Ionic Lines Research Articles

Relativistic calculation of spectral line broadening by electron collisions in plasmas: Case of hydrogenic ions

In the present work, we compute the amplitude of the real part of the impact collision operator for the electron broadening of hydrogenic ion lines in plasmas, taking into account relativistic effects in the dynamics of the perturbing electron. Specifically, two relativistic effects are included: the modification of the cross section Mott instead of the Rutherford cross section and the modification of the velocity distribution (Maxwell–Juttner). The results are compared to the non-relativistic case.

Incoherent scatter radar observation of high frequency enhanced ion and plasma lines by X / O mode pump around critical altitude

During an experiment involving the alternating O / X mode pump, the Incoherent Scatter Radar (ISR) observation demonstrated that the high frequency enhanced ion line (HFIL) and plasma line (HFPL) did not immediately appear, but were delayed by a few seconds after the pump onset. By examining the initial behaviors of the ion line, plasma line and electron temperature as well as ionosphere condition, it is shown that (1) the HFIL and HFPL are delayed not only in the X mode pump but also in the O mode pump; (2) the HFIL can not be observed until the electron temperature is enhanced. The analysis suggests that (1) the leakage of the X mode to the O mode pump may not be ignored; (2) the spatiotemporal uncertainty, the spatiotemporal change in the profiles of ion mass and electron density, may play an important role in the lack of the Bragg condition; (3) nevertheless, the absence of parametric decay instability can not be ruled out due to the lack of matching condition caused by the spatiotemporal uncertainty.

Rare earth concentration dependence on the glass optical properties in the system CaO[sbnd]GeO2[sbnd]Li2O[sbnd]B2O3 (RE = Dy3+)

Dy3+ doped glasses from the oxide system CaOGeO2Li2OB2O3 with different compositions were prepared by melt quenching technique. The obtained glass samples were characterized by X-ray diffraction (XRD), Differential thermal analyses (DTA), Infrared spectroscopy (IR) and Photoluminescence (PL) measurements. The X-ray analysis reveals amorphous nature of the samples. Thermal stability of the doped glasses depends more on the glass composition than the dopant concentration. IR analyses confirm some changes in the local structures of the glasses after doping. The excitation and emission spectra show typical for Dy3+ ions lines with domination of yellow emission peak. CIE coordinates and yellow-to-blue ratio of the obtained glasses is with almost the same values, therefore almost the same emitted color is expected.

Оптимизация параметров компактного источника мягкого рентгеновского излучения для работы в диапазоне длин волн 2-5 nm

This paper presents a compact source of soft X-ray radiation for operation in the wavelength range of 2-5 nm with a pulse repetition frequency of more than 500 Hz. The source parameters were optimized to reduce the intensity of ablation of the discharge volume wall and obtain the maximum intensity of the spectral lines of multicharged ions C V – 4 nm and Ar IX – 4.87 nm. The obtained results can be used in the development of a microscope for the tasks of cell lumen microscopy with nanometer resolution.

Line identification of extreme ultraviolet spectra of Mo V to Mo XVIII in EAST tokamak

The presence of high-<i>Z</i> impurities in magnetically confined fusion devices has different influences on the confinement property of the plasma due to the high cooling rate of high-<i>Z</i> impurities. The first wall of EAST is equipped with molybdenum tiles, molybdenum particles sputtered from inevitable plasma-wall interaction enter into the plasma and become high-<i>Z</i> impurity. In this paper, four fast-time-response extreme ultraviolet (EUV) spectrometers, a system which is upgraded in the EAST 2021 campaign, are used to monitor the line emission from impurity ions in the 5–500 Å wavelength range simultaneously. The in-situ wavelength calibration is carried out accurately using several well-known emission lines of low- and medium-Z impurity ions. The observed spectral lines are carefully identified based on the National Institute of Standards Technology (NIST) database, previously published experimental data and the time evolution of the normalized line intensity of emission lines from impurity ions. At the lower electron temperature (<i>T</i><sub>e0</sub> = 1.5 keV), the EUV spectra emitted from molybdenum ions in the range of 5–485 Å are systematically identified in EAST discharges accompanied with spontaneous sputtering events. As a result, two unresolved transition arrays of molybdenum spectra composed of Mo<sup>19+</sup>-Mo<sup>24+</sup> (Mo XX-Mo XXV) and Mo<sup>16+</sup>-Mo<sup>29+</sup> (Mo XVII-Mo XXX) are observed in the ranges of 15–30 Å and 65–95 Å. In addition, several spectral lines of lower molybdenum ions of Mo<sup>4+</sup>-Mo<sup>17+</sup> (Mo V-Mo XVIII) in the ranges of 27–60 Å and 120–485 Å are observed and identified on EAST for the first time, including a few strong and isolated forbidden and resonant lines, e.g. Mo XII at 329.414 Å, 336.639 Å and 381.125 Å, Mo XIII at 340.909 Å and 352.994 Å, Mo XIV at 373.647 Å and 423.576 Å, Mo XV at 50.448 Å, 57.927 Å and 58.832 Å. Six spectral lines are newly observed in the range of 27–32 Å, i.e. (27.21 ± 0.01) Å, (27.37 ± 0.01) Å, (28.99 ± 0.01) Å, (30.81 ± 0.01) Å, (31.54 ± 0.01) Å and (31.83 ± 0.01) Å, which may be Mo XV-Mo XVIII spectral lines. As a result, twelve strong and isolated spectral lines are chosen in routine observation for impurity transport physical study. The identification of these spectral lines not only enriches the molybdenum atom database, but also provides a solid experimental data base for magnetically confined devices to study the behavior and transport in core and edge plasmas of high-Z impurity.

Optimization of parameters of a compact soft X-ray source for operation in the wavelength range 2-5 nm

This paper presents a compact source of soft X-ray radiation for operation in the wavelength range of 2-5 nm with a pulse repetition frequency of more than 500 Hz. The source parameters were optimized to reduce the intensity of ablation of the discharge volume wall and obtain the maximum intensity of the spectral lines of multicharged ions C V --- 4 nm and Ar IX --- 4.87 nm. The obtained results can be used in the development of a microscope for the tasks of cell transmission microscopy with nanometer resolution. Keywords: High-voltage pulse generator, Capillary plasma, "Water-window" microscopy.

Collisional-radiative recombination of Ne-=SUP=-++-=/SUP=- and Ne-=SUP=-+-=/SUP=- ions with electrons in the decaying plasma of a low-pressure barrier discharge

The results of an experimental study and simulation of radiation generated by the processes of collisional-radiative recombination of neon ions Ne+ and Ne++ with electrons of the decaying plasma are presented. Plasma was created by a barrier discharge in a cylindrical glass tube with electrodes on its surface. Experimental conditions: neon pressure 0.65 Torr, electron density at the initial stage of the afterglow [e] ~ (1-5)·1011 cm-3. The main attention is paid to the comparative analysis of the collisional-radiative recombination of Ne+ and Ne++ ions based on the numerical solution of coupled differential equations for the densities of charged and long-lived excited particles and the electron temperature, taking into account the main elementary processes in decaying neon plasma. Comparison of the model solutions with the intensities of ionic and atomic spectral lines measured by the multichannel photon counting method indicates the need to refine the dependence of the rate of collisional-radiative recombination on the ion charge. Keywords: dielectric barrier discharge, doubly charged ions, collisional-radiative recombination, decaying plasma, elementary processes.

Ударно-радиационная рекомбинация ионов Ne-=SUP=-++-=/SUP=- и Ne-=SUP=-+-=/SUP=- c электронами в распадающейся плазме барьерного разряда низкого давления

The results of an experimental study and simulation of radiation generated by the processes of collisional-radiative recombination of neon ions Ne+ and Ne++ with electrons of the decaying plasma are presented. Plasma was created by a barrier discharge in a cylindrical glass tube with electrodes on its surface. Experimental conditions: neon pressure 0.65 Torr, electron density at the initial stage of the afterglow [e] ≈ (1 - 5) • 1011 cm-3. The main attention is paid to the comparative analysis of the collisional-radiative recombination of Ne+ and Ne++ ions based on the numerical solution of coupled differential equations for the densities of charged and long-lived excited particles and the electron temperature, taking into account the main elementary processes in decaying neon plasma. Comparison of the model solutions with the intensities of ionic and atomic spectral lines measured by the multichannel photon counting method indicates the need to refine the dependence of the rate of collisional-radiative recombination on the ion charge.

High spectral stability and quantitative accuracy of LIBS by optimization of a combined atomic and ionic line algorithm

We proposed an improved algorithm based on the optimization of a combined atomic and ionic line algorithm for LIBS analysis.

Emission spectra of molecular gases CHF-=SUB=-3-=/SUB=-, CCl-=SUB=-2-=/SUB=-F-=SUB=-2-=/SUB=-, SF-=SUB=-6-=/SUB=- in the range 3-20 nm under pulsed laser excitation using various gas jets as targets

The article considers the results of studies of the emission spectra of CHF3, CCl2F2, SF6 upon excitation by pulsed laser radiation. We used Nd : YAG laser, λ = 1064 nm, tau = 5 ns, and Epulse = 0.8 J. The spectral range of 3-20 nm was studied. We used capillary and supersonic conical nozzles with dcrit = 145 μm, 2α = 12o, L = 5 mm, and dcrit = 450 μm, 2α = 11o, L = 5 mm to form an atomic cluster beam. The emission spectra for various gas targets were obtained, the obtained spectra were deciphered, and the ions emitting in this spectral range were determined. We observed that with increasing particle concentration in the zone of laser spark, the radiation intensity increases. In this case, the intensity of ion lines with high degrees of ionization increases faster. Keywords: cluster beams, extreme ultraviolet radiation, emission spectra, laser spark, x-ray spectrometer-monochromator.

Эмиссионные спектры молекулярных газов CHF-=SUB=-3-=/SUB=-, CCl-=SUB=-2-=/SUB=-F-=SUB=-2-=/SUB=-, SF-=SUB=-6-=/SUB=- в диапазоне 3-20 nm при импульсном лазерном возбуждении с использованием различных газовых струй в качестве мишеней

The article considers the results of studies of the emission spectra of CHF3, CCl2F2, SF6 upon excitation by pulsed laser radiation. We used Nd:YAG laser, λ = 1064 nm, τ = 5 ns, and Epulse = 0.8 J. The spectral range of 3-20 nm was studied. We used capillary and supersonic conical nozzles with dcrit = 145 μm, 2α = 12o, L = 5 mm, and dcrit = 450 μm, 2α = 11o, L = 5 mm to form an atomic cluster beam. The emission spectra for various gas targets were obtained, the obtained spectra were deciphered, and the ions emitting in this spectral range were determined. We observed that with increasing particle concentration in the zone of laser spark, the radiation intensity increases. In this case, the intensity of ion lines with high degrees of ionization increases faster.

Online detection and source tracing of VOCs in the air

Atmospheric volatile organic compounds (VOCs) are one of the major air pollutants. In this work, a novel online detection and source tracing method for VOCs in the air was developed based on laser-induced breakdown spectroscopy (LIBS) and machine learning (ML). Five haloalkanes were taken as examples, and in the plasma emission spectra of them, atomic or ionic lines of halogens were clearly observed. The spectra of different VOCs were analyzed via principal component analysis (PCA). Furthermore, a classification model was established based on BP neural network and achieved a recognition accuracy of 99.77%, indicating that this method has great potential for identifying air contaminant of VOCs, as well as distinguishing some VOCs molecules.

Data fusion of LIBS and PIL hyperspectral imaging: Understanding the luminescence phenomenon of a complex mineral sample

Laser-induced breakdown spectroscopy (LIBS) imaging is an innovative technique that associates the valuable atomic, ionic and molecular emission signals of the parent spectroscopy with spatial information. LIBS works using a powerful pulse laser as excitation source, to generate a plasma exhibiting emission lines of atoms, ions and molecules present in the ablated matter. The advantages of LIBS imaging are potential high sensitivity (in the order of ppm), easy sample preparation, fast acquisition rate (up to 1 kHz) and μm scale spatial resolution (weight of the ablated material in the order of ng). Despite these positive aspects, LIBS imaging easily provides datasets consisting of several million spectra, each containing several thousand spectral channels. Under these conditions, the current chemometric analyses of the raw data are still possible, but require too high computing resources. Therefore, the aim of this work is to propose a data compression strategy oriented to keep the most relevant spectral channel and pixel information to facilitate, fast and reliable signal unmixing for an exhaustive exploration of complex samples. This strategy will apply not only to the context of LIBS image analysis, but to the fusion of LIBS with other imaging technologies, a scenario where the data compression step becomes even more mandatory. The data fusion strategy will be applied to the analysis of a heterogeneous kyanite mineral sample containing several trace elements by LIBS imaging associated with plasma induced luminescence (PIL) imaging, these two signals being acquired simultaneously by the same microscope. The association of compression and spectral data fusion will allow extracting the compounds in the mineral sample associated with a fused LIBS/PIL fingerprint. This LIBS/PIL association will be essential to interpret the PIL spectral information, which is nowadays very complex due to the natural overlapped signals provided by this technique.

Improving Calibration Strategy for LIBS Heavy Metals Analysis in Agriculture Applications

A new calibration procedure, known as mapping conditional-calibration laser-induced breakdown spectroscopy (LIBS), has been suggested to improve analysis results for heterogeneous samples. The procedure is based on LIBS elemental mapping, followed by signal conditioning in every sampling spot to skip signal outliers, then by finalizing the calibration curve construction. The suggested mapping conditional calibration procedure was verified for zinc analysis in soybean grist samples. The laser parameters correspond to those of the hand-held LIBS instrument in order to estimate the influence of sample surface heterogeneity under on-site analysis conditions. The laser spot (60 μm) was equal to or smaller than the typical size of grist particles (40–500 μm) but laser crater dimensions were significantly greater and varied widely (150–450 μm). The LIBS mapping of different spectral signals (atomic and ionic lines for major and minor components) was achieved. Elemental maps were normalized to achieve signal maps that were conditionally spotted to skip signal outliers. It was demonstrated that the suggested mapping conditional-calibration LIBS provided 15 ppm RMSECV for zinc determination in heterogeneous samples, which is typical for agricultural products.

Influence of Gas Type on the Laser Produced Graphite Plasma

Plasma graphite creation by a pulsed Nd: YAG laser with a wavelength of 1064nm to a target in vacuum in two cases (Argon, Air) with varied gas pressures and the resulting spectrum was diagnosed using optical emission spectroscopy for the wavelength range 320-740nm electron temperature Te and electron density ne Debye lengthλD , and plasma frequency f p were calculated. The results showed that increasing the pulse laser energy causes all plasma parameters of both gases under study to increase, as well as a rise in the emission line intensity. The ionization energy of target atoms determines the presence of an element’s atomic and ionic emission lines in the emission spectrum, increase in pressure decreases the electron temperature, and Debye length, also plasma frequency and electron density increase, as it has been proven that the type of gas does not affect the properties of plasma.

Spectroscopically Identified Emission Line Galaxy Pairs in the WISP Survey*

Abstract We identify a sample of spectroscopically measured emission line galaxy (ELG) Pairs up to z = 1.6 from the Wide Field Camera 3 (WFC3) Infrared Spectroscopic Parallels (WISP) survey. WISP obtained slitless, near-infrared grism spectroscopy along with direct imaging in the J and H bands by observing in the pure-parallel mode with the WFC3 on board the Hubble Space Telescope. From our search of 419 WISP fields covering an area of ∼0.5 deg2, we find 413 ELG pair systems, mostly H α emitters. We then derive reliable star formation rates (SFRs) based on the attenuation-corrected H α fluxes. Compared to isolated galaxies, we find an average SFR enhancement of 40%–65%, which is stronger for major Pairs and Pairs with smaller velocity separations (Δ v < 300 km s−1). Based on the stacked spectra from various subsamples, we study the trends of emission line ratios in pairs, and find a general consistency with enhanced lower ionization lines. We study the pair fraction among ELGs, and find a marginally significant increase with redshift f ∝ (1 + z) α , where the power-law index α = 0.58 ± 0.17 from z ∼ 0.2 to ∼1.6. The fraction of active galactic nuclei is found to be the same in the ELG Pairs as compared to the isolated ELGs.

Can nebular He II emission be explained by ultra-luminous X-ray sources?

Context. The shape of the ionising spectra of galaxies is a key ingredient to reveal their physical properties and for our understanding of the ionising background radiation. A long-standing unsolved problem is the presence of He II nebular emission in many low-metallicity star-forming galaxies. This emission requires ionising photons with an energy > 54 eV; it is important to note that these particular photons are not produced in sufficient amounts by normal stellar populations. Aims. To examine if high mass X-ray binaries and ultra-luminous X-ray sources (HMXBs and ULXs) can explain the observed He II nebular emission and how their presence alters other emission lines, we computed photoionisation models of galaxies including such sources. Methods. We combined spectral energy distributions (SEDs) of integrated stellar populations with constrained SEDs of ULXs to obtain composite spectra with varying amounts of X-ray luminosity, parameterised by LX/SFR. With these, we computed photoionisation models to predict the emission line fluxes of the optical recombination lines of H and He+, as well as the main metal lines of [O III], [O II], [O I], and [N II]. The predictions were then compared to a large sample of low-metallicity galaxies. Results. We find that it is possible to reproduce the nebular He II λ4686 and other line observations with our spectra and with amounts of LX/SFR compatible with the observations. Our work suggests that HMBXs and ULXs could be responsible for the observed nebular He II emission. However, the strengths of the high and low ionisation lines, such as He II and [O I] λ6300, strongly depend on the X-ray contribution and on the assumed SEDs of the high energy source(s), the latter being poorly known.

Effects of Atmospheric Attenuation on the Lightning Spectrum

AbstractSpectrum carries important information reflecting atomic and molecular processes inside a light source. Accurate spectral diagnosis is vital in revealing the microscopic physical mechanism of the lightning discharge process. Spectral correction was applied considering the influence of atmospheric attenuation, grating efficiency, and camera response on the observed spectrum, thereby solving the problems of atmospheric attenuation in long‐distance lightning spectrum observations. Based on the restored spectrum, the temperature of the lightning return stroke channel was calculated by the ionic and atomic lines respectively. The result showed that corrected temperature at the initial stage of the return stroke, calculated by the ionic line, could reach up to 40,000 K, which was about 10,000 K higher than the values directly obtained from the observed spectrum. Atmospheric attenuation of the atomic spectral line in the near‐infrared band is relatively weak; therefore, atmospheric attenuation was inferred to have a relatively less effect on the channel temperature that was calculated by the atomic spectral lines. This work provided the attenuation ratio of the characteristic lines in lightning spectra with distance, and can used for more precisely quantitative investigation on the physical characteristics of the lightning process. It also has application value for improving the spectral diagnostic techniques on celestial body and other natural luminous process.

Plasma parameters of Au nano-particles ablated on porous silicon produced via Nd-YAG laser at 355 nm for sensing NH3 gas

The current study aimed the syntheses and characterizations of Gold nanoparticles (Au NPs) using a laser ablation Q-switched Nd: YAG laser with a wave-length of 355 nm at a variety of laser pulse energies (E) and deposited on porous silicon (PS). Optical emission spectrometer was used to diagnosed medium air to study gold plasma characteristics and prepared Au nanoparticles. The laser pulse energy influence has been studied on the plasma characteristics in air. The data showed the emergence of the ionic (Au II) spectral emission lines in the gold plasma emission spectrum. XRD has been utilized to examine structural characteristics. Moreover, AFM results 37.2 nm as the mean value of the diameter that is coordinated in a shape similar to the rod that appears for Au NPs, in addition to that, TEM has been an indication of the fact that synthesized Au NPs were spherical with a mean size of particles, ranging from 25 nm to 30 nm. At high laser pulse energy, the intensity of all emission peaks in the air at atmospheric pressure was considerably greater. Finally, variations in the operating temperature associated with the NH3 gas sensor, created from the samples that have been prepared on the sensitivity of the sensor and response time have been evaluated, the maximal sensitivity is nearly 41% concerning Au NPs that have been ablated via laser energy (E) 400 mJ on the porous silicon of the NH3 gas.

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.