plasma were identified by optical emission spectroscopy. End products of the reforming process were measured by mass spectrometry. Quite high conversions of CO2 and CH4 were found (90%), with selectivities for CO and H2 of 80% at 300 sccm feed gas flow rate in a 0.5 Torr plasma, with a mole ratio CO2-CH4 of 1:1. A detailed reaction mechanism is presented, taking into account the combined detection of reactive intermediates in the plasma (H, O, CH, and C2) and stable product downstream.

Paschen curves were studied using different cathode materials such as magnesium, zinc, and carbon graphite by discharge in argon gas of a pressure range between 0.08 and 3 Torr using a parallel plates configuration. The first and second Townsend coefficients (α and γ, respectively) and the ionization efficiency (η) of different cathode materials were deduced from Paschen curves as a function of the reduced field (E/P). The minimum breakdown voltage was found to be about 242 V for Mg material, which has the lowest work function, while carbon graphite has a higher breakdown voltage of 283 V due to its higher work function. The second coefficient γ was increased as a function of E/P and has higher values for materials of lower work functions, and a similar trend of γ is obtained as a function of the ion mean energy. On the other hand, the first coefficient α has a reverse behavior with both E/P and the work function of the cathode materials compared with the second coefficient. The ionization efficiency of the three cathode materials is identical, as η depends only on the gas properties and not the cathode material. η has a maximum value of about 0.025 V−1 for an E/P of about 185 Vcm−1Torr−1, corresponding to the maximum ionizing ability of electrons. The validation of the breakdown results has been confirmed by conferring with other published experimental measurements.

The kinetics of the gas phase reactions of the Criegee intermediate CH2OO with O3 and IO have been studied at 296 K and 300 Torr through simultaneous measurements of CH2OO, the CH2OO precursor (CH2...

Plasma discharges are sustained in the focus of a continuous, high-power microwave beam. The experimental design minimizes interactions between the chamber walls and both the microwave beam and the resulting discharges so as to approximate free-space conditions. Discharges were generated by a multikilowatt, 4.7-GHz CW microwave beam at pressures ranging from 100 to 200 mtorr. The CW source enabled the evolution of the plasma-beam system to be observed over time scales ranging from seconds to hours. A variety of discharge behaviors are observed depending on the conditions (power, pressure, and gas composition) within the chamber. The observed discharges can be classified into three discharge modes: unstable, stable, and quasi-stable. Here, we present observations and a preliminary analysis of the various discharge modes observed in the experiment.