Boltzmann Plot Method Research Articles

Qualitative and quantitative discrimination of major elements in Chitosan (natural polymer) using laser induced breakdown spectroscopy

In this work, Laser-Induced Breakdown Spectroscopy (LIBS) is used for qualitative and quantitative analysis of Chitosan samples (natural polymer). For qualitative analysis, plasma parameters are determined, while for quantitative analysis, the initial concentration of chitosan samples is calculated. It developed a plasma plume using a second harmonic (532 nm) laser pulses, which makes the Q-Switched Nd: YAG laser compatible with delay generators and computing electronics. The component elements and their corresponding concentrations are calculated based on the strongest emission lines of the element using the line intensity ratio method and the calibration-free LIBS approach. The results obtained by both methods are compared for the effectiveness of the algorithm.In the chitosan monomer (C6H11NO4)n, four major elements (hydrogen, carbon, nitrogen and oxygen) were detected and their quantities were calculated. In addition to investigating the physical behavior of plasma in the interaction of laser beams with materials, the plasma parameters (electron number density and plasma temperature) are determined by stark-broadening profile fitting and Boltzmann plot method, respectively. The results obtained show that the LIBS can be exploited for quantitative and standard analysis of industrial grade materials for better results in applications.

Elemental analysis of talcum powder using spectroscopic techniques

Talcum powder is a much more useable cosmetic in many parts of the globe. It is responsible for harmful chemical poisoning such as it is likely to promote cancer symptoms. Due to the dangerous effect of harmful chemicals, talcum powder was analyzed. We report the elemental composition of the talcum powder using spectroscopic techniques, plasma has been produced at an atmospheric air pressure using a Q-switch (1064 nm) Nd: YAG laser with a laser intensity of 1.9 × 1011 W/cm2, 10 Hz repetition rate, and 5 ns pulse duration. From the spectroscopic analysis of the recorded spectra of plasma, we have detected Ca, Mg, Cr, Na, Sr, Li, and H. electron temperature (Te) has been calculated using the Boltzmann plot method while electron number density (Ne) calculated using the Stark Broadening profile method. Besides that, we have studied the behavior of Te and Ne as a function of delay time. It was observed the decreasing trends of the plasma parameters with delay time. The Inverse Bremsstrahlung (IB) absorption co-efficient and its fluctuation over delay time were also determined.We have also studied the elemental composition of the talcum powder using CF-LIBS, AAS, and EDX techniques. It was also noticed the maximum concentration of Ca in talcum powder using CF-LIBS, AAS, and EDX techniques.

Analysis of an Iron-Copper Alloy by Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS)

The purpose of the present work was to monitor the reliability of the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) by comparing the results with inductively coupled plasma - mass spectrometry (ICP-MS). For the laser ablation studies, the plasma was generated by a Q-switched Nd: YAG laser, and the emission spectra of the alloy sample were recorded using a set of Avantes spectrometers covering the wavelength region from 250 to 870 nm. Optical emission spectra confirmed that copper and iron are the major constituents while traces of sodium and magnesium were also observed. The Boltzmann plot method was employed to calculate the plasma temperature to be (8400 to 8700) ± 1000 K using the neutral lines of iron and copper. The electron number density was calculated using the Stark broadened line profiles of the neutral copper lines to be (2.2 ± 0.2) × 1016 cm−3. The relative compositions of iron and copper were determined to be 23.85 ± 5% and 76 ± 5% using CF-LIBS. To validate the method, the composition of the alloy was also determined using inductively coupled plasma – mass spectrometry (ICP-MS) and the results were excellent agreement with those by CF-LIBS. This study demonstrated that CF-LIBS is a powerful and reliable tool for quality control of alloys.

Spectroscopic analysis of the arc plasma during activating flux tungsten inert gas welding process

A-TIG welding has been widely used in the manufacturing fields of aerospace, pressure vessels and ships as a highly efficient welding method. However, the mechanism of the effect of the activating flux on the arc behavior is still controversial. In this work, the spatial distribution of A-TIG welding arc spectra under the action of three types of active agents (fluorides, oxides and chloride) was studied using a spectral diagnostic method. The distribution characteristics of active agent particles, argon and iron particles in the arc were analyzed as well as the arc electron temperature was calculated using Boltzmann plot method. The experimental results shown that the distribution state of different active particles in the spatial of the arc is different. The influence of different active agents on the arc electron temperature in the spatial area of the arc is inconsistent. Chloride can cause a significant increase in the whole arc temperature. Fluoride can increase the arc electron temperature near the anode area. Oxide has less effect on the overall arc temperature.

Importance of physical units in the Boltzmann plot method

Dimensional analysis of the Boltzmann plot equation used to determine the temperature in a laboratory plasma.

Diagnosis of lightning return stroke channel temperature according to different band spectra

The spectral data of a lightning discharge process are captured by a high-speed slit-less grating spectrograph. Based on the plasma spectrum theory, the lightning return stroke channel temperature is estimated according to the spectral information of the different bands. The results show that the average temperatures of the lightning return stroke channel estimated by the Boltzmann plot method are 43270, 17660 and 17730 K, respectively, when the spectral line group of the single ionized nitrogen atom (NII), neutral oxygen atom (OI) and neutral nitrogen atom (NI) are selected respectively. The average temperature of the lightning return stroke channel is 24770 K, which is estimated based on the Saha-Boltzmann plot method by using NII and NI spectral line groups. Based on the lightning channel corona sheath model and the spectral radiation theory, it can be inferred that the temperature obtained by using only NII spectral line group should be the temperature of the lightning return stroke channel core, and the temperature obtained by using only NI or OI spectral line group should be the temperature of the corona sheath around the lightning return stroke channel core. Using both NII and NI spectral line groups, the obtained temperature should be the average temperature of the entire channel section (including the channel core and corona sheath) in the exposure time.

Influence of the Distance between Focusing Lens and Target Surface on the Characteristics of Laser-excited Lead Plasma

The present work investigated the effect of distance from target surface on the parameters of lead plasma excited by 1064nm Q-switched Nd:YAG laser. The excitation was conducted in air, at atmospheric pressure, with pulse length of 5 ns, and at different pulse laser energies. Electron temperature was calculated by Boltzmann plot method based on the PbI emission spectral lines (369.03 nm, 416.98 nm, 523.48, and 561.94 nm). The PbI lines were recorded at different distances from the target surface at laser pulse energies of 260 and 280 mJ. The emission intensity of plasma increased with increasing the lens-to-target distance. The results also detected an increase in electron temperature with increasing the distance between the focal lens and the surface of the target in all laser energies under study. In addition, the electron number density was determined by using the Stark broadening method. The data illustrated that the electron number density was increased with increasing the distance from target surface, reaching the maximum at a distance of 11 cm for all pulse laser energy levels under study.

Self-absorption effect in calibration-free laser-induced breakdown spectroscopy: Analysis of mineral profile in Maerua oblongifolia plant

Maerua oblongifolia is a traditional medicinal plant served for health advancing effects due to rich nutrients. The compositional analysis of this plant was carried out using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS). The laser-produced plasma was generated on the pelletized samples of roots, stem, leaves, and fruits to record and analyze the corresponding emission spectra. The spectroscopic analysis revealed the presence of elements such as Na, Ca, Mg, K, Al, Fe, Li, Si, Sr, Zn, Ba, and Rb. As a prerequisite of quantitative analysis, and for the determination of reliable plasma parameters, a simplified approach was used to correct the self-absorption in the emission lines to determine the plasma temperature using Boltzmann and Saha-Boltzmann plot methods. This procedure was further used to develop the modified Saha-Boltzmann plot, which uses the columnar densities of emitting species at the ground state to determine the plasma temperature. Finally, the one-line CF-LIBS was used to quantify the concentration of all the perceived constituent elements. LIBS results were cross-validated with that obtained from ICP-MS.

The role of nanoparticles concentration in the emission intensity enhancement of the laser-produced aluminum plasma

The nanoparticles-enhanced Laser-Induced Breakdown Spectroscopy (NELIBS) is an attractive technique to achieve the emission intensity enhancement of the LIBS spectrum. In this article, we present a study on the enhancement in the LIBS signals of seven different aluminum spectral lines using silver (Ag) nanoparticles on the surface of the Al target. The intensity enhancement factor of about 2–8 as compared with the conventional LIBS has been realized. The results showed an increase in the enhancement factor with the increasing concentration of the Ag nanoparticles. Plasma parameters, such as excitation temperature was estimated using the Boltzmann plot method whereas, the electron number density was estimated from the Stark broadened Al I lines. An increase in the excitation temperature and electron number density has been observed in NELIBS as compared with the conventional LIBS. Furthermore, the relative concentration of the neutral aluminum atoms estimated from the Boltzmann plot is found to be higher in NELIBS as compared with conventional LIBS. The presence of silver nanoparticles resulted in a better interaction of the laser beam with matter revealing enhanced emission intensity.

Determination of Electron Temperature of Pulsed Washer Gun–Generated Argon Plasma by Corona Model

The pulsed washer gun–generated plasma released into an evacuated chamber has been diagnosed using the spectroscopic technique. By analyzing the recorded spectral lines of argon plasma, the electron temperature is determined using the spectral line ratios of the Ar ion and Ar atom following the Corona model. The light is collected using an optical fiber placed at a glass port of the chamber and fed into a digital spectrometer to obtain the emitted spectra from plasma in front of the plasma gun mouth. As the plasma diffuses after ejecting out into the evacuated chamber from the plasma gun, the Corona model is an appropriate model for the electron temperature estimation. Large differences in estimated electron temperatures are observed when the Boltzmann plot method, assuming the local thermal equilibrium model for the atomic and ionic lines separately, is used. To study the effect of base pressure in the evacuated chamber on the electron temperature of the plasma ejecting out of the gun, the electron temperature with different base pressures ranging from 20 to 100 Pa is measured and analyzed.

Single-shot spatial-resolved optical emission spectroscopy of argon and titanium species within the spoke

The rotating plasma patterns, also known as ionisation zones or spokes, observed, among other discharges, in high power impulse magnetron sputtering discharge (HiPIMS) require non-invasive diagnostics favourable for a precise characterisation of their properties. In this contribution, the single-shot spatial-resolved optical emission spectroscopy of the spoke was conducted in non-reactive HiPIMS discharge using a titanium target. Investigated working pressures cover the conditions with the presence of localised, well-defined spokes. A fast photodiode and a cylindrical Langmuir probe were utilised to capture and determine the passing spoke position. These signals were synchronised with the acquisition of the optical emission spectrum by the intensified charge-coupled device detector. A large amount of single-shot data enabled the statistical analysis of the spoke. The optical emissions of argon atoms and ions and titanium atoms and ions were investigated in the passing spoke. It was found that the intensities of the spectral lines of the Ar and Ti species have the characteristic evolution for all studied spectral lines of this specific species within the spoke. The intensity evolutions are independent of the applied pressure. The evolution of the excitation temperatures determined by the Boltzmann plot method using the Ar II and Ti I and Ti II spectral lines remains constant within the spoke in the margin of standard error for all investigated pressures.

Optical Characterization of Stabilized Atmospheric Pressure Pin to Plate Plasma Source

DC Stabilized Discharges (DCSD) was generated in atmospheric pressure argon for a pin to plate. In this paper, discharge with a flowing argon gas into the air (plasma Source) is investigated by optical emission spectroscopy technique. The emission spectra of excited species of atomic-hydrogen, N2 and Ar were observed and measured. The rotational and vibrational temperatures of the discharge were measured by comparing modelled optical emission spectra with masured spectra from the discharge by using several different vibrational bands of the 2nd positive system (SPS) of N2 ( N2[C 3Πu] → N2[B 3Πg]). The optical characteristics of the discharge shown that the DCSD was found to be non-equilibrium with rotational temperature (Tr) of 1087 K and vibrational temperature (Tv) of 1661 K. Boltzmann plot method has been applied to estimate the electronic excitation temperature which was found to be 1.36 eV and 1.1 eV for discharges with argon flow rates of 1.0 SLM & 0.5 SLM respectively. This finding proved the strong non-equilibrium nature of the discharge conditions of the current work.

Temperature estimation using Boltzmann plot method of titanium emission lines produced on electric arc discharge

Temperature is an important characteristic in electric arc discharge processes for physical vapor deposition treatments. In this work, a titanium cathode was used and, by identifying the spectral emission lines in the range 300 nm −550 nm, it was possible to determine by means of the Boltzmann graphical method the temperature of the plasma generated in specific areas of the cathode surface during the discharge process of Arc. As a result, the estimated temperature has close values for the different emission lines (T i +, T i ++, and T i +++) with uncertainties lower than 10%.

Spectroscopic Diagnosis of the CdO:CoO Plasma Produced by Nd:YAG Laser

In this paper, the optical emission spectrum (OES) technique was used to analyze the spectrum resulting from the (CdO:CoO) plasma in air, produced by Nd:YAG laser with λ=1064 nm, τ=10 ns, a focal length of 10 cm, and a range of energy of 200-500 mJ. We identified laser-induced plasma parameters such as electron temperature (Te) using Boltzmann plot method, density of electron (ne), length of Debye (λD), frequency of plasma (fp), and number of Debye (ND), using two-Line-Ratio method. At a mixing ratio of X= 0.5, the (CdO:CoO) plasma spectrum was recorded for different energies. The results of plasma parameters caused by laser showed that, with the increase in laser energy, the values of Te, ne and fp were increased, while the value of λD was decreased. The calculated electron temperature value was in the range of 0.449-0.619 eV at ratio X=0.5

Development of laser induced breakdown spectroscopy technique to study irrigation water quality impact on nutrients and toxic elements distribution in cultivated soil.

This study is focused mainly on impact of irrigation water quality in cultivated soil on distribution of essentials nutrients (Al, Mg, Ca, Fe, S, Si, Na, P, and K) and relatively toxic metals (As, Ba, Cr, Cu, Ti, Sn, Mn, Ni, and Zn) using an elegant Laser induced breakdown spectroscopy (LIBS) technique. A pulsed Nd:YAG laser operating at 1064 nm in conjunction with suitable detector was applied to record soil emission spectra. The abundance of these elements were evaluated via standard calibration curve Laser Induced Breakdown Spectroscopy (CC-LIBS) and calibration free Laser Induced Breakdown Spectroscopy (CF-LIBS) approaches. Quantitative analyses were accomplished under conjecture of local thermodynamic equilibrium (L.T.E) and optically thin plasma. The average electron temperatures were estimated by Boltzmann plot method for cultivated soil samples in 7800 to 9300 K range. The electron number density was ~ 1.11 × 1017 cm − 3 to 1.60 × 1017 cm − 3. Prior to application on soil samples, the experimental setup was optimized at the following parameters: pulsed energy = 60 mJpulse-1, sample to lens distance of 9.0 cm, and the gate delay of 3.5 μs. It is noteworthy that nutritional elements content of cultivated soils were found strongly dependent upon the irrigation water quality. The cultivated soil from industrial area was found rich of toxins while the cultivated land using tube well water contains toxins in least amount. Our LIBS findings were also validated by comparing its results with contents measured using a standard inductively coupled plasma optical emission spectroscopy (ICP-OES) method and both were found in excellent agreement. The present study could be highly beneficial for agricultural applications and for farmers to produce safe food products and higher crops yield.

Diagnostics of zinc selenite plasma produced by FHG of a Q-switchedND: YAGlaser

We presented the OES studies of the Zinc Selenite ZnSe plasma produced by the FHG (1064nm) of a Q-switched ND: YAG laser. The target material was placed in front of laser beam in air at atmospheric pressure. the experimentally observed line profiles of zinc (ZnI) have been used to extract the Te using the Boltzmann plot method. Whereas, the ne has been determined from the Stark broadening method using the Zinc (Zn I) line. And it is calculated ωp, λd and Nd. The Te is calculated by varying the laser energy at (100, 200, 300, 400 and 500) mJ. It is observed that Te , ne and ωp increases as laser energy is increased while λd and Nd decreases as laser energy increased.

Qualitative and quantitative analysis of steatite using calibration-free laser-induced breakdown spectroscopy in conjunction with x-ray fluorescence spectroscopy and Fourier-transform infrared spectroscopy.

The qualitative and quantitative study of raw steatite was carried out using a pulsed nanosecond Nd:YAG laser set to fundamental harmonic (1064 nm) at atmospheric pressure. To cross-validate the data, x-ray diffraction (XRD), x-ray fluorescence (XRF) spectroscopy, and Fourier-transform infrared spectroscopy (FTIR) were used. The analysis of optical emission spectra in the wavelength range 200-720 nm showed the existence of silica (Si), magnesium (Mg), and calcium (Ca). The plasma temperature and electron number density were estimated using the Boltzmann plot and Stark-broadening line profile methods, with results at 4906 K and ${1.47}\times{{10}^{17}}\;{{\rm cm}^{- 3}}$, respectively. The quantitative study was carried out using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) process, assuming local thermodynamic equilibrium and an optically thin plasma, and the following results were obtained: Si = 63.37%, Mg = 35.95%, and Ca = 0.671%. The quantitative findings obtained using the CF-LIBS approach were consistent with those obtained using XRD, XRF, and FTIR, demonstrating the applied methods' potential to be effective and complementary for the qualitative and quantitative study of multiphase raw steatite.

Cold Atmospheric Pressure Plasma Technology for Modifying Polymers to Enhance Adhesion: A Critical Review

This review summarizes the results of cold atmospheric pressure plasma technology application in polymers surface treatment. Attention is given to results of changes in the hydrophilic property of polymer surfaces by incorporation of polar functional groups when exposed to atmospheric pressure plasma, depending on the time of treatment, applied voltage, gas flow rate, and distance from the surface. We have successfully developed a plasma device that is able to generate cold atmospheric pressure argon plasma of low temperature (20 – 26) ° C downstream using a high-voltage power source which can be widely used in materials processing. Therefore, a cost-effective system of generating a plasma jet at atmospheric pressure with potential applications has been developed. Cold atmospheric pressure plasma jet (CAPPJ) has shown a lot of applications in recent years such as in materials processing, surface modification, and biomedical materials processing. CAPPJ has been generated by a high voltage (0-20 kV) and high frequency (20-30 kHz) power supply.<br/> The discharge has been characterized by optical and electrical methods. In order to characterize cold atmospheric pressure argon plasma jet, its electron density, electron temperature, rotational temperature, and vibration temperature have been determined using the power balance method, intensity ratio method, Stark broadening method, and Boltzmann plot method, respectively. The improvement in hydrophilicity of the cold plasma-treated polymer samples was characterized by contact angle measurements, surface free energy analysis, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Contact angle analysis showed that the discharge was effective in improving the wettability of polymers after the treatment. Furthermore, atmospheric plasma can be effectively used to remove surface contamination and to chemically modify different polymer surfaces. The chemical changes, especially oxidation and cross-linking, enhance the surface properties of the polymers.

Spectroscopic evaluation of vibrational temperature and electron density in reduced pressure radio frequency nitrogen plasma

The optical emission spectroscopy technique is used to determine the vibrational temperature of the second positive band system, N_{2} (C,upsilon^{^{prime}} - B,upsilon^{^{primeprime}}) in the wavelength range 367.1–380.5 nm by using the line-ratio and Boltzmann plot methods. The electron temperature is evaluated from the intensity ratio of the selected molecular bands corresponding to N_{2}^{ + } (B,upsilon - X, upsilon^{^{prime}} , 391.44 nm), and, N_{2} (C,upsilon^{^{prime}} - B,upsilon^{^{primeprime}}, 375.4 nm) transitions, respectively. The selected bands have a different threshold of excitation energies and thus serve as a sensitive indicator of the electron energy distribution function (EEDF). The electron density has been determined from the intensity ratio of the molecular transitions corresponding to N_{2}^{ + } (B,upsilon - X, upsilon^{^{prime}} , 391.44 nm), and, N_{2} (C,upsilon^{^{prime}} - B,upsilon^{^{primeprime}}, 380.5 nm) for different levels of pressure and radio frequency power. The results show that the vibrational temperature decreases with increasing nitrogen fill pressure and radio frequency power. However, the electron temperature increases with radio frequency power and reduces with fill pressure. The electron density increases both with nitrogen fill pressure and radio frequency power that attributes to the effective collisional transfer of energy producing electron impact ionization. Plasma parameters show a significant dependence on discharge conditions and can be fine-tuned for specific surface treatments.Article HighlightsSpectrum analysis of RF-driven nitrogen plasma for varying discharge conditionsEvaluation of vibrational temperature using line-ratio and Boltzmann plot methodsComparison of vibrational temperatures for line-ratio and Boltzmann plot methodsEvaluation of electron temperature and density using the intensity-ratio of bandsCorrelation of temperature and density with varying fill pressure and RF power

Spectroscopic Investigation of Laser-Produced Strontium Plasma Using Fundamental and Second Harmonics of Nd:YAG Laser

In the present work, our main focus is to find out an optical window where the plasma is optically thin and the plasma parameters can be determined more reliably. The strontium plasma was generated using the fundamental (1064 nm) and the second harmonic (532 nm) of a Q-switched Nd:YAG laser. The spectra were registered using a set of five miniature spectrometers covering the spectral range from 200 to 720 nm. The intensity ratios of some specific lines have been compared with the theoretically calculated intensities to check the validity of optically thin plasma, free from self-absorption and in local thermodynamic equilibrium. In the selected optical window, the electron number densities have been determined from the Stark broadened line profiles, and the excitation temperatures have been calculated using the Boltzmann plot method for 1064- and 532-nm laser wavelengths. The variations in the electron number density and excitation temperature have been studied as a function of laser energy (8-100 mJ), atmospheric pressure (100-600 mbar), and spatial distribution of the plasma plume (0.5-4.0 mm) for both the lasers. The electron number density is found to be higher for the 532-nm laser than the 1064-nm laser, while the excitation temperature is higher for the 1064-nm laser than the 532-nm laser. We have fitted a power law on the experimental data to analyze the varying trends of excitation temperature.