Optical Emission Spectroscopy Technique Research Articles

Honey from Stingless Bee as Indicator of Contamination with Metals

Melipona scutellaris (Apidae, Meliponini) is one of the main species of stingless bees used in beekeeping in the Northeast of Brazil. We examined the honey from M. scutellaris as an indicator to evaluate the levels of metals at sampling sites subject to a broad spectrum of environmental pollutants. The collections were carried out in the urban-industrial area of Salvador, Bahia and the metropolitan region. Samples (n= 58) were submitted to the nitroperchloric digestion procedure. We used the inductively coupled plasma optical emission spectrometry technique (ICP OES) to determine the concentration of metals (Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) in the samples. The studied metals were detected among the samples, which presented tolerable levels according to current Brazilian legislation and recommendations from the World Health Organization (WHO), except for Cr, which presented mean values higher than the threshold for all sampling sites. The detection of the analyzed metals indicates that the honey of M. scutellaris is a useful tool to evaluate the presence of environmental contaminants; therefore, it can be considered a good indicator of environmental contamination for monitoring a particular region and preventing issues due to the release of metals into the environment.

Multifunctional finishing of cotton fabric by electron beam radiation synthesized silver nanoparticles

A radiation induced in-situ synthesis of silver particles in cotton fabrics, padded with different initial concentration of an aqueous alcoholic silver nitrate solution, has been accomplished by exposing them to different doses of electron beam (EB) radiation in an inert environment. The amount of synthesized silver particles has been studied as the function of initial solution concentration and EB radiation doses. The treated fabrics were characterized for the surface morphology with the aid of Scanning Electron Microscopy (SEM). The homogeneous and uniform coating of silver particles having an average size of 81 nm was observed on the fibre surface. The quantitative deposition of silver nanoparticles was estimated by inductively coupled plasma‒optical emission (ICP‒OES) spectroscopy technique. Their quantity was found to vary with concentration of the solution used for padding and EB doses, specifically more on the former. In this connection, deposited nanoparticles produced visual colour change in cotton fabrics with light to deeper shade which could be controlled primarily by concentration of solution used for padding. A reflectance and transmittance spectrum in the UV‒Vis region confirmed UV radiation blocking property of the fabric that also dependents on the solution concentration used for padding. Fabric samples exhibited antibacterial behaviour against two different microorganisms, S. Aureus and K. Pneuomonia. Ultraviolet protection (UPF) and antibacterial properties remained similar even after ten washing cycles, carried out as per standard washing procedure. This functional finishing did not adversely affect the air permeability and bending length properties of the fabric to a significant level but introduced a positive change of increased total crease recovery angle.

Influence of laser-produced plasma parameters on the deposition process: in situ space- and time-resolved optical emission spectroscopy and fractal modeling approach

The formation and dynamics of Al and Ag–Ni–Fe plasmas were studied through ICCD imaging and space- and time-resolved optical emission spectroscopy techniques. The experiments were conducted in pulsed laser deposition configuration and the surface topography and chemical composition of the obtained thin films were analyzed. For both targets, a splitting of the plasma plume was observed. Two structures with distinct velocities were analyzed and associated with different types of species: the ions were found predominantly in the fast structure while the excited species were observed mainly in the slow structure. Their different velocities were correlated to the different ejection mechanisms which lead to plasma formation. The angular distributions of the plasma front velocity were analyzed and associated with the mass of the main elements found in the plume. The excitation temperature determined for excited species presented a more uniform distribution than the one calculated for ions using the Boltzmann plot. The experimental results were described by a non-differential theoretical model which took into account the scattering probability, collision frequency and the fractality of the plasmas.

Analytical and experimental analyses for mechanical and biological characteristics of novel nanoclay bio-nanocomposite scaffolds fabricated via space holder technique

Abstract In the present work, bioactive nanoclay-TiO2 (NC-T) bio-nanocomposite scaffolds containing different TiO2 weight fractions are fabricated spacer for bone tissue engineering applications via the space holder technique using NaCl particles as the. The microstructure, surface morphology (porosity) and bioactivity potential of the manufactured bio-nanocomposite scaffolds are examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), energy dispersive spectroscopy (EDS), and inductively-coupled plasma optical emission spectroscopy (ICP-OES) techniques. The scaffold with optimized mechanical properties is predicted as NC-15wt%T with proper interconnected porosity and micro/macro pore size within the range of 1–2 (μm) and 3–5 (μm), respectively. Also, its mechanical properties including compressive strength, elastic modulus and crystallite size are extracted equal to 5.74 MPa, 438 MPa and 70–120 nm, respectively. The feasibility of the fabricated scaffolds for bioactive bone tissue engineering application (apatite deposition) is also evaluated using simulated body fluid (SBF) and physiological saline (PS) solutions. At the end, the nonlinear bending and vibration characteristics of an axially loaded beam-type bone implant made of the NC-T/NaCl bio-nanocomposite scaffolds are predicted analytically. In general view, the obtained results indicate that the NC-15wt%T/NaCl bio-nanocomposite scaffold may have excellent advantages for future research in bone regenerative applications.

Limit of detection and hardness evaluation of some steel alloys utilizing optical emission spectroscopic techniques

Steel alloys are of the most useful materials utilized in the manufacture of various industrial components. In this work, Laser-induced breakdown spectroscopy (LIBS) and spark-induced breakdown spectroscopy (SIBS) techniques have been used as diagnostic tools for the elemental composition of steel alloys and determination of the limit of detection (LOD). Also, the surface hardness of these alloys was measured using the ratio between the Calcium ionic and neutral lines (Ca II/Ca I) as well as the well-known method of mechanical Vickers one. The self-absorption of silicon, copper and calcium lines under investigation was corrected via comparison of the electron densities. The densities have been measured from these lines to that calculated from the hydrogen Hα-line at 656.27 nm which are in the same spectra under the same condition. Calibration curves were achieved for Si and Cu with linear regression coefficients about 0.99 and limits of detection values were 147 and 89 ppm respectively. Also, high accuracy linear relations have been obtained between Vickers mechanical hardness, the ratio between the Calcium ionic and neutral lines (Ca II/Ca I) and the plasma temperature. These results proved the importance of correcting the spectral intensity line for the self-absorption effect before the LOD measurement. Also, they confirmed the correction importance before evaluation of the hardness in LIBS experiments.

Characterization of high microwave power atmospheric pressure plasma torch

An atmospheric pressure microwave plasma torch operating at 2.45 GHz frequency using a surfaguide waveguide fed by argon gas at a constant rate is characterized at various microwave power settings. Coarse optical emission spectroscopy technique is used to diagnose the plasma parameters. The Boltzmann plot method is implemented to measure the electron temperature. Using the Doppler shift of the strong argon atomic spectral lines, the plasma velocity is determined. These results are in good agreement with earlier studies conducted on similar microwave plasma torches at a lower power setting. In this study, we exceed the previous power limitations observed in earlier studies and scan the microwave power in increments up to 2 kW.

Relation between modulation frequency of electric power oscillation during pulse magnetron sputtering deposition of MoNx thin films

This work reports the results of a study, concerning the synthesis of molybdenum nitride thin films, by DC Pulsed Magnetron Sputtering method (PMS), operating with 100 kHz main frequency, and modulated by the additional frequency, adjustable in the range of 10–1000 Hz (modulated Pulse Magnetron Sputtering – mPMS). We have studied the influence of mPMS on the state of plasma using optical emission spectroscopy technique (OES). X-ray photoelectron spectroscopic analysis (XPS) and X-ray diffractometry (XRD) were also used to investigate the relationship between phase composition and modulation frequency of Mo-N thin films. These investigations have revealed a presence of low-temperature phases of β-Mo16N7 and δ-MoN, confirming correlation between chemical state of Mo 3d3/2, 3d5/2 or 3p3/2 and amount of nitrogen incorporation in Mo-N structures. Films’ morphology was well examined by scanning electron microscopy (SEM) and consists the nanocrystalline/amorphous domains. From the utilitarian point of view, very good thermal stability, promising mechanical properties being: H ∼ 16 GPa, E∗ ∼ 180 GPa (NanoTest) and low value of resistivity below 650 μΩcm (4-point probe method) of the Mo-N, predestine them as an effective diffusion barrier in Cu-wired MOSFET structures. Results confirmed that additional modulation frequency should be considered as a significant factor of electric power oscillation during reactive synthesis by means of PMS-based method.

Quantitative analysis of C, Si, Mn, Ni, Cr and Cu in low-alloy steel under ambient conditions via laser-induced breakdown spectroscopy

A diode-pumped solid-state laser (DPSSL) with a high energetic stability and long service life is applied to ablate the steel samples instead of traditional Nd:YAG laser pumped by a xenon lamp, and several factors, such as laser pulse energy, repetition rate and argon flow rate, that influence laser-induced breakdown spectroscopy (LIBS) analytical performance are investigated in detail. Under the optimal experiment conditions, the relative standard deviations for C, Si, Mn, Ni, Cr and Cu are 3.3%–8.9%, 0.9%–2.8%, 1.2%–4.1%, 1.7%–3.0%, 1.1%–3.4% and 2.5%–8.5%, respectively, with the corresponding relative errors of 1.1%–7.9%, 1.0%–6.3%, 0.4%–3.9%, 1.5%–6.3%, 1.2%–4.0% and 1.2%–6.4%. Compared with the results of the traditional spark discharge optical emission spectrometry technique, the analytical performance of LIBS is just a little inferior due to the less stable laser-induced plasma and smaller amount of ablated sample by the laser. However, the precision, detection limits and accuracy of LIBS obtained in our present work were sufficient to meet the requirements for process analysis. These technical performances of higher stability of output energy and longer service life for DPSSL, in comparison to the Q-switch laser pumped by xeon lamp, qualify it well for the real time online analysis for different industrial applications.

Study of the physical discharge properties of a Ar/O2 DC plasma jet

In this paper, the physical properties of plasma discharge in a manufactured DC plasma jet operating with the Ar/O2 gaseous mixture are studied. Moreover, the optical emission spectroscopy technique is used to perform the experimental measurements. The obtained emission spectra are analyzed and, the plasma density, rotational, vibrational and electronic temperature are calculated. The NO emission lines from $$ {\text{NO }}\upgamma \left( {{\text{A}}^{2} {{\Sigma }}^{ + } \to {\text{X}}^{2} {{\Pi }}_{\text{r}} } \right) $$ electronic transition are observed. It is seen that, at the higher argon contributions in Ar/O2 gaseous mixture, the emission intensities from argon ions will increase. Moreover, while the vibrational and excitation temperatures are increased at the higher input DC currents, they will decrease at the higher Ar percentages in the Ar/O2 gaseous mixture. Furthermore, at the higher DC currents and Ar contributions, both the plasma electron density and dissociation fraction of oxygen atoms are increased.

Optical characteristics of a RF DBD plasma jet in various $$\hbox {Ar}/\hbox {O}_{2}$$ Ar / O 2 mixtures

In this paper, using the optical emission spectroscopy (OES) technique, the optical characteristics of a radiofrequency (RF) plasma jet are examined. The $$\hbox {Ar}/\hbox {O}_{2}$$ mixture is taken as the operational gas and, the Ar percentage in the $$\hbox {Ar}/\hbox {O}_{2}$$ mixture is varied from 70% to 95%. Using the optical emission spectrum analysis of the RF plasma jet, the excitation temperature is determined based on the Boltzmann plot method. The electron density in the plasma medium of the RF plasma jet is obtained by the Stark broadening of the hydrogen Balmer $$H_{\beta }$$ . It is mostly seen that, the radiation intensity of Ar 4p $$\rightarrow $$ 4s transitions at higher argon contributions in $$\hbox {Ar}/\hbox {O}_{2}$$ mixture is higher. It is found that, at higher Ar percentages, the emission intensities from atomic oxygen (O) are higher and, the line intensities from the argon atoms and ions including O atoms linearly increase. It is observed that the quenching of $$\hbox {Ar}^{*}$$ with $$\hbox {O}_{2}$$ results in higher O species with respect to $$\hbox {O}_{2}$$ molecules. In addition, at higher percentages of Ar in the $$\hbox {Ar}/\hbox {O}_{2}$$ mixture, while the excitation temperature is decreased, the electron density is increased.

Visualization of gas metal arc welding on globular to spray transition current

ABSTRACTThe transfer modes in gas metal arc welding have important effects on welding quality. However, present study of metal transfer modes is not yet fully understood. In this study, welding arcs was visualised using the optical emission spectroscopy technique. The carbon steel wire electrode was used for welding with 80% Ar + 20% CO2 shielding gas. The results showed that the globular to spray transition current was 330–350 A. During globular to spray transition, argon,CO2 and Fe plasma tended to gradually change from localising near the arc axis to a two-layer structure having 11,000 K in high-temperature region away from the arc axis and around 7000 K in low-temperature region near the arc axis.

Gas Temperature Distribution in Cathode Fall Region of Grimm Glow Discharge

Optical emission spectroscopy technique was used to measure gas temperature along the axis of cylindrical abnormal glow discharge parallel to the copper cathode surface (side-on) in hydrogen-argon mixture at low pressure. The rotational temperature of excited state of H<sub>2</sub> was determined from the rotational structure of Q branch of Fulcher-α diagonal bands using Boltzmann plot technique while the obtained ground vibrational state temperature is assumed to be equal to gas temperature. The temperature T<sub>0</sub> determined from the rotational population density distribution in an excited vibrational state can be considered as a valid estimation of the ground state temperatutre i.e. H<sub>2</sub> gas temperature.

Communication—Detection of Si Distribution in Si/C Composite Anodes by Glow Discharge Optical Emission Spectroscopy

Si/C composite anodes are of great interest for increasing the energy density of Li-ion cells. We report the applicability of the glow discharge optical emission spectroscopy (GD-OES) technique to detect and quantify the Si distribution in Si/C composite anodes. The calibration was developed in the range of 0–100 wt.-% Si by lab coated samples, which are similar to real anodes. The method was verified by pristine real Si/C composite anodes with known compositions (11 wt.-% and 67 wt.-% Si) before being built into cells. Finally, a first attempt of analyzing the Si/C composite anode from a commercial 18650-type cell is presented.

A pulsed plasma jet with the various Ar/N2 mixtures

In this paper, using the Optical Emission Spectroscopy technique, the physical properties of a fabricated pulsed DBD plasma jet are studied. Ar/N2 gaseous mixture is taken as operational gas, and Ar contribution in Ar/N2 mixture is varied from 75 to 95%. Through the optical emission spectra analysis of the pulsed DBD plasma jet, the rotational, vibrational and excitation temperatures and density of electrons in plasma medium of the pulsed plasma jet are obtained. It is seen that, at the wavelength of 750.38 nm, the radiation intensity from the Ar 4p → 4 s transition increases at the higher Ar contributions in Ar/N2 mixture. It is found that, for 95% of Ar presence in the mixture, the emission intensities from argon and molecular nitrogen are higher, and the emission line intensities will increase nonlinearly. In addition, it is observed that the quenching of Ar* by N2 results in the higher intensities of N2 excited molecules. Moreover, at the higher percentages of Ar in Ar/N2 mixture, while all the plasma temperatures are increased, the plasma electron density is reduced.

Electrically-inactive phosphorus re-distribution during low temperature annealing

An increased total dose of phosphorus (P dose) in the first 40 nm of a phosphorus diffused emitter has been measured after Low Temperature Annealing (LTA) at 700 °C using the Glow Discharge Optical Emission Spectrometry technique. This evidence has been observed in three versions of the same emitter containing different amounts of initial phosphorus. A stepwise chemical etching of a diffused phosphorus emitter has been carried out to prepare the three types of samples. The total P dose in the first 40 nm increases during annealing by 1.4 × 1015 cm–2 for the sample with the highly doped emitter, by 0.8 × 1015 cm–2 in the middle-doped emitter, and by 0.5 × 1015 cm–2 in the lowest-doped emitter. The presence of surface dislocations in the first few nanometers of the phosphorus emitter might play a role as preferential sites of local phosphorus gettering in phosphorus re-distribution, because the phosphorus gettering to the first 40 nm is lower when this region is etched stepwise. This total increase in phosphorus takes place even though the calculated electrically active phosphorus concentration shows a reduction, and the measured sheet resistance shows an increase after annealing at a low temperature. The reduced electrically active P dose is around 0.6 × 1015 cm–2 for all the emitters. This can be explained with phosphorus-atoms diffusing towards the surface during annealing, occupying electrically inactive configurations. An atomic-scale visual local analysis is carried out with needle-shaped samples of tens of nm in diameter containing a region of the highly doped emitter before and after LTA using Atom Probe Tomography, showing phosphorus precipitates of 10 nm and less before annealing and an increased density of larger precipitates after annealing (25 nm and less).

Simultaneous Multielemental Analysis of the Leaf of Moringa oleifera by Direct Current Arc Optical Emission Spectroscopy

This study is a methodological work that exploits the utility of direct current arc optical emission spectroscopy technique for the elemental investigation of medicinal plant: the leaf of Moringa oleifera (drumstick). The emission spectrum of the powder sample of the leaf of drumstick plant has been recorded in the spectral region 300–900 nm under optimized experimental conditions and analyzed. The spectrum shows persistent lines of calcium, sodium, potassium, iron, manganese and magnesium with varying intensities thus confirming the presence of these elements in the leaf with different concentration. Intensity and intensity ratio obtained by curve fitting have been utilized for the quantitative estimation of the elements present in the leaf of Moringa oleifera.

OH and O radicals production in atmospheric pressure air/Ar/H2O gliding arc discharge plasma jet

Atmospheric pressure air/Ar/H2O gliding arc discharge plasma is produced by a pulsed dc power supply. An optical emission spectroscopic (OES) diagnostic technique is used for the characterization of plasmas and for identifications of and radicals along with other species in the plasmas. The OES diagnostic technique reveals the excitation Tx ≈ 5550–9000 K, rotational Tr ≈ 1350–2700 K and gas Tg ≈ 850–1600 K temperatures, and electron density under different experimental conditions. The production and destruction of and radicals are investigated as functions of applied voltage and air flow rate. Relative intensities of and radicals indicate that their production rates are increased with increasing content in the gas mixture and applied voltage. reveals that the higher densities of and radicals are produced in the discharge due to more effective electron impact dissociation of and molecules caused by higher kinetic energies as gained by electrons from the enhanced electric field as well as by enhanced The productions of and are decreasing with increasing air flow rate due to removal of Joule heat from the discharge region but enhanced air flow rate significantly modifies discharge maintenance properties. Besides, significantly reduces with the enhanced air flow rate. This investigation reveals that plays a significant role in the production of and radicals.

Detection of laser-produced tin plasma emission lines in atmospheric environment by optical emission spectroscopy technique

A spectroscopic study on laser-produced tin plasma utilizing the optical emission spectroscopy (OES) technique is presented. Plasma is produced from a solid tin target irradiated with pulsed laser in room environment. Electron temperature is determined at different laser peak powers from the ratio of line intensities, while electron density is deduced from Saha-Boltzmann equation. A limited number of suitable tin lines are detected, and the effect of the laser peak power on the intensity of emission lines is discussed. Electron temperatures are measured in the range of 0.36 eV–0.44 eV with electron densities of the order 1017 cm–3 as the laser peak power is varied from 11 MW to 22 MW.

Application of optical emission spectroscopy to high current proton sources

Optical Emission Spectroscopy (OES) represents a very reliable technique to carry out non-invasive measurements of plasma density and plasma temperature in the range of tens of eV. With respect to other diagnostics, it also can characterize the different populations of neutrals and ionized particles constituting the plasma. At INFN-LNS, OES techniques have been developed and applied to characterize the plasma generated by the Flexible Plasma Trap, an ion source used as "testbench" of the proton source built for European Spallation Source. This work presents the characterization of the parameters of a hydrogen plasma in different conditions of neutral pressure, microwave power and magnetic field profile, along with perspectives for further upgrades of the OES diagnostics system.

Development of a Helicon Plasma Source for Neutral Beam Injection System of the Alborz Tokamak

Amirkabir Helicon plasma source (AHPS) has been designed and developed at the fusion laboratory of Amirkabir University of Technology for the neutral beam injection (NBI) system of the Alborz tokamak. The design parameters of the Helicon plasma source are determined to get the $$ n_{e} \cong 10^{19} \,{\text{m}}^{ - 3} $$ plasma density. However, the Nagoya type III antenna was used to excite the Argon plasma by the applied magneto-static field of 750 G and RF power up to 2 kW at the frequency of 13.56 MHz. Preliminary experiments are performed to confirm the Helicon mode operation of the AHPS. Mode changing from the ICP to the Helicon mode was proved by using the optical emission spectroscopy and polaroid photography technique of the plasma “blue core”. Spectroscopy measurements results show that the emission line intensity of the $$ {\text{Ar}}\;{\text{II}} $$ at 434.8 nm increases as the RF power increases in the range of values of 300–1000 W at the neutral background pressure of 0.7 mTorr. Also, we found that, in Helicon mode, the increase of the magneto-static field from 350 to 750 G not only increases the plasma density besides the efficiency of the RF power absorption increases.