Line Intensity Ratios Research Articles

2D-resolved electric field development in helium coplanar DBD: spectrally filtered ICCD camera approach

Electric field strength in diffuse coplanar barrier discharge in helium at atmospheric pressure, driven by AC voltage (amplitude 1.5 kV, frequency 10 kHz), was measured by optical emission spectroscopy. Two helium singlet lines at 667.8 nm (He I 2 1P–3 1D) and 728.1 nm (He I 2 1P–3 1S) were recorded within the discharge space and period with a high spatial (20 μm) and temporal (50 ns) resolution and analyzed with the line intensity ratio method developed by Ivković et al 2014. A novel experimental approach, based on a direct observation of the discharge by ICCD camera through two interference filters, was developed to obtain 2D spatially resolved distributions of the electric field. The obtained results proved the existence of several developing regions of high electric field, namely the cathode-directed and anode ionization waves. The electric field in the cathode-directed wave peaked at 32 kV/cm during the first contact of the wave with the cathode’s dielectrics, followed by a decrease to values of 15–25 kV/cm above the electrode. The electric field in the anode-directed wave was lower, reading some 15 kV/cm. The performed ‘sensitivity analysis’ pointed out the crucial importance of precise temporal and spatial synchronization for the techniques based on the intensity ratio of two spectral lines. Artificially introduced 50 ns misalignment between the measured data of both spectral lines resulted in the substantial distortion of the electric field map. Reduction of the temporal resolution from 50 to 100 ns led to the decrease of electric field maxima by 30%. The reduction of the spatial resolution from 20 to 40 μm decreased the maximal field value by 10%.

Laser-Induced Breakdown Spectroscopy Coupled with PCA Study of Human Tooth

The present study focuses on the laser-induced breakdown spectroscopy (LIBS) studies on different parts of tooth samples. The hardness of different parts of tooth samples belonging to different age groups has been studied using ionic-to-atomic intensity ratio of Ca spectral line. From this ratio, we infer that enamel is the hardest part of teeth. The principal component analysis (PCA) on LIBS data of different parts of teeth gives PC1 (96%) and PC2 (4%), which explains maximum variance present in data set. Therefore, this work demonstrates the suitability of LIBS along with PCA for routine in vitro/in vivo dental practices.

РЕНТГЕНОЛЮМИНЕСЦЕНТНЫЕ КОМПОЗИТЫ НА ОСНОВЕ ПОЛИКРИСТАЛЛИЧЕСКОГО АЛМАЗА С ИНТЕГРИРОВАННЫМИ НАНОЧАСТИЦАМИ NaGdF4:Eu ДЛЯ ФОТОНИКИ

Разработаны люминесцентные алмазные композиты c интегрированными наночастицами β-NaGdF4:Eu, обладающие высокоинтенсивной узкополосной рентгенолюминесценцией на длине волны 612 нм. Отмечена концентрационная зависимость интенсивности рентгенолюминесценции от содержания частиц. Использование нанопорошков β-NaGdF4:Eu позволило получить интенсивную рентгенолюминесценцию с более высоким соотношением сигнал/шум, нежели было достигнуто ранее.
 
 Работа выполнена при финансовой поддержке гранта РФФИ № 16-29-11784-офи.
 Результаты получены с использованием оборудования центров коллективного пользования ИОФ РАН и ИОНХ РАН.

Forbidden component of the Be II 436.1 nm line recorded from pulsed gas discharge plasma

We report results of the experimental study of the singly charged beryllium spectral line 436.1 nm, transition , and forbidden component, transition , which is for the first time identified in this work. Beryllium lines are recorded from gas discharge, after ablation of a beryllium oxide discharge tube, running in pulsed regime with the following gases: helium with traces of hydrogen, argon with traces of hydrogen and pure krypton. The ratio of line intensities and wavelength separation of the Be II 436.1 nm line and neighbouring line located at the blue wing are followed in the electron density range (1.16–6.4) × 1022 m−3 determined from the hydrogen Balmer beta line () in the electron temperature interval between 10500 K and 15500 K. The functional dependence of the wavelength separation range and peak intensity ratio of these lines upon electron number density suggests the complex profile of the forbidden and allowed line, which can be used for diagnostics of low-temperature beryllium containing plasmas.

Mode Transition in an Inductively Coupled Argon–Mercury Mixture Discharge Studied by Interferometer and Optical Emission Spectroscopy

The E–H-mode-transition process in an inductively coupled argon–mercury mixture discharge plasma was investigated by an interferometer and a spectrometer. The transition powers upon different natural pressures and mercury content were studied. The electron density versus input power under several discharge conditions in the E mode and H mode was measured detailedly by the interferometer. These results suggested that the nonlinear effects of power absorption and dissipation play a significant role in the mode transition process. In addition, the optical emission system was employed to obtain the intensity ratios of spectral lines at different mercury proportions, which shed light on the mechanism of stepwise ionization and the variability of H-to-E-mode-transition powers in the argon–mercury mixture discharge.

High-Power X-Ray Line Radiation of the Plasma Produced in a Collision of High-Energy Plasma Flows

Results are presented from experimental studies of a pulsed source of soft X-ray (SXR) emission with photon energies in the range of 0.4–1 keV and an output energy of 2–10 kJ. SXR pulses with a duration of 10–15 μs were generated in collisions of two plasma flows propagating toward one another in a longitudinal magnetic field. The plasma flows with velocities of (2–4) × 107 cm/s and energy contents of 70–100 kJ were produced by two electrodynamic coaxial accelerators with pulsed gas injection. Nitrogen and neon, as well as their mixtures with deuterium, were used as working gases. The diagnostic equipment is described, and the experimental results obtained under different operating conditions are discussed. In particular, X-ray spectroscopy was used to study the high-temperature plasma produced in a collision of two plasma flows. The observed intensities of spectral lines are compared with the results of detailed kinetic calculations performed in a steady-state approximation. The calculations of the nitrogen and neon kinetics have shown that the electron temperature of a nitrogen plasma can be most conveniently determined from the intensity ratio of the resonance lines of He- and H-like nitrogen ions, while that of a neon plasma, from the intensity ratio between the resonance line of He-like Ne IX ions and the 3p−2s line of Li-like Ne VIII ions. In the experiments with plasma flows containing nitrogen ions, the electron temperature was found to be ≈120 eV, whereas in the experiments with plasma flows containing neon ions, it was 160–170 eV.

High-J CO emission spatial distribution and excitation in the Orion Bar

Context. With Herschel, we can for the first time observe a wealth of high-J CO lines in the interstellar medium with a high angular resolution. These lines are specifically useful for tracing the warm and dense gas and are therefore very appropriate for a study of strongly irradiated dense photodissocation regions (PDRs). Aims. We characterize the morphology of CO J = 19–18 emission and study the high-J CO excitation in a highly UV-irradiated prototypical PDR, the Orion Bar. Methods. We used fully sampled maps of CO J = 19–18 emission with the Photoconductor Array Camera and Spectrometer (PACS) on board the Herschel Space Observatory over an area of ~110′′ × 110′′ with an angular resolution of 9′′. We studied the morphology of this high-J CO line in the Orion Bar and in the region in front and behind the Bar, and compared it with lower-J lines of CO from J = 5–4 to J = 13–12 and 13CO from J = 5–4 to J = 11–10 emission observed with the Herschel Spectral and Photometric Imaging Receiver (SPIRE). In addition, we compared the high-J CO to polycyclic aromatic hydrocarbon (PAH) emission and vibrationally excited H2. We used the CO and 13CO observations and the RADEX model to derive the physical conditions in the warm molecular gas layers. Results. The CO J = 19–18 line is detected unambiguously everywhere in the observed region, in the Bar, and in front and behind of it. In the Bar, the most striking features are several knots of enhanced emission that probably result from column and/or volume density enhancements. The corresponding structures are most likely even smaller than what PACS is able to resolve. The high-J CO line mostly arises from the warm edge of the Orion Bar PDR, while the lower-J lines arise from a colder region farther inside the molecular cloud. Even if it is slightly shifted farther into the PDR, the high-J CO emission peaks are very close to the H/H2 dissociation front, as traced by the peaks of H2 vibrational emission. Our results also suggest that the high-J CO emitting gas is mainly excited by photoelectric heating. The CO J = 19–18/J = 12–11 line intensity ratio peaks in front of the CO J = 19–18 emission between the dissociation and ionization fronts, where the PAH emission also peak. A warm or hot molecular gas could thus be present in the atomic region where the intense UV radiation is mostly unshielded. In agreement with recent ALMA detections, low column densities of hot molecular gas seem to exist between the ionization and dissociation fronts. As found in other studies, the best fit with RADEX modeling for beam-averaged physical conditions is for a density of 106 cm−3 and a high thermal pressure (P∕k = nH × T) of ~1–2 × 108 K cm−3. Conclusions. The high-J CO emission is concentrated close to the dissociation front in the Orion Bar. Hot CO may also lie in the atomic PDR between the ionization and dissociation fronts, which is consistent with the dynamical and photoevaporation effects.

Real-time identification of plastics by types using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy was applied for real-time identification of different types of plastics. The plasma emission spectra of polypropylene, acrylonitrile–butadiene–styrene, polystyrene, and polyethylene terephthalate, the most commonly used plastics in black household appliances, were studied. It was confirmed that the C/H spectral line intensity ratio varies depending on the type of plastics. Aliphatic and aromatic polymers were discriminated owing to the presence of delocalized C–C bonds in the aromatic fragments, revealing a correlation between the chemical structure and emission of the C2 Swan bands. Plastics containing a heteroatom could be selectively detected by monitoring the emission line characteristics of the heteroatom. Four types of plastics were successfully identified despite their similar chemical structure.

Predictions of DKIST/DL-NIRSP Observations for an Off-limb Kink-unstable Coronal Loop

Abstract Synthetic intensity maps are generated from a 3D kink-unstable flux rope simulation using several DKIST/DL-NIRSP spectral lines to make a prediction of the observational signatures of energy transport and release. The reconstructed large field-of-view intensity mosaics and single tile sit-and-stare high-cadence image sequences show detailed, fine-scale structure and exhibit signatures of wave propagation, redistribution of heat, flows, and fine-scale bursts. These fine-scale bursts are present in the synthetic Doppler velocity maps and can be interpreted as evidence for small-scale magnetic reconnection at the loop boundary. The spectral lines reveal the different thermodynamic structures of the loop, with the hotter lines showing the loop interior and braiding and the cooler lines showing the radial edges of the loop. The synthetic observations of DL-NIRSP are found to preserve the radial expansion, and hence the loop radius can be measured accurately. The electron number density can be estimated using the intensity ratio of the Fe xiii lines at 10747 and 10798 Å. The estimated density from this ratio is correct to within ±10% during the later phases of the evolution; however, it is less accurate initially when line-of-sight density inhomogeneities contribute to the Fe xiii intensity, resulting in an overprediction of the density by ≈30%. The identified signatures are all above a conservative estimate for instrument noise and therefore will be detectable. In summary, we have used forward modeling to demonstrate that the coronal off-limb mode of DKIST/DL-NIRSP will be able to detect multiple independent signatures of a kink-unstable loop and observe small-scale transient features including loop braiding/twisting and small-scale reconnection events occurring at the radial edge of the loop.

On the circumstellar envelopes of semi-regular long-period variables

AbstractThe mass loss process along the AGB phase is crucial for the formation of circumstellar envelopes (CSEs), which in the post-AGB phase will evolve into planetary nebulae (PNe). There are still important issues that need to be further explored in this field; in particular, the formation of axially symmetric PNe from spherical CSEs. To address the problem, we have conducted high S/N IRAM 30 m observations of 12COJ = 1−0 and J = 2−1, and 13COJ = 1−0 in a volume-limited unbiased sample of semi-regular variables (SRs). We also conducted Yebes 40 m SiO J = 1−0 observations in 1/2 of the sample in order to complement our 12CO observations. We report a moderate correlation between mass loss rate and the 12CO(1−0)−to−12CO(2−1) line intensity ratio, introducing a possible new method for determining mass loss rates of SRs with short analysis time. We also find that for several stars the SiO profiles are very similar to the 12CO profiles, a totally unexpected result unless these are non-standard envelopes.

Mapping the emission line strengths and kinematics of supernova remnant S147 with extensive LAMOST spectroscopic observations

We present extensive spectroscopic observations of supernova remnant (SNR) S147 collected with the Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST). The spectra were carefully sky-subtracted taking into account the complex filamentary structure of S147. We have utilized all available LAMOST spectra toward S147, including sky and stellar spectra. By measuring the prominent optical emission lines including Hα, [N ii] λλ 6548 and 6584 and [S ii] λλ 6717, 6731, we present maps of radial velocity and line intensity ratio covering the whole nebula of S147 with unprecedented detail. The maps spatially correlate well with the complex filamentary structure of S147. For the central 2° of S147, the radial velocity varies from −100 to 100 km s−1 and has peaks between ∼ 0 and 10 km s−1. The intensity ratios of Hα/[S ii] λλ 6717, 6731, [S ii] λ 6717/λ 6731 and Hα/[N ii] λ 6584 peak at about 0.77, 1.35 and 1.48, respectively, with a scatter of 0.17, 0.19 and 0.37, respectively. The intensity ratios are consistent with the literature values. However, the range of variations of line intensity ratios estimated here, which are representative of the whole nebula, is larger than previously estimated.

Simulating a low-temperature Maxwellian plasma using SH-HtscEBIT

This paper reports an experimental realization of a low-temperature quasi-Maxwell–Boltzmann plasma in an electron beam ion trap (EBIT) by employing a special energy sweep technique. A Maxwellian C IV plasma with electron temperatures in the range 10–40 eV is simulated in the Shanghai high-temperature superconducting EBIT (SH-HtscEBIT), which requires stable performance of the EBIT under the extreme condition of ultralow electron beam energy. The C IV spectra are obtained by an extreme ultraviolet spectrometer in the wavelength region 290–400 Å. The measured spectral line intensity ratios are compared with the results of calculations using a collisional-radiative model. The mean difference between the experimental and theoretical results in the simulated temperature region is about 14%.

Development of the Method of Calibration Equations for the X-Ray Fluorescence Analysis of Multicomponent Samples in the Presence of Undetectable Elements

New calibration equations are proposed based on the use of intensity ratios of spectral lines and peaks of coherently and incoherently scattered characteristic radiation of an X-ray tube. Prospects for their application to the X-ray fluorescence analysis of samples containing undetectable light elements are shown. The proposed method ensures high precision of determination and performance of analysis in the lack of adequate reference samples. The method was tested on an example of analysis of standard samples of bronze and samples of iron oxide materials.

Helium line emission spectroscopy in recombining detached plasmas

Line emissions from helium (He) plasmas have been used for measurement of electron density and temperature in various situations. We performed measurements of He line intensities in recombining plasmas in a divertor simulator, followed by discussion of some potential difficulties of using the line intensity ratio (LIR) method in a divertor environment under detached conditions. When using four line emissions (501.6, 667.8, 706.5, and 728.1 nm), the discrepancy of the results compared to results from the laser Thomson scattering (LTS) method increased along with increasing gas pressure. However, the LIR method agreed well with LTS when a recombination sensitive line emission (447.1 nm) was added. The influence of the transport of metastable atoms is also discussed. Additionally, anomalous characteristics of the LIR method were revealed in hydrogen helium mixture plasmas when the temperature was in the range of 1–4 eV. These anomalies were likely attributable to the dissociative recombination of HeH+.

Luminescence thermometry using Gd2Zr2O7:Eu3+

In this paper we study the possibility of using the synthesized nanopowder samples of Gd2Zr2O7:Eu3+ for temperature measurements by analyzing the temperature effects on its photoluminescence. The nanopowder was prepared by solution combustion synthesis method. The photoluminescence spectra used for analysis of Gd2Zr2O7:Eu3+ nano phosphor optical emission temperature dependence were acquired using continuous laser diode excitation at 405 nm. The temperature dependencies of line emission intensities of transitions from 5D0 and 5D1 energy levels to the ground state were analyzed. Based on this analysis we use the two lines intensity ratio method for temperature sensing. Our results show that the synthesized material can be efficiently used as thermographic phosphor up to 650 K.

Application of He I Line Intensity Ratio Method to Tokamak Plasma in TOKASTAR-2

Application of He I Line Intensity Ratio Method to Tokamak Plasma in TOKASTAR-2

Optimization of simultaneous determination of metals in commercial pumpkin seed oils using inductively coupled atomic emission spectrometry

In this work, the inductively coupled plasma atomic emission spectrometry (ICP-AES) was developed and validated for determination of 27 metals in nine pumpkin oils from two production processes (cold pressed and roasted). A microwave assisted digestion was applied for the dissolution of the samples. To evaluate plasma robustness and analytical performance, the Mg II 280.270 nm/Mg I 285.213 nm (Mg II/Mg I) line intensity ratio was used. The robust plasma conditions in axial/radial view mode were reached at an RW power of 1150 W and an argon nebulizer flow rate of 0.5 L/min. The method is evaluated by application of the standard addition method and by recovery test. In general, the recoveries for all elements in pumpkin seed oils were between 90% and 110% except, only for Cd, Pb and As they were <90% and >110%. The most abundant element is K followed by, Mg, P, Ca and Na. Pumpkin seed oils were also found to be a good source of Fe, Zn, Cu and Mn. The highest levels of analyzed elements were found in pumpkin seed oils producing from the roasted pumpkin seed paste. In all samples, the content of heavy metals was below the recommended tolerable levels proposed by Joint FAO/WHO Expert Committee on Food Additives and does not a pose a health risk for the consumer. The levels of the metals in pumpkin seed oils were also compared with those reported by the literature. Cluster analysis (CA) of the analytical data confirmed the observed differences between oils from two production processes.

Formation and migration of dislocations produced by plastic deformation in 1070 Al-alloy

Positron Annihilation Lifetime (PAL) and X-ray are common nondestructive techniques used heavily in materials science to detect deformation and thermal effects in metals and alloys. In this work, the investigated wrought 1070 Al-alloy samples were plastically deformed at room temperature using a hydraulic press. X-ray diffraction patterns of the bulk and the deformed 1070 Al-alloy, at different degrees of deformation, have been studied and analyzed using MAUD program. The lattice parameter, the grain size and the intensity ratio of the maximum diffraction lines in addition to micro-strain as a function of the degree of deformation have been determined. The 20 % deformed sample was annealed and the behavior of the positron annihilation mean lifetime of the sample was studied as a function of the annealing temperature.

Helium atom line-intensity ratios as an integrated diagnostic tool for low-pressure and low-density plasmas

The intensity ratios between specific pairs of helium atom (HeI) emission lines are functions of the electron temperature (Te) and density (ne), and these functions have been used for the analysis of Te and ne in various types of discharge plasma. We applied this method to a low-density (ne &amp;lt; 1018 m−3) plasma, where the procedure of the analysis is markedly different from that of higher-density plasmas. The 21S and 23S metastable atom densities are affected by transport, making it practically necessary to set Te, ne, the metastable atom densities, and the optical escape factors, which represent the effect of photoexcitation, as unknown variables and determine them simultaneously. Conversely, the transport of metastable atoms can be evaluated from the analysis.

Composition monitoring using plasma diagnostics during direct metal deposition (DMD) process

The monitoring and controlling of the composition during laser additive manufacturing processes have attracted considerable attention since uniform composition is essential to maintain superior material properties of the fabricated part. In this study, the composition monitoring using plasma diagnostics is successfully carried out during direct metal deposition (DMD) process. Optical emission spectroscopy (OES) is employed to observe the Ni-base superalloy plasma generated during the DMD process. Composition prediction by line intensity ratios and plasma temperature is compared, and their monitoring performance is discussed.Ni-I/Cr-I line ratios almost linearly increase with increasing Ni composition. However, the plasma temperature decreases with the Ni composition. It is also observed that bright and high temperature plasma is produced at relatively high Cr concentration (i.e., low Ni concentration) because of the low boiling point and preferential oxidation of the Cr.The regression line of the line ratio data shows the better prediction of the Ni composition than that of the plasma temperature data. It is suggested that using the plasma temperature as a monitoring tool may not be suitable due to the non-linear characteristics and low sensitivity shown in the plasma temperature data. The regression line of the Ni-I (352.45 nm)/Cr-I (399.11 nm) line ratio gives the most accurate prediction compared with the regression lines for other combinations of Ni-I and Cr-I lines. The predicted Ni composition error by the Ni-I (352.45 nm)/Cr-I (399.11 nm) line ratio ranges from 0.02% to 4.5% (average 1.6%), which shows that using the line ratio for monitoring of the composition is quite reasonable. The method to predict Ni composition is also validated through the DMD experiment using as-received Inconel 718 powder with a certified Ni concentration of 50.9% (in atomic percentage). Average prediction for the Ni composition is 51.8% (error 1.6%) when the Ni-I (352.45 nm)/Cr-I (399.11 nm) line ratio is used.