Optical Emission Spectroscopy Technique Research Articles

Application of argon collisional-radiative model for inductive RF discharge research

The technique of optical emission spectroscopy (OES) in combination with plasma emission models for determining the parameters of a gas discharge is presented. Measurements of charge carrier concentration and electron temperature in an inductively coupled RF plasma of argon are carried out under low pressure. The concentration and temperature of electrons were determined by selecting the ratio of the intensities of the spectral lines calculated with the collision-radiative model (CRM) to the intensities of the lines obtained in the experiment. The model describes the kinetics of the first 30 excited states of argon and takes into account the following processes: direct electron impact excitation / relaxation, spontaneous emission, radiation trapping, electron impact ionization and charge loss due to diffusion on the walls. The obtained OES results were compared with the results of Langmuir probe measurements of plasma parameters.

Structural and photoluminescence properties of Y2O3 and Y2O3:Ln3+ (Ln = Eu, Er, Ho) films synthesized by plasma electrolytic oxidation of yttrium substrate

Plasma electrolytic oxidation (PEO) of yttrium is performed for the first time and is shown that Y2O3 and trivalent rare-earth ions (Eu3+, Er3+ or Ho3+) doped Y2O3 films can be formed by PEO in alkaline electrolyte without or with addition of rare-earth oxide particles (Eu2O3, Er2O3 or Ho2O3), respectively. The elements present in PEO micro-discharges were identified using optical emission spectroscopy technique. The gas plasma temperature of (3000 ± 300) K was estimated from the intensity distribution within a part of an OH spectrum. The morphology, chemical composition, crystal structure, formation process and photoluminescence (PL) properties of formed films were investigated. Diffraction patterns of formed films show well pronounced reflections inherent to pure cubic phase of Y2O3. PL characterization of Y2O3 and Y2O3:Ln3+ (Ln = Eu, Er, Ho) films is performed through excitation and emission spectra. An intense red PL emission was observed from the Y2O3:Eu3+ and a green emission was observed from Y2O3:Er3+ and Y2O3:Ho3+ films.

Quantification of atomic hydrogen anion density in a permanent magnet based helicon ion source (HELEN) by using pulsed ring down spectroscopy.

In the present work, a permanent magnet-based helicon plasma source (HELEN) is characterized as a negative ion source. A noninvasive diagnostic technique based on cavity ring down spectroscopy (CRDS) is developed to measure the line-integrated negative hydrogen ion (H-) density in HELEN. This paper discusses the experimental results in which negative hydrogen ion density is measured for different magnetic field, pressure, and RF (13.56 MHz) power configurations. It is observed that in high power range (800-850 W), the source is operating in helicon wave heating mode with a background plasma density of ∼1018 m-3 and electron temperature of ∼2 eV. Negative hydrogen ion density is measured by CRDS method and also by optical emission spectroscopic technique. The measured negative ion density is in the range of ∼1016 m-3 under volume mode operational condition even without any use of standard magnetic filter or cesium seeding in the downstream region. The influence of pressure variation (pressure range from 4 × 10-3 mbar to 4 × 10-2 mbar) on negative ion density production is not significant, except for a particular axial magnetic field configuration (55 G) and at 8 × 10-3 mbar pressure, where ∼34% hike is observed.

Enhancement of O-atom density through collisions with Ne by laser-produced plasma in Ne–O2 gas mixtures and possible energy transfer mechanism

Laser-produced plasma in Ne and O2 gases and Ne–O2 gas mixture with different O2 fractions have been investigated. The plasma were produced by focusing a laser beam of 5 ns pulse duration from a Nd:YAG laser ([Formula: see text] = 1064 nm) through a lens of 5 cm focal length into the chamber filled with different gas species at different pressures. Possible enhancement in O-atom densities through collisions with metastable Ne atoms by the laser-created plasma in Ne–O2 gas mixtures and possible energy transfer mechanism was studied. Study of energy transfer through collisions was carried out by comparisons of the line intensities of the emitted spectra from laser-created plasma in gas mixtures and pure gases with the technique of optical emission spectroscopy (OES). Strong evidence of energy transfer from Ne to O was recorded. From the result, it was suggested that the high-lying metastable levels of Ne were responsible for enhancement of O-atoms density in gas mixture and Ne also play important role in energy transfer mechanism through collision. Also, behaviors of the line intensities under different laser energies were studied. Behaviors of line intensities and line widths were the main parameters measured. Stark broadening of lines in Ne with different laser energies was recorded. The electron temperature T[Formula: see text] and number density N[Formula: see text] were found to be 1.01 eV and 9.44 × 10[Formula: see text] cm[Formula: see text] in Ne at different laser energy/pulse with total pressure of 1000 mbar.

Laser induced breakdown optical emission spectroscopic study of silicon plasma.

The laser induced breakdown optical emission spectroscopy technique has been employed for the analysis of silicon sample in the atmospheric air. Laser irradiance of 1 × 1011 Wcm-2 was created on specimen of silicon sample surface to generate the plasma plume by using the fundamental of Nd:YAG laser pulse. This laser produced silicon plasma was captured through the LIBS 2000 Spectrometer for the subsequent analysis of silicon sample. The electron temperature of silicon plasma is estimated to be 7500 K to 4000 K while electron number density of silicon plasma lies 3.2 × 1017 to 1.8 × 1017. In spatially resolved laser induced plasma and this temperature of silicon plasma has been estimated from the Boltzmann plot method to be in local thermodynamic equilibrium, and electron number density of silicon plasma has been estimated from the Stark width broadening at λ ~ 288.1 nm respectively. Observed result in spatially resolved laser plasma which shows the recombination rate of plasma plume along the direction of expansion. Which also affects on the temperature and density of silicon plasma besides the intensity decreasing factor with distance in silicon ionic and neutrals transition lines is discussed.

Controlled Delivery of Brain Derived Neurotrophic Factor and Gold-Nanoparticles from Chitosan/TPP Nanoparticles for Tissue Engineering Applications

Brain derived neurotrophic factor (BDNF) is highly effective in the treatment of various diseases, and selected for growth factor delivery system. Also, gold-nanoparticles (AuNPs) plays the paramount role in diagnosis and treatment of diseases. The aim of this study is to encapsulate BDNF and AuNPs in chitosan nanoparticles and its effect on human adipose derived stem cells (h-ADSCs) proliferation was evaluated. The ratio of 1:3 chitosan/TPP was determined as the optimum ratio, BDNF or AuNPs were added to 0.1% chitosan solution for preparation of nanoparticles. The release rate of BDNF and AuNPs were assessed by Bradford test and inductive coupled plasma optical emission spectrometry technique, respectively. In this study, BDNF and AuNPs loading efficiency were 89.46 ± 2.77 (%) and 93.8 ± 2.12 (%), respectively. The kinetic release of BDNF is 83.28 ± 2.22 (%) and AuNPs release rate was 48.4 ± 0.108(%), during the 7 days. MTT findings demonstrated h-ADSCs viability in the presence encapsulated BDNF and AuNPs is significantly more than control group on 3 and 7 days (p < 0.05). These findings indicate the controlled release of encapsulated BDNF and AuNPs, and synergist effects of nanoparticles on h-ADSCs viability; it suggests an efficient delivery of BDNF and AuNPs, for tissue engineering.

Experimental Parameterization of a Pseudo Two-Dimensional (P2D) Model for Lithium Ion Batteries: A Study of a Commercial Cell

Modelling of lithium ion batteries is important, as it provides a way to predict their performance under various operating conditions, as well as the state of health during cycling, thereby providing key guidance in the designing of these devices. Among the numerous models studied in literature, the pseudo two-dimensional (P2D) model developed by the Newman group, is one of the most widely adopted lithium-ion battery model.1 To build a precise P2D battery model with predictive value, one crucial part is parameterization. However, accurate measurement of such complex physical and chemical processes is challenging and existing literature data is incomplete at best.2 In this contribution, we adapt and demonstrate an experimental procedure to determine a complete set of parametric inputs required for a P2D model with reduced order. Designing the experiments with the model explicitly in mind, allows us to identify the crucial inputs, to able the model to capture the existing system accurately as well to use it as a predictive tool for the design of new systems. Experimental results presented herein are based on a commercially available cylindrical cell from LG Chem. (M50), of which the design and material content is unknown. The electrodes were extracted from this commercial cell to enable material characterization. The physical and chemical parameters of the electrodes and cells were investigated; the chemical and structural properties analysed with X-ray diffraction, electron microscopy and inductively coupled plasma – optical emission spectroscopy (ICO-OES) techniques. The electrochemical properties such as the electronic and ionic conductivities were analysed in small test coin and Swagelok™ cells with extracted electrodes under different charging and relaxation conditions.

The mixture of silver nanosquare and silver nanohexagon: green synthesis, characterization and kinetic evolution

The kinetic studies of preparation silver nanosquare (AgNS) and silver nanohexagon (AgNH) were made by rapid and green synthesis route using ziziphus spina-christi leaf powder with silver nitrate solution. The growth kinetics of silver nanoparticles as a function of time or pH were investigated. The optimal pH was studied by measuring the absorption maxima at different pH intervals (2–8) after treating the reducing agent with the silver nitrate solution. Moreover, the zeta potential was measured at different pHs for detecting the surface charge of Ag nanoparticles in its colloidal solution. The overall available silver ions after 2–25 min and the optimum Ag ion concentration were measured using inductively coupled plasma- optical emission spectroscopy (ICP-OES) technique. Furthermore, the time-dependent growth of crystalline was studied by measuring the increase in size along with the full width at half maximum (FWHM) that was taken from x-ray diffraction. The changes in the oxidation and reduction potentials of the Ag nanoparticles with time were studied to determine the optimum time. The prepared silver nanostructures at optimum conditions were characterized using electronic spectrum (UV–vis), infrared spectrum (IR), x-ray diffraction studies (XRD), zeta sizer, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDX).

Elemental Characterization of Neutron-Irradiated Tungsten Using the GD-OES Technique

In reactor-relevant fusion divertor conditions, tungsten (W) will be used as an armor material due to its excellent thermal properties. It will be exposed to impurities from numerous sources, including ion implantation and mixing, neutron transmutation, low-Z plasma-facing-component (PFC) redeposition and codeposition of deuterium and tritium fuel, and trapped helium bubbles. The impurity plasma material–interaction effects are a concern because they can cause gradual degradation of the material and of plasma performance due to dust formation, fuel retention, and even changes to the thermal and mechanical properties of the W armor. It is crucial to measure the amount of impurities in W, and the glow discharge–optical emission spectroscopy (GD-OES) technique is exceptionally well suited for analysis of irradiated samples. GD-OES can measure a sample’s elemental composition by sputtering the surface of the sample, ionizing the eroded material, and measuring the optical emission of the excited atoms. In order for the GD-OES technique to be applied to neutron-irradiated tungsten samples, a mounting system for miniature samples was designed. The sample mounting and centering procedure was successful in measuring the depth distribution of control W and W alloy sample elemental concentrations. These control depth spectra will be used as elemental references for postirradiated samples. The residence time of surface layers was measured, a comparison of signals from different anodes was completed, and the influence of initial surface roughness or nonuniformity was understood. The depth distribution of an arc-welded W-0.4% rhenium (Re) alloy was measured to have a stable Re signal that was distributed evenly in the W matrix. The methods developed here will allow for quantification of impurities and transmutation amounts in neutron-irradiated W. GD-OES is a powerful tool but requires calibration and careful optimization of the parameters to obtain meaningful results.

Charge transfer mechanisms underlying Contact Glow Discharge Electrolysis

Understanding charge transfer at strongly polarised gas-evolving electrodes is crucial for the development and control of Contact Glow Discharge Electrolysis (CGDE), a method of interest in a wide range of applications spanning from biochemistry to materials engineering. Since the pioneering work of Kellogg in 1950, the transition from conventional electrolysis to the CGDE regime has been generally associated with excessive ohmic heating at the working electrode, disregarding basic principles of electrochemical kinetics. Here we attempt to address this controversy by investigating of a CGDE process at a Fe-13%Cr anode in aqueous solutions of (NH4)2SO4 using an original method of in-situ impedance spectroscopy combined with voltammetric, gravimetric, chemical analysis and optical emission spectroscopy techniques. The study reveals three characteristic relaxation processes representing charge transfer through the surface oxide-hydroxide layer, the presence of which is confirmed by Glow Discharge Optical Emission and Raman Spectroscopies, and adsorption-desorption behaviour which we identify with oxo- and peroxo-intermediates of the oxygen evolution reaction (OER) coupled with anodic metal dissolution. We explain the transition to CGDE by the OER pathway change from direct recombination of two terminally coordinated oxides to a single-site route involving early peroxide formation. This change triggers electrochemical luminescence which proceeds via a co-reactant mechanism involving fragments of metastable peroxide structures and metal cations at the active sites on the anode surface that produce electrically excited intermediates prone to radiative relaxation. Our results undermine existing CGDE theories whilst emphasising common bases in behaviour of conventional and plasma-assisted electrochemical systems, thus providing far-reaching implications for understanding, development and practical use of electrolytic plasma processes.

Graphene synthesis by microwave plasma chemical vapor deposition: analysis of the emission spectra and modeling

In this article, we report on some of the fundamental chemical and physical processes responsible for the deposition of graphene by microwave plasma-enhanced chemical vapor deposition. The graphene is grown by plasma decomposition of a methane and hydrogen mixture (CH4/H2) at moderate pressures over polycrystalline metal catalysts. Different conditions obtained by varying the plasma power (300–400 W), total pressure (10–25 mbar), substrate temperature (700 °C–1000 °C), methane flow rate (1–10 sccm) and catalyst nature (Co–Cu) were experimentally analyzed using the in situ optical emission spectroscopy technique to assess the species rotational temperature of the plasma and the H-atom relative concentration. Then, two modeling approaches were developed to analyze the plasma environment during graphene growth. As a first approximation, the plasma is described by spatially averaged bulk properties, and the species compositions are determined using kinetic rates in the transient zero-dimensional (0D) configuration. The advantage of this approach lies in its small computational demands, which enable rapid evaluation of the effects of reactor conditions and permit the identification of dominant reactions and key species during graphene growth. This approach is useful for identifying the relevant set of species and reactions to consider in a higher-dimensional model. The reduced chemical scheme was then used within the self-consistent two-dimensional model (2D) to determine auto-coherently the electromagnetic field, gas and electron temperatures, heavy species, and electron and ion density distributions in the reactor. The 0D and 2D models are validated by comparison with experimental data obtained from atomic and molecular emission spectra.

Functionalization of 3D Polylactic Acid Sponge Using Atmospheric Pressure Cold Plasma

The deposition of organic functionalities on biomaterials to immobilize biomolecules is a research area of great interest in the medical field. The surface functionalization of a 3D porous scaffolds of PDLLA with carboxyl (-COOH) and amino (-NH2) groups by cold plasma treatment at atmospheric pressure is described in this paper. Two methods of continuous and pulsed plasma deposition were compared to assess the degree of functionalization of the internal porous 3D scaffold. In particular, the pulsed plasma treatment was found to functionalize uniformly not only the sample surface but also inside the open cavities thanks to its permeability and diffusion in the porous 3D scaffold. The species developed in the plasma were studied by optical emission spectroscopy (OES) technique, while the functionalization of the sponges was evaluated by the Diffuse Reflectance Fourier-Transform Infrared Spectroscopy (DR-FTIR) technique using also the adsorption of ammonia (NH3) and deuterated water (D2O) probe molecules. The functional groups were deposited only on the front of the sponge, then the structural characterization of both front and back of the sponge has demonstrated the uniform functionalization of the entire scaffold.

Experimental investigation of dusty plasma characteristics in AC discharge system

In the present work, the effect of size of zinc dust particles onAC argon discharge characteristics are investigatedexperimentally. The plasma characteristics are determined byusing optical emission spectroscopy (OES) techniques. Theresults illustrated that the electron temperature (Te) in the presentand absent of Zinc dust particle is reduced with increasing ofpressure. The electron temperature decreases with increasing ofZinc dust size. Excitation temperature Tex is reduces withincreasing of Ar pressure in present and absent of zinc dustparticles. The present of Zinc dust reduce the Tex of Ar in bothZinc dust size. The electron density increasing in the present andabsent of both zinc dust size. Furthermore, the introduced of zincdust in AC discharge increasing of ne.

Impact of flotation hydrodynamics on the optimization of fine-grained carbonaceous sedimentary apatite ore beneficiation

The flotation beneficiation of phosphate ore is increasingly facing challenges, especially for finely disseminated sedimentary ores rich in carbonates. This study aims to optimize and assess the impact of key hydrodynamic parameters including pulp density, air flowrate and impeller speed on flotation and metallurgical responses (i.e. grade, recovery, flotation rate constant and selectivity index (SI)). We carried out locked cycle flotation tests using the best conditions from the rougher flotation test to generate an experimental simulation of a continuous circuit. The mineralogical and chemical properties were characterized by mineral liberation analysis (MLA) and inductively coupled plasma optical emission spectroscopy (ICP-OES) techniques, respectively. A modified-McGill bubble size viewer was used for measuring bubble sizes and evaluating the interaction between hydrodynamic factors and bubble diameters. Finally, the design of experiment (DOE) method was applied to determine the relative intensity of the studied factors. It was found that under optimal conditions with the targets of high recovery and maximum SI, the final apatite concentrate achieved a recovery of 86.3% at a grade of 35.5%, while the MgO content was 1.2% and 84.3% of dolomite was removed from a feed ore containing about 25% P2O5, 4.6% MgO, and 41% CaO. Furthermore, another locked cycle flotation test showed that a 0.82% MgO content in the final apatite concentrate can be achieved with an apatite recovery of 75.6% at a P2O5 grade of 36.76%, and a ratio CaO/P2O5 = 1.33. The obtained concentrate in this investigation under the optimum conditions is the highest in both apatite recovery and grade with low MgO content reported in the literature.

Spectroscopic study of micro-discharges during plasma electrolytic oxidation of Al-Zn-Si alloy

Plasma electrolytic oxidation (PEO) process of Al?Zn?Si alloy in water solution containing 4 g L-1 sodium metasilicate at constant current density of 400 mA cm?2 was investigated. The species present in PEO micro-discharges and their ionization stages were identified using optical emission spectroscopy technique. The obtained PEO spectrum consists of atomic/ionic lines originating from the elements present both in the substrate (Al, Zn) and the electrolyte (Na, O, H). Apart from atomic and ionic lines, AlO band at 484.2 nm was also detected. Plasma electron number density diagnostics was performed from the H? line shape. The electron temperature of 4000?400 K was estimated by measuring the relative line intensities of zinc atomic lines at 481.05 and 636.23 nm. In addition, surface morphology, chemical and phase composition of oxide coatings were investigated by SEM-EDS and XRD. Oxide coating morphology is strongly dependent of PEO time. The elemental components of PEO coatings are Al, Zn, O and Si. The oxide coatings are partly crystallized and mainly composed of gamma phase of Al2O3.

Electrodeposition of nickel from alkaline NH4OH/NH4Cl buffer solutions

Abstract The electrodeposition of nickel on steel and copper from alkaline NH4OH/NH4Cl buffer solutions was investigated by cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA) as well as an opto-digital microscope, glow-discharge optical emission spectroscopy (GD-OES), XRF, and SEM-EDS techniques. The aim was to obtain Ni coatings from weak alkaline solutions and to optimize the process. The electrolyte composition, pH, temperature as well as current and potential parameters of the process were optimized using the quality of Ni deposit as a criterion. The role of hydrogen evolution in the process was discussed. An influence of Co as an additive was also investigated. It was found that a small amount of Co catalyzes Ni deposition process and improves the quality and color of the deposit. Therefore, in the possible application, the Ni/Co codeposition should be seriously considered. It was also shown that for constant current deposition mode, the width of self-established potential range, revealed at the very beginning of the process by the chronopotentiometric E=f(t) curves, is related to the quality of the coating.

Experimental Study of Ethanol and Helium Mixture Glow Discharge

This paper focuses on the study of a glow discharge generated from a mixture of ethanol (C 2 H 6 O) and helium (He). Plasma was generated at different concentrations of C 2 H 6 O and He gases maintained at a total pressure of 2 torr. We used optical emission spectroscopy (OES) to analyze the discharge mixture at different concentrations of He. The species identified by the OES technique correspond to O 2 , CO + , CO, H β , H α , and He. A single Langmuir probe was used to obtain the electron temperature (Te) and electron density (ne). Te was found to be below 1.2 eV and ne in the order of 1010 particles per cm 3 .

Inactivation of Candida albicans biofilms by atmospheric gliding arc plasma jet: effect of gas chemistry/flow and plasma pulsing

Candida spp are present in 70%–90% of invasive infections and non-thermal plasmas operated at atmospheric pressure have been gaining attention as a new antimicrobial strategy for medical devices. This work presents studies on the inactivation efficacy of biofilms of Candida albicans grown in polyurethane (PU), main constituent of central venous catheter, by atmospheric gliding arc plasma jet operated at different process parameters: gas chemistry/flow (argon, helium, or its mixture with air) and plasma pulsing. The investigation was performed in the post-discharge region of the plasma jet. After plasma treatment, the colony-forming units (CFU) were counted, and the chemical bonding (FT-IR) and morphological (SEM) analyses of the surface of the biofilm plus PU substrate were investigated. Furthermore, optical emission spectroscopy (OES) technique was applied to characterize the plasma chemistry and measure the OH concentration and rotational temperature, together with thermal analyses of the substrate during treatment. CFU results showed that gliding arc plasma jet was efficient for the inactivation of C. albicans biofilms. It obtained a maximum CFU reduction of 100% and 98% for 4 L min−1 air/6 L min−1 He and 99% and 98% for 4 L min−1 air/6 L min−1 Ar in continuous and pulsed mode, respectively. SEM and FT-IR analyses corroborate with results of % CFU reduction, showing a reduction of the biofilm constituents on the substrate surface. From OES and substrate thermal analyses, it was possible to verify that, although the OH concentration and rotational temperature of air/He plasma jet are lower in comparison to the air/Ar, a drastic increase of the substrate temperature during the treatment (up to 70 °C) was observed for this plasma chemistry.

Technical characteristics of a DC plasma jet with Ar/N2 and O2/N2 gaseous mixtures

In this paper, the optical emission spectroscopy technique is used to examine the physical properties and technical characteristics of the plasma discharge in a fabricated DC plasma jet. The background gas is nitrogen molecular gas which is mixed with argon and oxygen gases at various percentages. The emission spectra are analyzed and, the plasma density, rotational, vibrational and excitation temperatures are obtained for the formed plasma discharges with Ar/N2 and O2/N2 mixtures. Moreover, the NO and OH lines from NOγ(A2Σ+→X2Πr), (A2Σ,v=0→X2Π,v′=0) excitation transitions are observed. It is shown that, at the higher argon and oxygen percentages in both the Ar/N2 and O2/N2 gaseous mixture, the emission intensities of argon ions and oxygen atoms are increased. In addition, at the higher Ar and O2 contributions in both the gaseous mixtures, while the rotational, vibrational and excitation temperatures are higher, they are decreased at the O2/N2 gaseous mixture. Moreover, the plasma electron density reduces for O2/N2 and increases for Ar/N2 gaseous mixture. On the other hand, for both the mixtures, the plasma density, rotational, vibrational and excitation temperatures are increased at the higher DC power source currents. Furthermore, it is seen that the N2 dissociation rate increases at the higher DC currents and Ar and O2 percentages in both the mixtures. However, N2 dissociation rate in the formed plasma jet with Ar/N2 gaseous mixture is higher.

Spectroscopic study the plasma parameters for Pb doped CuO prepared by pulse Nd:YAG laser deposition

In this work, plasma parameters such as, the electron temperature )Te(, electron density ne, plasma frequency )fp(, Debye length )λD(and Debye number )ND), have been studied using optical emission spectroscopy technique. The spectrum of plasma with different values of energy, Pb doped CuO at different percentage (X=0.6, 0.7, 0.8) were recorded. The spectroscopic study for these mixing under vacuum with pressure down to P=2.5×10-2 mbar. The results of electron temperature for X=0.6 range (1.072-1.166) eV, for X=0.7 the Te range (1.024-0.855) eV and X=0.8 the Te is (1.033-0.921) eV. Optical properties of CuO:Pb thin films were determined through the optical transmission method using ultraviolet visible spectrophotometer within the range (190 – 1100) nm.