Stark-broadened Line Profiles Research Articles

Optical and thermal characterization of pure CuO and Zn/CuO using laser-induced breakdown spectroscopy (LIBS), x-ray fluorescence (XRF), and ultraviolet–visible (UV–Vis) spectroscopy techniques

We present elemental analysis and thermal characterization of pure and two different concentrations of zinc-doped copper oxide (CuO) samples using different analytical techniques. The quantitative as well as qualitative investigations, were performed by incorporating calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique. The plasma was generated on the samples surface by focusing a first harmonic of Nd: YAG laser of 1064 nm wavelength and the time-integrated emission spectra was achieved through a set of five spectrometers equipped with a charge-coupled-device. The acquired optical emission spectra from laser-generated plasma show different concentrations of zinc and copper in different samples which are consistent with their percentage composition measured during the sample synthesis. Using LIBS emission analytical lines, the Boltzmann technique was utilized for estimating the excitation temperature, while the number density was evaluated using the well-known Stark broadening line profile method. Besides, the CF-LIBS elemental analysis was validated by the x-ray fluorescence technique. For the optical study, ultraviolet–visible spectroscopical analysis was performed to find the bandgap of pure and zinc-doped copper oxide samples and consequently, variation in bandgap was studied with the growth of zinc doping. In addition, the thermal properties of the samples were analyzed using the beam deflection spectroscopy technique. The results shows that thermal diffusivity () and thermal conductivity (), increased with an increase in zinc concentration.

Chemometrics and Spectroscopic Analyses of Peganum harmala Plant’s Seeds by Laser-Induced Breakdown Spectroscopy

In the present work, the rapid identification of elements and their relative chemical composition in various Peganum harmala seed samples were investigated using a calibration-free laser-induced breakdown spectroscopy technique (CF-LIBS). A pulsed Nd:YAG laser-source with a 5 ns pulse-duration, and 10 Hz pulse repetition rates providing 400 and 200 mJ energy at 1064 and 532 nm wavelength, respectively, was focused on the Peganum harmala seed samples for ablation. A LIBS 2000+ spectrometer within the wavelength range (200 to 720 nm), emission-spectra were recorded. The measured spectra of the Peganum harmala sample gives spectral lines of Carbon (C), Magnesium (Mg), Lithium (Li), Sodium (Na), Calcium (Ca), Silicon (Si), Iron (Fe), Strontium (Sr), Copper (Cu), Potassium (K), and Lead (Pb). A CF-LIBS technique has been employed for the compositional study of the elements exist in the Peganum harmala seed samples. The measured results demonstrate that C, Mg, and Ca are found to be major elements in the Peganum harmala seed samples with compositions of ~36.64%, ~24.09%, and ~19.03%, respectively. Along with the major elements, the elements including Li, Na, Si, K, Fe, and Sr were identified as minor elements with compositions of ~2.87%, ~2.33%, ~3.72%, ~7.17%, ~2.83%, and ~1.14%, respectively. Besides Cu (~8.07 μg/g), and Pb (~1.10 μg/g) elements were observed as trace elements exist in the Peganum harmala seed samples. Furthermore, the electron number density including the plasma excitation-temperature were calculated using the stark-broadening line profile method and the Saha–Boltzmann plot method, respectively. The plasma parameters versus laser-irradiance and the distance from the sample were further investigated. Moreover, a principal component analysis (PCA) method was also utilized to the spectral data obtained by using LIBS to discriminate various seed samples with four classes, namely, α, β, γ, and Δ. Three principal-components (PCs) calculated from eigenvalues of score matrix described 87.6%, 4.6%, and 2.5% of total variance for PC1, PC2, and PC3, respectively. The LIBS spectral data variance covered by the initial 3 PCS was found as ~94.7% of total variance. The PCA results have successfully demonstrated the different classes of the Peganum harmala seed samples based on the different doping compositional ratios of the Zn element. This study confirmed the feasibility and ability of LIBS and PCA for the rapid analysis of Peganum harmala seed samples. Finally, the results achieved using CF-LIBS were incorporated with those obtained from the XRF and EDX analytical techniques.

Quantification of Aluminum Gallium Arsenide (AlGaAs) Wafer Plasma Using Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS).

In this work, we report the results of the compositional analysis of an aluminum gallium arsenide (AlGaAs) sample using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique. The AlGaAs sample was doped with three various concentrations of gallium (Ga), arsenic (As), and aluminum (Al), as reported by the manufacturer, and the CF-LIBS technique was employed to identify the doping concentration. A pulsed Q-switched Nd: YAG laser capable of delivering 200 and 400 mJ energy at 532 and 1064 nm, respectively, was focused on the target sample for ablation, and the resulting emission spectra were captured using a LIBS 2000+ spectrometer covering the spectral range from 200 to 720 nm. The emission spectra of the AlGaAs sample yielded spectral lines of Ga, As, and Al. These lines were further used to calculate the plasma parameters, including electron temperature and electron number density. The Boltzmann plot method was used to calculate the electron temperature, and the average electron temperature was found to be 5744 ± 500 K. Furthermore, the electron number density was calculated from the Stark-broadened line profile method, and the average number density was calculated to be 6.5 × 1017 cm−3. It is further observed that the plasma parameters including electron temperature and electron number density have an increasing trend with laser irradiance and a decreasing trend along the plume length up to 2 mm. Finally, the elemental concentrations in terms of weight percentage using the CF-LIBS method were calculated to be Ga: 94%, Al: 4.77% and As: 1.23% for sample-1; Ga: 95.63%, Al: 1.15% and As: 3.22% for sample-2; and Ga: 97.32%, Al: 0.69% and As: 1.99% for sample-3. The certified concentrations were Ga: 95%, Al: 3% and As: 2% for sample-1; Ga: 96.05%, Al: 1% and As: 2.95% for sample-2; and Ga: 97.32%, Al: 0.69% and As: 1.99% for sample-3. The concentrations measured by CF-LIBS showed good agreement with the certified values reported by the manufacturer. These findings suggest that the CF-LIBS technique opens up an avenue for the industrial application of LIBS, where quantitative/qualitative analysis of the material is highly desirable.

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.

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.

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.

Stark-Broadening of Ar K-Shell Lines: A Comparison between Molecular Dynamics Simulations and MERL Results

Analysis of Stark-broadened spectral line profiles is a powerful, non-intrusive diagnostic technique to extract the electron density of high-energy-density plasmas. The increasing number of applications and availability of spectroscopic measurements have stimulated new research on line broadening theory calculations and computer simulations, and their comparison. Here, we discuss a comparative study of Stark-broadened line shapes calculated with computer simulations using non-interacting and interacting particles, and with the multi-electron radiator line shape MERL code. In particular, we focus on Ar K-shell X-ray line transitions in He- and H-like ions, i.e., Heα, Heβ and Heγ in He-like Ar and Lyα, Lyβ and Lyγ in H-like Ar. These lines have been extensively used for X-ray spectroscopy of Ar-doped implosion cores in indirect- and direct-drive inertial confinement fusion (ICF) experiments. The calculations were done for electron densities ranging from 1023 to 3×1024 cm−3 and a representative electron temperature of 1 keV. Comparisons of electron broadening only and complete line profiles including electron and ion broadening effects, as well as Doppler, are presented. Overall, MERL line shapes are narrower than those from independent and interacting particles computer simulations performed at the same conditions. Differences come from the distinctive treatments of electron broadening and are more pronounced in α line transitions. We also discuss the recombination broadening mechanism that naturally emerges from molecular dynamics simulations and its influence on the line shapes. Furthermore, we assess the impact of employing either molecular dynamics or MERL line profiles on the diagnosis of core conditions in implosion experiments performed on the OMEGA laser facility.

Determination of base metals and gold in Pb-Sb sulfosalt mineral boulangerite using laser-induced breakdown spectroscopy and inductively coupled plasma optical emission spectrometry

Gold (Au) is an economically important metal. Its determination is a challenging and crucial task due to its presence in low concentration and heterogeneous distribution in gold-bearing minerals. The suitability and performance of laser-induced breakdown spectroscopy (LIBS) to identify base and precious metals, especially gold, in a boulangerite sample was evaluated. X-ray diffractometer phase analysis was carried out to determine constituent phases, revealing the presence of boulangerite, tridymite and galena. Analysis of the optical emission spectra obtained on the boulangerite surface using a Q-switched Nd:YAG laser at a fundamental harmonic (1064 nm) in the 200–720 nm spectral range revealed the presence of Pb, Sb, S, Au, Cu, Ca, Fe, Mn, Zn, Si, Mg, Al, Na, Ni and Li. Most of the emission lines for the major elements constituting boulangerite (Pb, Sb and S) were observed in the shorter wavelength region. The resonance line of Au appearing at 242.79 nm and corresponding to the 5d106p2P3/2 → 5d106s2S1/2 transition facilitated its identification. The plasma temperature was calculated by the Boltzmann plot method using neutral Au lines which resulted as 11 295 ± 1100 K. A more accurate method known as the Saha–Boltzmann plot method was also employed to strengthen the plasma temperature calculation with good agreement. The electron number density was estimated using the Stark-broadened line profile of the neutral silica line at 288.15 nm and was found to be 7.63 × 1017 cm−3. The laser-generated plasma on the boulangerite surface was optically thin and fulfilled the local thermodynamic equilibrium condition. The LIBS compositional analysis results were cross-validated using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy, inductively coupled plasma optical emission spectroscopy and Fourier-transform infrared spectroscopy, revealing an analogous composition. The results obtained using LIBS and other techniques displayed their ability as powerful and complementary tools for the compositional analysis of base and precious metals, especially gold, in gold-bearing minerals.

Elemental analysis of sage (herb) using calibration-free laser-induced breakdown spectroscopy.

In this work, laser-induced breakdown spectroscopy (LIBS) has been used for the quantitative and qualitative analysis of the sage sample using the calibration-free LIBS (CF-LIBS) technique. The sage plasma is generated by focusing the second harmonics (532 nm) of a Q-switched Nd:YAG laser with a repetition rate of 10 Hz and pulse duration of 5 ns. The emission spectra are recorded using a LIBS 2000 detection system spectrometer consisting of five high-resolution spectrometers covering a wavelength range from 200 to 720 nm. The optical emission spectra of the sage sample reveal the spectral lines of Fe, Ca, Ti, Co, Mn, Ni, and Cr. The plasma temperature and electron number density of the neutral spectral lines of the pertinent elements have been deduced using the Boltzmann plot and Stark-broadening line profile method, with average values 8855±885K and 3.89×1016cm-3, respectively. The average values of the plasma parameters were used for the quantification of the detected elements in the sample. Based on the calibration-free method, the measured results demonstrate that Fe is the major constituent in the sample, having a percentage concentration of 48.1%, while the remaining elements are Ca, Ti, Co, Mn, Ni, and Cr, with percentage concentrations 0.7%, 5.3%, 8%, 11%, 12.3%, and 14.6%, respectively. This study demonstrates the feasibility of LIBS for the compositional analysis of major and trace elements present in the plant samples and its further applications in medicine.

Quantitative analysis of saindha salt using laser induced breakdown spectroscopy and cross-validation with ICP-MS

Saindha salt is considered to be more advantageous than the other edible salts for the patients suffering from diabetes, blood pressure and kidney diseases. To explore the constituent elements of this salt, laser induced breakdown spectroscopy (LIBS) has been exploited for its qualitative and quantitative analysis. The third harmonic (355 nm) of a Q-switched Nd:YAG laser has been used to produce the saindha salt plasma and the time integrated optical emission spectra were registered using a set of six miniature spectrometers covering the spectral range of 230–805 nm. The spectroscopic analysis of the emission spectra predominately revealed numerous neutral or singly ionized emission lines of Ca, Mg, Na, K, Fe, Sr, Si, Li and Al. The laser produced plasma was characterized by calculating the electron temperature from the Boltzmann plots and the electron number density from the Stark broadened line profile as a function of laser irradiance and distance from the target sample. The relative concentration of the constituent elements was extracted by the integrated line intensities of the strongest spectral line of each element using the self-calibration-LIBS (SC-LIBS) and one-line calibration free-LIBS (OLCF-LIBS) methods. For cross-validation, the LIBS results have been compared with that obtained from the inductively coupled plasma-mass spectroscopy (ICP-MS) showing good agreement.

Plasma Diagnostic by Optical Emission Spectroscopy on Dolomite and Cross-Validation Using Scanning Electron Microscopy Coupled with Energy Dispersive X-ray Spectroscopy and Electron Probe Micro-Analysis

Dolomite [CaMg(CO3)2] is an important carbonate mineral mainly composed of calcium magnesium carbonate. The correct determination of magnesium content in carbonate rocks is important for accessing its suitability for different applications; however, presence of different phases with varying magnesium contents makes their analysis difficult. In the present work, a natural carbonate mineral dolomite is analyzed qualitatively and quantitatively using laser-induced breakdown spectroscopy along with X-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy and electron-probe microanalysis. The optical emission spectra recorded in 200–720 nm wavelength region revealed presence of emission lines for Ca, Mg, Al, Sr, and Na with varying intensities. We used two different techniques, that is, Boltzmann plot and Saha–Boltzmann plot methods to calculate the plasma temperature, and an average value of 4500 ± 450 K was deduced.The Stark broadening line profile method was exploited to calculate the electron number density using calcium and magnesium lines which resulted in 2.39 × 1017 cm–3. The quantitative compositional analysis was carried out using calibration-free laser-induced breakdown spectroscopy method for which the local thermodynamic equilibrium and optically thin plasma conditions were satisfied.The composition for dolomite major constituents calcium and magnesium were estimated as 68.58 and 31.41%, respectively.The results demonstrated the LIBS, EDS, and EPMA ability as an effective, powerful and complementary analytical techniques for the elemental composition analysis of carbonate minerals.

Quantitative elemental analysis of high silica bauxite using calibration-free laser-induced breakdown spectroscopy.

Bauxite is a primary ore of aluminum. Precise information about bauxite mineralogical composition is challenging and crucial for efficient aluminum extraction and for the determination of its appropriateness for different industrial applications. For the qualitative and quantitative analysis of bauxite ore, we performed laser-induced breakdown spectroscopy (LIBS) in conjunction with x-ray diffraction (XRD), x-ray fluorescence spectroscopy (XRF), scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM-EDS), and Fourier transform infrared spectroscopy (FTIR). Analysis of the acquired optical emission spectrum revealed the presence of Si, Al, Fe, K, Ti, Ca, Mg, Na, Cr, and Sr. The plasma temperature and electron number density values estimated using Boltzmann plot and Stark-broadening line profile methods were 5600K and 7.65×1017 cm-3, respectively. In the present study we show that a calibration-free LIBS method presents a powerful solution, enabling quantitative analysis of multi-element bauxite ore better than traditional analytical techniques. The bauxite quantification obtained using CF-LIBS under the assumption of local thermodynamic equilibrium and optically thin plasma was Si=47.31%, Al=31.90%, Fe=16.54%, K=2.45%, Ti=1.64%, and Ca=0.16%, and its comparison with the outcome from XRD, XRF, SEM-EDS, and FTIR not only assisted but potentially enhanced the mineralogical composition understanding of bauxite ore in the present study.

Detection of Nutrition and Toxic Elements in Dry Milk Powders Available in Pakistan Using Laser Induced Breakdown Spectroscopy

In this work, qualitative as well as the quantitative study of nutritional and trace toxic metals in various dry milk powders (local and branded) available in Pakistan was accomplished by calibration free-laser induced breakdown spectroscopy (CF-LIBS). To analyze the optical emission spectra, a pulsed Nd-YAG laser was utilized to produce micro-plasma on the surface of samples. The emitted light was acquired with a dedicated spectrometer for subsequent analysis and quantification of the species in the target. Ca, K, Mg, Na, P, Zn, Al, and S were identified as nutritional elements, while Cd, Cr, Cu Mn, and Ni as heavy metals. Our LIBS system was optimized by parametric dependence study. The average plasma temperatures were estimated using Boltzmann plot method for all types of milk powder between 8000 and 95,000 K. The electron number density was determined from the Stark broadened line profile of balmer hydrogen line (H-alpha) between 1.12 × 1017 cm−3 and 1.61 × 1017 cm−3. The emission lines used in CF-LIBS were characterized for the effect due to phenomenon of self-absorption but were found insignificant. Furthermore, the concentrations determined using CF-LIBS were compared to the abundance of identical (duplicate) dry milk powder samples obtained using a standard analytical tool like inductively coupled plasma-optical emission spectroscopy. Both the results were in outstanding harmony. Our study showed that LIBS is a powerful and rapid approach to quantify the chemical concentrations of food products.

Plasma diagnostics by optical emission spectroscopy on manganese ore in conjunction with XRD, XRF and SEM-EDS

Manganese (Mn) is an important industrial mineral. Information about the chemical and phase constitution along with the concentration of impurities presented in Mn ore is compulsory in assessing its suitability for different applications. We performed the qualitative and quantitative analysis of low-grade Mn ore (LGMO) using laser-induced breakdown spectroscopy (LIBS) in conjunction with x-ray diffraction (XRD), x-ray fluorescence (XRF) and scanning electron microscopy (SEM) coupled with energy dispersive x-ray electron spectroscopy (EDS). The optical emission spectra of the LGMO sample displayed the presence of Mn, Si, Ca, Fe, Al, Mg, V, Ti, Sr, Ni, Na, Ba and Li. The plasma parameters, electron temperature and number density were estimated using the Boltzmann plot and Stark broadening line profile methods and were found to be 7500 K ± 750 K and 8.18 ± 0.8 × 1017 cm−3, respectively. Quantitative analysis was performed using the calibration-free LIBS (CF-LIBS) method and its outcome along with XRD, XRF and SEM-EDS data showed almost analogous elemental composition, while the LIBS method gave acceptably precise elemental analysis by detecting the low atomic number element Li besides V and Sr. The results obtained using LIBS for the LGMO exhibited its ability as a powerful analytical tool and XRF, XRD and SEM-EDS as complementary methods for the compositional analysis of complex low-grade mineral ore.

Quantitative analysis of Fuller's earth using laser-induced breakdown spectroscopy and inductively coupled plasma/optical emission spectroscopy.

Fuller's earth, most commonly known as Multani Matti (clay) in Urdu, among its various utilizations is traditionally used in skin care cosmetics, particularly for removing blackheads and to treat oily skin. It is also used for improving skin complexion. In this paper, laser-induced breakdown spectroscopy (LIBS) was effectively employed for the quantitative investigation of various clay samples for their special uses. To get the LIBS spectra with an optimal signal-to-noise as well as for a more robust and accurate analytical investigation, different experimental parameters (laser energy, gate delay time, and the distance between target and focusing lens) were optimized before the experiments on actual samples. The analysis of emission spectra revealed the presence of many different elements, including Al, Ca, Fe, Mg, Mn, Na, K, Li, S, Si, and Zn. The electron number density and plasma temperatures were determined using the Stark broadened line profile and Boltzmann plot method, respectively. To determine the relative concentration of observed elements, we used an integrated intensity ratio method, integrated intensity of every line from all elements, and calibration free (CF)-LIBS. The prevailing condition of local thermodynamic equilibrium during the experimental executions was verified with multiple criteria. The spectral lines used in CF-LIBS were characterized for the influence from the self-absorption phenomenon, but the same was found insignificant. The findings of our LIBS system were found to agree excellently with the outcomes of the inductively coupled plasma/optical emission spectroscopy, thereby yielding a high statistical correlation factor and hence enlighten the significance of LIBS as a safe and reliable tool for elemental analysis of clay samples.

Spectral analysis of mint (pudina) using laser-induced breakdown spectroscopy and inductively coupled plasma/atomic emission spectroscopy

In the current study, pulsed Nd:YAG laser-induced breakdown spectroscopy (LIBS) was successfully applied, at 532 nm with a suitable detector, for the spectral analysis of mint (domestic mint and wild mint) available in Pakistan. From the spectral emissions of the mint plasmas recorded with the spectrometer (LIBS2000+, Ocean Optics, Inc.), 17 elements were identified in the domestic mint whereas the wild mint was observed to have 18 different elements, comprising both nutritional elements and toxic metals. Prior to recording the spectral emissions, the sensitivity of our LIBS detection was enhanced by optimizing various LIBS parameters. Under ambient environments, a laser pulse irradiance of about 2.0 × 1011 W cm−2 was employed for the generation of the plasmas on the surfaces of the target samples. The quantitative analyses were performed via calibration curves drawn for all the elements through standard samples prepared in a known concentration in the mint matrix, as well as by a weight percentage method under the assumptions of local thermodynamic equilibrium and optically thin plasma. The electron temperature and number density were determined through the Boltzmann plot method and stark broadened line profile method, respectively, using Ca-I spectral lines. Furthermore, to verify the precision of our LIBS findings, the abundance of each element in the mint samples was also estimated by means of a standard analytical tool, such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES). The outcomes of the LIBS system were found to be in good agreement with the results of ICP/AES statistically, which guarantees that the method is reliable in the illustration and detection of both nutritional and toxic chemical differences in the mint samples, and is hence a step forward in securing human health through environmental and agricultural development.

Spatially resolved LAAS/OES diagnostics of a free-burning Ar arc: measurements of excited atom densities

Spatially resolved optical diagnostics are applied to a free-burning DC arc in argon at atmospheric pressure. Densities of metastable and resonance -atoms are measured by laser atomic absorption spectroscopy (LAAS). The novel LAAS design allowed for an extended range of wavelength scan covering the complete Stark broadened line profile (∼ nm). High spatial resolution of 0.2 mm allowed measurements of atom densities and line profiles in the regions of high-temperature gradients. Besides absorbing -states, the radiating -states were measured using optical emission spectroscopy (OES). Results of the LAAS and OES measurements are compared with the nonequilibrium collisional-radiative model. Measurement of metastable states in the non-radiating regions near the cathode reveals the existence of a ‘collar’ effect. The interpretation of the effect with a focus on transport of resonance radiation is given, quantitative agreement between simulations and experiment is reached.

Spectroscopic investigations of the laser induced thallium plasma

Laser-induced breakdown spectroscopy has been used for the spectroscopic characterization of thallium (Tl) plasma, produced using the fundamental harmonic of a Q-switched Nd:YAG laser. The optical emission was recorded in the spectral range of 200–720 nm using a set of five miniature spectrometers with 2.5 μs delay time and 2.1 ms gate width. The plasma temperature was determined using the Boltzmann-plot method, and the electron number density was deduced from the Stark broadened line profile of Tl (I) 322.97 nm line. The plasma temperature and electron number density have been evaluated as a function of laser irradiance (5.2 × 1010 to 8.2 × 1010 W cm−2) which increases from 11 450–13 780 K and (5.2–6.2) × 1017 cm−3 respectively. The spatial profile of these parameters shows a decreasing trend from 13 000–7600 K and (6.3–5.8) × 1017 cm−3 along the plume expansion length up to 2.5 mm from the target surface. The spatial behavior of the plasma parameters has been discussed in relation to the reported temporal trend to indicate inter-relation of the spatio-temporal profile of the laser induced plasma.

Tungsten ion source under double-pulse laser ablation system

New tungsten ion source is produced by using single and double-pulse laser ablation system. Combined collinear Nd:YAG laser beams (266+1064 nm) are optimized to focus on the sample in air. Optimization of the experimental parameters is achieved to enhance the signal-to-noise ratio of the emission spectra. The velocity distribution of the emitted plasma cloud is carefully measured. The influences of the potential difference between the bias electrodes, laser wavelength and intensity on the current signal are also studied. The results show that the increase in the tungsten ion velocity under the double-pulse lasers causes the output current signal to increase by about three folds. The electron density and temperature are calculated by using the Stark-broadened line profile of tungsten line and Boltzmann plot method of the upper energy levels, respectively. The signal intensity dependence of the tungsten ion angular distribution is also analyzed. The results indicate that the double-pulse laser ablation configuration is more potent technique for producing more metal ion source deposition, thin film formation, and activated plasma-facing component material.

Characterization of laser produced plasma using laser induced breakdown spectroscopy

The plasma parameter studies of the Nd:YAG (neodymium-doped yttrium aluminum garnet, Nd:Y3Al15O12) crystal by using the fundamental (1064 nm) and second (532 nm) harmonics of Nd:YAG laser are reported. The electron temperature (T e ) and electron number density (N e) were determined using the Boltzmann plot method and the Stark-broadened line profile, respectively. An increase in the plasma parameters have been observed with an increase in the laser irradiance for both laser modes. The electron temperatures were calculated in the range of 0.53–0.66 eV for 1064 nm and 0.47–0.60 eV for 532 nm, and the electron number densities were determined in the range of 7.43 × 1015–3.27 × 1016 cm−3 for 1064 nm and 1.35 × 1016–3.97 × 1016 cm−3 for 532 nm in the studied irradiance range of 1.19–12.5 GW/cm2. However, the spatial evolution of the plasma parameters investigated up to 2.75 mm away from the target surface at a fixed laser irradiance of 6.51 GW/cm2 showed a decreasing trend. In addition, the estimated values of the inverse bremsstrahlung (IB) absorption coefficients at both laser wavelengths showed that the IB process is dominant for the 1064-nm laser.