Radical Density Research Articles

Optical and mass spectrometric measurements of dissociation in low frequency, high density, remote source O2/Ar and NF3/Ar plasmas

Remote plasma sources are widely used in applications such as chamber cleaning and flowable chemical vapor deposition. In these processes, it is desirable that the dissociation rate of feed gases be as high as possible and stable. Here, the authors present results on radical densities and gas dissociation fractions for a 400 kHz toroidal transformer-coupled plasma source (MKS Instruments), operating at a power density of 5–50 W/cm3 with feed gas mixtures of O2 or NF3 in Ar and pressures of 0.4 or 2.0 Torr. Radical densities and feed gas dissociation percentages in the plasma were measured by optical emission spectroscopy combined with Ar actinometry. In the plasma, O2 was about 60% dissociated in dilute O2 mixtures (10%–20%). Dissociation decreased with the increasing addition of O2, dropping to 10% dissociation for 90% O2 in the feed gas. NF3 was >95% dissociated for all NF3/Ar mixtures. Little or no dependence on the flow rate was found. Plasma products flow into an anodized Al downstream chamber that is probed by vacuum ultraviolet (VUV) absorption spectroscopy and line-of-sight molecular beam mass spectrometry. In the downstream chamber, O recombined on the walls to form O2 (detected by VUV O2 absorption). The measured downstream O/O2 ratio was a strongly increasing function of an increasing flow rate reproduced by a downstream global model with O wall recombination probability of γO between 0.001 and 0.002. NF3 does not reform in the downstream chamber, as verified by VUV absorption and mass spectrometry. No NF or NF2 was detected, and F mostly recombined to form F2 at the back of the downstream chamber, along with N2. The F2, F, and N2 product absolute number densities were consistent with the 3:1 F:N mass balance of the NF3 feed gas.

Development of a probe-type optical absorption spectroscopic system for spatially resolved CF2 density measurement in inductively coupled C4F8/Ar plasmas.

A spatially resolvable optical probe is developed for the measurement of absolute CF2 radical density in inductively coupled plasmas using the broadband ultraviolet absorption spectroscopic method. The probe-type system is implemented inside a low-pressure inductively coupled plasma chamber and is built using a series of optical fibers, feedthroughs, collimators, and an ultraviolet light emitting diode. Using the CF2 A(0, v2', 0) ← X(0, 0, 0) absorption spectra, the spatial profile of CF2 density in the remote region of an inductively coupled C4F8/Ar plasma is investigated. The CF2 density is found to decrease from 4.06 × 1013 cm-3, around the chamber center, to 2.66 × 1013 cm-3, near the chamber wall. The spatial profile of the measured CF2 density, layer thickness, and composition of deposited films are compared. Plasma properties such as electron temperature and ion density are also discussed.

Bifunctional graphene oxide nanosheets for interfacially robust polymer actuators with instant solvent-induced self-folding

Polymers are ideal for deformation-induced actuating in soft robotics due to their great physical flexibility. However, creating polymer films with tunable deformation and a sufficient binding strength between layers is a big challenge. In this work, graphene oxide nanosheets with tunable radical contents are prepared for in-situ polymerization and grafting of polymers to achieve chemically crosslinked composites. The radical density and loading of nanosheets control the crosslinking density of a polymer film, which tunes its solvent-absorbing (swelling) capacity. A solvent-responsive polymer actuator that folds and grips an object can be fabricated by assembling two films with different degrees of swelling. Thermal annealing of two polymer strips at 100 °C significantly improves the fracture strength from 60 KPa to 380 KPa and the fracture strain from 70% to 170%. The results of this work demonstrate that radical-engineered graphene oxide nanosheets can be used to fabricate smart polymers with tunable bending performance and super interfacial binding strength for applications such as soft robotics.

Mechanistic Study of the Electrochemical Pathways for Methyl Surface Intermediates during Organic Oxidations

The electrochemical activation of methane has been an area of significant discussion and growing research interest in recent years as society looks for more environmentally benign processes to synthetically create complex organic molecules – preferably under mild conditions. This requires an electrochemical cascade that starts with easy to obtain small molecules (e.g. methane, ethane, acetic acid) and preferably ends with intermediate-length (4-10 carbon) paraffins and olefins – not just the formation of single-carbon oxygenates. Forming longer-chain molecules requires the surface stabilization of the reaction intermediates that drive C-C bond formation, such as methyl (CH3) and methylene (CH2) radicals. Therefore, understanding the behavior of these surface species during methane electrochemical oxidation is extremely important to synthesize multi-carbon species. Unfortunately, for methane activation, very high electrode potentials are often required to break the C-H bond, and the resulting electrode potential is so high that methane and nearly all of its reaction intermediates are completely oxidized to CO2. Because of this, not only is the faradaic efficiency low on many existing catalysts, but very little is known about the behavior of the surface intermediates that are formed, such as methyl (CH3) and methylene (CH2) radicals. Because of the difficulty in creating surface-stable radicals at the high potentials needed for methane activation, most of the experimental work and DFT calculations work that have been done regarding CH4 activation and upgrading has focused on understanding how the C-H bond breaks and how catalyst composition influences the location and orientation of the resulting methyl radical (CH3). Though this understanding is important and investment in this area needs to be continued for the foreseeable future, it will not answer other fundamental and practical questions about what happens after the C-H bond is broken on the catalyst surface – including understanding the variables that control C-C coupling to create multi-carbon paraffins, olefins or alcohols as well as selectivity. In this work, we have taken the unique approach of creating these radicals from a proxy reaction instead – acetic acid electrochemical oxidation [1]. The first step in the reaction of acetic acid is breaking the C-C bond, forming CO2 and a high surface density of CH3 radicals (likely more than methane activation due to the much higher concentration in the aqueous electrolyte and lower potential needed for activation). In this work, a series of electrochemical and isotope labeling experiments were done in order to understand the reactivity and reaction pathways of the CH3 radicals. A series of hydrocarbons and oxygenates such as ethane, ethylene, methanol and ethanol were observed. A comprehensive mechanism for the reaction of CH3 radicals on Pt electrodes will be proposed. These results enable a more fundamental understanding of how the CH3 radical behaves under oxidizing conditions, which can provide insight for reactor designs that enable methane electrochemical upgrading. Reference: Peng, X.; Omasta, T.J.; Xinyi, Z.; Mustain, W.E. Electrochemical Pathways for Electrochemical Oxidation of Acetic Acid. ECS Trans. 2018, 85, 29–34.

Process Development of Radical Based Dry Clean for Advanced 3D NAND Fabrication

As semiconductor device scaling marching toward sub-5 nm logic, 128+ layers 3D NAND, and advanced 1x nm DRAM technology nodes, wafer surface cleaning and residue removal in nanoscale, high aspect ratio structures become increasingly critical. Dry clean technologies are developed as alternatives for traditional wet clean applications with significant advantages in process extendibility and environmental friendliness. Furthermore, in comparison with gas only processes, radicals are considered as attractive precursors for dry clean applications due to their high reactivity en route to a high cleaning efficiency. In this work we report a novel inductively coupled remote plasma source design for radical based dry clean applications. The inductively couple plasma (ICP) source yields a high gas dissociation efficiency and a high radical density. Plasma potential and electron temperature are minimized with a unique grounded Faraday shield design and can be further suppressed with a pulsed plasma operation. Ions and electrons generated in the plasma are effectively filtered by charge separation grids, thus only leaving high flux radicals to impinge onto the wafer surface. Different radical chemistries are developed for selective removal of different dielectric, metal, and semiconductor materials, specifically for efficient cleaning inside nanoscale and high aspect ratio structures in advanced semiconductor devices. Here we report the following applications tailored toward 3D NAND manufacturing. Pre-epitaxial deposition clean in high-aspect-ratio channel holes: The requirements are to remove SiOx-like residues and damaged silicon layer at the bottom of high-aspect-ratio channel holes without damage to the exposed SiO2/SiN stacks. The aspect ratio of channel holes can exceed 50:1. A multi-step process is developed based on remote plasma chemistries containing hydrogen and fluorine radicals, in conjunction of a RF bias on wafer surface to improve directionality. SiOx-like residues of various thickness are initially completely removed at the bottom of high-aspect ratio structures. With a customized radical chemistry and a unique anisotropic process, there is no sidewall SiN/SiO2 damage and a minimal CD change. Followed by a selective removal of damaged silicon layer and surface contamination from prior etch process, a pristine and coherent surface can be prepared for the subsequent epitaxial deposition. Contact hole clean: The main objective is to remove amorphous silicon or silicon oxide interface layer at bottom of high aspect ratio contact hole structures in order to minimize metal contact resistance. The aspect ratio of contact hole structures can exceed 50:1 in advanced 3D NAND devices. Device process flow requires a high selectivity towards tungsten. A fluorine-containing remote plasma process was developed to effectively remove oxidized Si residues, create enough gouging depth, and maintain contact hole structure integrity at the same time. Contact resistance is significantly reduced with the radical based dry clean process.

Correlation between gas-phase OH density and intensity of luminol chemiluminescence in liquid interacting with atmospheric-pressure plasma

The relationship between the density of OH radicals in the gas phase and the intensity of luminol chemiluminescence was investigated using an atmospheric-pressure plasma system in contact with liquid. A thin luminol chemiluminescence was observed just below the plasma–liquid interface when the plasma was generated on the aqueous solution surface with luminol. The radial region with the chemiluminescence was approximately 2.6 times larger than that of the plasma with the optical emission, and was similar to the diameter of the region with OH radicals in the gas phase. The decay time constant of the intensity of the luminol chemiluminescence in the afterglow phase of the pulsed discharge was approximately 100 s, while the optical emission intensity at the second positive system of molecular nitrogen decayed immediately after the termination of the discharge current. On the other hand, the decay time constant of the OH radical density was approximately 100 s in the afterglow phase. These experimental results indicate that the luminol chemiluminescence is induced by the transport of OH radicals to the plasma–liquid interface. It is considered that the chemiluminescence originates from the reaction with O which is produced by .

Spectroscopic analysis of gold nanoparticle synthesis using plasma liquid interaction technique

Surfactant free AuNPs were prepared via Plasma-Liquid Interaction (PLI) technique, using -plasma, as a function of time, discharge current and gas flow rate. Atomic oxygen [O] and nitrogen [N] densities were determined to study their effect on the intensities of UV radiation and OH radical, which in turns controls the synthesis of AuNPs. UV radiation, OH radical and atomic densities of [O] and [N] were determined through optical emission spectroscopy from gas phase plasma. The increase in UV radiation intensities and OH radicals with time was observed and results were verified by observing increasing trend in the [O] and [N] atomic densities. We report the role of versatile discharge species generated in PLI, like [O] and [N] atomic densities, in the control synthesis of surfactant free AuNPs.

Process Development of Radical Based Dry Clean for Advanced 3D NAND Fabrication

As semiconductor device scaling marching toward sub-5 nm logic, 128+ layers 3D NAND, and 1x nm DRAM, wafer surface cleaning and residue removal in nanoscale, high aspect ratio (AR) structures become increasingly critical. Dry plasma clean technologies based on reactive radicals are developed as alternatives for traditional wet clean applications with significant advantages in process extendibility and environmental friendliness. Here we report a novel inductively coupled remote plasma design for radical based dry clean applications. A high gas dissociation efficiency and a high radical density were achieved with controllable radical component, energy, and reactivity. Two applications, including residue clean in high aspect ratio channel holes and contact holes (AR ~ 50:1), are tailored for 3D NAND manufacturing. Complete removal of oxide and polymeric residues, smooth and pristine Si surface, and considerably reduce contact resistance can be simultaneously achieved with the customized clean chemistries. Applications in mass production have been accomplished.

Controlling Nitrogen Dose Amount in Atmospheric-Pressure Plasma Jet Nitriding

A unique nitriding technique with the use of an atmospheric-pressure pulsed-arc plasma jet has been developed to offer a non-vacuum, easy-to-operate process of nitrogen doping to metal surfaces. This technique, however, suffered from a problem of excess nitrogen supply due to the high pressure results in undesirable formation of voids and iron nitrides in the treated metal surface. To overcome this problem, we have first established a method to control the nitrogen dose amount supplied to the steel surface in the relevant nitriding technique. When the hydrogen fraction in the operating gas of nitrogen/hydrogen gas mixture increased from 1% up to 5%, the nitrogen density of the treated steel surface drastically decreased. As a result, the formation of voids were suppressed successfully. The controllability of the nitrogen dose amount is likely attributable to the density of NH radicals existing in the plume of the pulsed-arc plasma jet.

Application and evaluation of nitriding treatment using active screen plasma

Plasma nitriding was performed on samples of JIS SKD61 die steel, and the microstructure near the surface was analyzed. The plasma nitriding was performed using active screen plasma (ASP). In the ASP nitriding process, a dependency on the bias current applied to the sample was found.Emission spectra showed the presence of atomic nitrogen ions (N+), molecular nitrogen ions (N2+), hydrogen radicals (H), nitrogen radicals (N), and radicals consisting of nitrogen and hydrogen (NiHi). The densities of nitrogen and hydrogen radicals observed by vacuum ultraviolet absorption spectroscopy were 1.5 × 1011 and 1.0 × 1011 cm−3, respectively. Once the device current reached 0.25 A or more, the surface became cloudy. The cause of this cloudiness was investigated by X-ray diffraction and cross-sectional bright-field scanning transmission electron microscopy and was found to be a deposition layer around 50 nm thick of a mixed crystal containing the ε phase Fe23N and γ' phase Fe4N and the formation of a structure with a period of around 300 nm at the surface. Although deposition of Fe23N and Fe4N also occurred at the surface in samples without cloudiness, the deposition layer was only around 10 nm thick, and no periodic structure was formed. A chromium oxide-rich layer was found directly under the Fe23N and Fe4N deposition layer by scanning transmission electron microscopy with electron energy-loss spectroscopy. This chromium oxide-rich layer likely occurred due to selective etching of iron oxide and chromium oxide. In ASP nitriding method, the sputtering action of charged particles of N2+ and N+ was experimentally shown to play an important role in nitriding and surface morphology. Furthermore, it was discovered that there was no compound layer several micrometers thick as would form in the conventional nitriding process.

Control of hydrogen peroxide production in plasma activated water by utilizing nitrification

In this study, ammonia (NH3) vapor was added to an atmospheric pressure argon plasma jet generated by a sinusoidal power supply (with an applied voltage of 4 kV and frequency of 35 kHz) and it was analyzed by electrical, optical, and chemical probe measurements. A total gas flow rate of 1200 sccm under 2% flow rate of either water or ammonia solution at concentrations up to 0.75% mixed with 98% argon feeding gas. The dissipated power of the plasma jet estimated by voltage-charge plots was found to decrease continuously with increase in ammonia concentrations at a fixed applied voltage. The optical emission spectra inside the quartz tube obtained for the NH3 mixed plasma indicated the presence of nitrogen emission lines which were absent in the water only mixed argon plasma. Colorimetric measurements of hydrogen peroxide (H2O2) and nitrite () in plasma activated water (PAW) were performed at different consumed energy varied by plasma exposure time. The H2O2 concentration decreased to 4 ppm from 14 ppm, while the concentration simultaneously increased to 6 ppm from 1 ppm as the ammonia concentrations increased to 0.75% from 0% throughout 2.07 × 103 joule energy consumption. We also analyzed the corresponding variation of pH values, in absence of ammonia, PAW leads to acidification but addition of small amount of ammonia in plasma is sufficient to make it alkaline. Additionally, we measured the hydroxyl (OH) radical density in gas and liquid phases by utilizing UV absorption spectroscopy and chemical probe method, respectively. OH radical density in both phases also decreased with the increase in the NH3 concentrations. Experimental results obtained from this experiment can be attributed to control H2O2 concentrations in the PAW via plasma-assisted nitrification.

Active species densities in R/x%N2 and R/x%(N2-5%H2) (R = Ar or He) microwave early afterglows

Afterglows of R/x%N2 and R/x%(N2-5%H2) (R = Ar or He) flowing microwave discharges are characterized by optical emission spectroscopy. Absolute densities of N-atoms, N2(A) and N2(X,v>13) metastable molecules and N2+ ions and evaluated densities of NH and H are determined after calibration of the N-atom density by NO titration. New results on NH radical and H-atom relative densities are obtained by considering that the excitation of the NH(A) radiative state in the afterglow is produced by N2(X,v>13) + NH collisions. The interest of these results concerns the enhancement of surface nitriding by combined effects of N and H atoms inclusion in afterglow conditions.

Quantitative spectrochemical analysis of solution plasma in aromatic molecules

AbstractA nonthermal plasma produced at atmospheric pressure in the gas resulted from the surrounding liquid is named solution plasma (SP). A quantitative and comparative spectrochemical analysis of the plasma gas and solution in benzene, pyridine, and aniline is performed. The number densities of dicarbon and cyano radicals and hydrogen molecule from the plasma gas are measured using a cheap, straightforward, and home‐made optical set‐up. By simply modifying the optical set‐up, the molar concentration of newly formed chemical compounds is in situ obtained in the solution. The thermodynamic properties of aromatic molecules determine the electrical breakdown and the species number densities in the plasma gas. The production rate and atomic composition of carbon material are correlated with the radicals from plasma gas.

Characterization of dielectric barrier discharges with water in correlation to productions of OH and H2O2 in gas and liquid phases

Using several types of dielectric barrier discharges, we studied the production mechanisms of H2O2 molecules in gas and liquid phases. Water vapor was supplied by a water bubbler in a gas-feed line or vaporization of water filling a lower electrode well. Densities of OH radicals were measured by optical emission and laser-induced fluorescence spectroscopic methods and correlated with the H2O2 production in gas phase. The energy yield of H2O2 obtained in the gas-phase synthesis with the supply of water vapor through the bubbler was on the 0.1 g kWh−1 order, while that in the synthesis with liquid electrode was larger than 1 g kWh−1. We investigated also the transport of OH and H2O2 species from gas phase to liquid phase, using additional supply of H2O2 through the outside bubbler and ethanol as an OH scavenger admixed either in the bubbling water or electrode water. From those results, we conclude that the production of H2O2 mainly proceeds in gas phase and the difference in the yields is attributed to the efficiency of extracting the product out of the discharge region before being decomposed by the repetitive discharge, which depends on the reactor schemes.

Melatonin and the Optics of the Human Body

Melatonin is fundamental to the lighting, display, and architectural industries as the primary biomarker used in circadian theory. Billions of dollars are being spent on research, product development, and marketing based on the impact of visible light on melatonin produced by the pineal gland. It has now been shown that the mitochondria produce melatonin in many cells in quantities which are orders of magnitude higher than that produced in the pineal gland. This subcellular melatonin does not necessarily fluctuate with our circadian clock or release into the circulation system, but instead has been proposed to be consumed locally in response to the free radical density within each cell, in particular in response to Near Infrared (NIR) exposure. The main point of this review hypothesizes that the subcellular melatonin is being produced in response to the NIR photons which make up the majority of natural sunlight. Given the number of cells and quantity of subcellular melatonin identified to date, it is reasonable to propose that the body produces and maintains a melatonin reservoir that is separate and apart from the circulatory melatonin generated by the pineal gland. To understand how sunlight may support or stimulate this antioxidant reservoir, it becomes necessary to quantify the free radical density in various parts of the human body. To do this, it is necessary to move away from two-dimensional empirical approaches and develop three-dimensional bio-optical models based on the underlying biological processes at play. Three-dimensional Mechanistic Bio-optical Models (MBM) of the skin, eye, and brain based on non-sequential optical ray tracing and Electron Spin Resonance (ESR) data clearly indicate that the NIR portion of natural sunlight provides the primary stimulus during the day to the majority of the cells in the human body, impacting over 60% of the cells in an adult body and 100% of the cells in the fetus and young children. It is also shown that optically, the human body, under the assumption of natural sunlight, has developed optical mechanisms to gather and localize NIR photons in the most sensitive areas of the human body: blood vessels, retina, brain, skin, and even the fetus. That assumption is no longer valid in modern societies where the majority of our time is spent exposed to visible only lighting and displays, which emit zero NIR photons. Based on an optical and biological review of the literature and the MBM results, it is proposed that the NIR portion of natural sunlight stimulates an excess of antioxidants in each of our healthy cells and that the cumulative effect of this antioxidant reservoir is to enhance the body’s ability to rapidly and locally deal with changing conditions throughout the day. In this approach the role of circulatory melatonin produced by the pineal gland is to provide an efficient method of delivering supplemental melatonin during periods of low cellular activity and solar stimulus to damaged or aging cells in both diurnal and nocturnal animals. While circulatory melatonin may be the “Hormone of Darkness”, subcellular melatonin may be the “Hormone of Daylight”.

Control of sp2-C cluster incorporation of amorphous carbon films grown by H-radical-injection CH4/H2 plasma-enhanced chemical vapor deposition

Amorphous carbon (a-C) thin films were deposited under the control of C2 radical density using radical-injection plasma-enhanced chemical vapor deposition (RI-PECVD) with CH4/H2 plasma. By actinometric monitoring of C2 emission intensities, the plasma parameters were precisely controlled by changing in CH4-containing plasma excitation power independent of H2 plasma excitation. The control of the incorporation of sp2-C clusters in the a-C films during the a-C film depositions is demonstrated by tailoring Raman positions vs. full widths at half maxima for the G band around 1580 cm–1 to the RI-PECVD parameters.

Analysis of the charge transfer and separation in electrically doped organic semiconductors by electron spin resonance spectroscopy

Abstract We investigated the charge generation mechanism of electrically doped organic semiconductors (OSs) by electron spin resonance (ESR) analysis. ESR spectroscopy was used to successfully evaluate the radical density of p-doped OSs to estimate the charge transfer efficiency (CTE) of various doped systems. The results showed that the CTE is efficient close to 100% if the dopant molecules are homogenously dispersed and the energy difference (ΔE) between the highest occupied molecular orbital (HOMO) level of the host molecule and lowest unoccupied molecular orbital (LUMO) level of the p-dopant is large. The charge separation efficiency to form free carriers from the radicals is rather low (less than 12% in this study) and is a dominant factor controlling the charge generation efficiency (CGE). An organic dopant molybdenum tris[1,2-bis(trifluoromethyl)ethane-1,2-dithiolene] turns out to be an efficient dopant with the CGE of 9.7% due to high CTE originating from homogenous dispersion of the organic p-dopants and low LUMO level, i.e., large ΔE.

Modeling of a Dielectric-Barrier Discharge-Based Cold Plasma Combustion Ignition System

We present a computational modeling study of plasma phenomena in a dielectric-barrier discharge (DBD) for automotive combustion ignition applications. The study was performed using a self-consistent, two-temperature plasma model with finite-rate plasma chemical kinetics for methane-air combustion mixture. The structure of a DBD discharge and the yield of active combustion enhancing radicals from the discharge is quantified for positive and negative pulsing, and a comparison is made with a single electrode corona discharge. The DBD plasma develops as a streamer discharge with individual streamers preferentially emerging from sharp features on the bare electrode of DBD which quickly propagates to the opposite dielectric surface where it is quenched. The dielectric barrier therefore self-limits the discharge resulting in a total radical yield that saturates in time. The corona on the other hand provides a radical yield that can continuously increase in time. The negative polarity pulsing of the DBD results in a more intense plasma with a higher radical yield compared to a positive polarity pulse. Simulations are also performed for a long 1-μs duration afterglow period once the active pulse is terminated. The active combustion enhancing radicals are found to remain relatively stable in density over this duration, indicating that ~100-kHz pulse repetition rates can sustain or even gradually increase the radical densities over long durations of transient time.

Fully coupled modeling of nanosecond pulsed plasma assisted combustion ignition

A coupled 2D computational model of nanosecond pulsed plasma induced flame ignition and combustion for a lean H2–air mixture (dry air) in a high pressure environment is discussed. The model provides a full fidelity description of plasma formation, combustion ignition, and flame development. We study the effects of three important plasma properties that influence combustion ignition and flame propagation, namely (a) plasma gas temperature, (b) plasma produced primary combustion radicals O, OH and H densities, and (c) plasma generated charged and electronically excited radical densities. Preliminary 0D studies indicate that plasma generated trace quantities of O, OH and H radicals drastically reduce the ignition delay of the H2–air mixture and become especially important for high pressure lean conditions. Multi-dimensional simulations are performed for a lean H2–air mixture () at 3.3 atm and an initial temperature of 1000 K. The plasma is accompanied by fast gas heating due to N2 metastable quenching that results in uniform volumetric heating in the interelectrode gap. The spatial extent of the high temperature region generated by the plasma is a key parameter in influencing ignition; a larger high temperature region being more effective at initiating combustion ignition. Plasma generation of even trace quantities (~0.1%) of primary combustion radicals, along with plasma gas heating, results in a further fifteen-fold reduction in the ignition delay. The radical densities alone did not ignite the H2–air mixture. The generation of other plasma specific species results only in a slight ~10% improvement in the ignition delay characteristics over the effect of primary combustion radicals, with the slow decaying ions () and oxygen metastable species () primarily contributing to combustion enhancement. These species influence the ignition delay, directly by power deposition due to quenching, attachment and recombination reactions, and indirectly by enhancing production of primary combustion radicals.

Electrochemical Properties of Nanocomposite Based on Polytriphenylamine Derivative and Single-Walled Carbon Nanotubes

One-step synthesis of the stable dispersion of conjugated poly(4,4',4"-tris(N,N-diphenylamine) triphenylamine)—single-walled carbon nanotubes nanocomposite is carried out by the oxidative polymerization of the monomer of the triphenylamine derivative with a high density of free radicals of 4,4',4"- tris(N,N-diphenylamine)tripenylamine in the presence of the single-walled carbon nanotubes in concentrated formic acid. Benzoyl peroxide is used as an oxidant. Electroconductive film coatings are prepared by applying stable dispersion onto the Ni substrate. The coatings show a high specific electrochemical capacity and stability in long-term cycling in the aprotic 1 M LiClO4/propylene carbonate electrolyte.