Intensities Of Emission Lines Research Articles

Laser-induced breakdown spectroscopy for helium detection in beryllium coatings

Laser Induced Breakdown Spectroscopy (LIBS) method is considered to be a promising tool for analyzing the retention of hydrogen isotopes (D and T) and helium (He) on the first walls and divertor regions of future fusion reactors. Helium will be produced in DT reactions but could also be used in the initial non-nuclear phases of DEMO concepts. The present study investigates the He detection by LIBS method in the Be coatings simulating the deposits on the divertor plasma-facing components of JET while the results are also relevant for He detection in the deposits of other wall materials. The study was carried out in a vacuum vessel filled with 2–40 mbar argon background gas. It was shown that 2.8 at. % of He was confidently detectable by LIBS at optimized measurement conditions and the estimated limit of detection at used experimental conditions is approximately 0.7 at. %. The intensity of the He emission line at 587.56 nm was the strongest at the center of the laser-induced plasma plume. The He line intensity increased with the pressure of Ar gas but the broadening of the He line and the increase of the background emission and noise set an upper limit to the Ar background pressure usable for He detection. The application of the calibration-free LIBS procedure resulted in the overestimation of the He/Be ratio by several orders of magnitude. The overestimation can be explained by the deviation of LIBS plasma from the local thermodynamic equilibrium, which is caused by the very high excitation energy of He atoms.

Detection and diagnosis of bacterial pathogens in urine using laser-induced breakdown spectroscopy

The presence of bacterial cells from three species has been detected in clinical specimens of human urine using laser-induced breakdown spectroscopy (LIBS) by using a partial least squares discriminant analysis (PLS-DA) of 360 spectra obtained from 12 specimens of infected urine and 239 spectra obtained from eight specimens of sterile urine. Nominally sterile urine specimens obtained from four patients at a local hospital after being screened negative for the presence of bacterial pathogens were spiked with known aliquots of Escherichia coli, Staphylococcus aureus, and Enterobacter cloacae to simulate clinical urinary tract infections. Fifteen emission line intensities measured from the LIBS spectra and 92 ratios of those line intensities were used as 107 independent variables in the PLS-DA for discrimination between bacteria-containing specimens and sterile specimens. The PLS-DA models possessed a 98.3% sensitivity and a 97.9% specificity for the detection of pathogenic cells in urine when single-shot LIBS spectra were tested. To increase the signal to noise ratio, thirty spectra acquired from a single specimen were also averaged together and the averaged spectra were used to construct a model. When each averaged spectrum was withheld from the model individually for testing, the diagnostic test possessed a 100% sensitivity and a 100% specificity for the detection of bacterial cells in urine, although the number of test spectra was necessarily reduced.The entire LIBS spectrum from 200 nm – 590 nm was input into an artificial neural network analysis with principal component analysis pre-processing (PCA-ANN) to diagnose the bacterial species once detected. This PCA-ANN test possessed an overall sensitivity of 97.2%, an overall specificity of 98.6%, and an overall classification accuracy of 97.9% when using 80% of the data to build a model and withholding 20% for cross-validation testing. The PCA-ANN was also performed on each of the 12 bacteria-containing filters individually, using the other 11 filters to build the model. The average sensitivity of this test, calculated by averaging the sensitivities measured for each of the three bacterial species, was 70.9% and the average specificity was 85.5%. Based on these results, the average classification accuracy for the test when used to discriminate between the three microorganisms was 80.6%. These results indicate the potential usefulness of LIBS for rapidly detecting and possibly diagnosing urinary tract infections in a clinical setting.

Influence of the RF voltage amplitude on the space- and time-resolved properties of RF–LF dielectric barrier discharges in α–γ mode

This work reports the results of an experimental and modeling study on dual-frequency Ar–NH3 dielectric barrier discharges (DBDs) exhibiting the α–γ transition. A combination of space- and time-resolved optical absorption and emission spectroscopy is used to record spatio-temporal mappings of the Ar metastable number density, Ar 750.4 nm line emission intensity, and electron–Ar bremsstrahlung continuum emission intensity. With the increase of the radio frequency (RF) voltage amplitude in a 50 kHz–5 MHz DBD, maximum populations of Ar excited species (1s and 2p states, linked to the population of high-energy electrons) observed in the γ mode decrease and appear earlier in the low-frequency cycle. On the other hand, the density of the bulk electrons, monitored from the continuum emission intensity, increases, with a more prominent rise in the RF-α mode than in the γ regime. Such behaviors are consistent with the predictions of 1D fluid model and results from a decrease of the gas voltage required for self-maintenance of the cathode sheath in the γ breakdown.

Evolution of the relation between the mass accretion rate and the stellar and disk mass from brown dwarfs to stars

The time evolution of the dependence of the mass accretion rate with the stellar mass and the disk mass represents a fundamental way to understand the evolution of protoplanetary disks and the formation of planets. In this work, we present observations with X-shooter of 26 Class II very low-mass stars (< 0.2 M⊙) and brown dwarfs in the Ophiuchus, Chamaeleon-I, and Upper Scorpius star-forming regions. These new observations extend the measurement of the mass accretion rate down to spectral type (SpT) M9 (∼0.02 M⊙) in Ophiuchus and Chamaeleon-I and add 11 very-low-mass stars to the sample of objects previously studied with broadband spectroscopy in Upper Scorpius. We obtained the spectral type and extinction, as well as the physical parameters of the sources. We used the intensity of various emission lines in the spectra of these sources to derive the accretion luminosity and mass accretion rates for the entire sample. Combining these new observations with data from the literature, we compare relations between accretion and stellar and disk properties of four different star-forming regions with different ages: Ophiuchus (∼1 Myr), Lupus (∼2 Myr), Chamaeleon-I (∼3 Myr), and Upper Scorpius (5−12 Myr). We find the slopes of the accretion relationships (L* − Lacc, M∗ − Ṁacc) to steepen in the 1−3 Myr age range (i.e., between Ophiuchus, Lupus, and Chamaeleon-I) and that both relationships may be better described with a single power law. We find that previous claims for a double power-law behavior of the M∗ − Ṁacc relationship may have been triggered by the use of a different SpT–Teff scale. We also find the relationship between the protoplanetary disk mass and the mass accretion rate of the stellar population to steepen with time down to the age of Upper Scorpius. Overall, we observe hints of a faster evolution into low accretion rates of low-mass stars and brown dwarfs. At the same time, we also find that brown dwarfs present higher Mdisk/Ṁacc ratios (i.e., longer accretion depletion timescales) than stars in Ophiuchus, Lupus, and Cha-I. This apparently contradictory result may imply that the evolution of protoplanetary disks around brown dwarfs may be different than what is seen in the stellar regime.

Chemical abundances of LINER galaxies – nitrogen abundance estimations

ABSTRACT In this work, we investigated the nitrogen and oxygen abundances in a sample of galaxies with Low Ionization Nuclear Emission Regions (LINERs) in their nucleus. Optical spectroscopic data (3600 – 10 000 Å) of 40 LINERs from the Mapping Nearby Galaxies (MaNGAs) survey were considered. Only objects classified as retired galaxies, that is, whose main ionization sources are post-Asymptotic Giant Branch (pAGB) stars, were selected. The abundance estimates were obtained through detailed photoionization models built with the cloudy code to reproduce a set of observational emission line intensities ratios of the sample. Our results show that LINERs have oxygen and nitrogen abundances in the ranges of $\rm 8.0 \: \lesssim \: 12+\log (O/H) \: \lesssim \: 9.0$ (mean value 8.74 ± 0.27) and $\rm 7.6 \: \lesssim \: 12+\log (N/H) \: \lesssim \: 8.5$ (mean value 8.05 ± 0.25), respectively. About 70 per cent of the sample have oversolar O/H and N/H abundances. Our abundance estimates are in consonance with those for Seyfert 2 nuclei and H ii regions with the highest metallicity, indicating that these distinct object classes show similar enrichment of the interstellar medium (ISM). The LINERs in our sample are located in the higher N/O region of the N/O versus O/H diagram, showing an unexpected negative correlation between these two parameters. These results suggest that these LINERs mainly exhibit a secondary nitrogen production and could be acting some other mechanisms that deviate them from the usual theoretical secondary nitrogen production curve and the H ii regions observations. However, we did not find any evidence in our data able to support the literature suggested mechanisms. Alternatively, our results show that LINERs do not present any correlation between the N/O abundances and the stellar masses of the hosting galaxies.

Hyperspectral imaging of a microwave argon plasma jet expanding in ambient air.

Non-equilibrium plasmas at atmospheric pressure are often characterized by optical emission spectroscopy. Despite the simplicity of recording optical emission spectra in plasmas, the determination of spatially resolved plasma properties (e.g., electron temperature) in an efficient way is very challenging. In this study, spatially resolved optical images of a microwave argon plasma jet expanding into the ambient air are recorded over a wide range of wavelengths using a hyperspectral imaging system based on a tunable Bragg-grating imager coupled to a scientific complementary metal-oxide-semiconductor camera. The system's working principle is detailed, along with the necessary post-processing steps. Further analysis of the spatial-spectral data, including the Abel transform used to determine 2D radially resolved spatial mappings, is also presented. Overall, the proposed approach provides unprecedented cartographies of key plasma parameters, such as argon and oxygen line emission intensities, Ar metastable number densities, and argon excitation temperatures. Considering that all these plasma parameters are obtained from measurements performed in a reasonable time, Bragg-grating-based hyperspectral imaging constitutes an advantageous plasma diagnostic technique for detailed analysis of microwave plasma jets used in several applications.

Isotopic analysis of uranium at the picogram level with single-shot laser induced breakdown spectroscopy

Uranium was measured by laser induced breakdown spectroscopy (LIBS) with a limit of detection of 1.3 picograms with spectral-peak height as the analytical parameter, which shows an improvement of several orders of magnitude compared to other reports in the literature. The improvement is a result of optimizing the choice of the U analytical line, the system hardware, and the light collection and detection efficiency. The research established properties of U line emission (intensity, signal-to-background ratio, isotopic splitting, and spectral interferences) to select an optimum wavelength for analysis. The samples were mock particles from dried, monodispersed U solution droplets (∼65 pL in volume) deposited on Si wafers. LIBS emission spectra from several 235U-enriched samples were measured to demonstrate the performance for isotopic analysis. For isotopic measurements, two masses for total U, 100 pg and 325 pg, were studied. The 235U: 238U isotopic ratio was obtained by peak fitting the LIBS spectra without requiring calibration with the use of enriched standards. Depending on the total U mass and the 235U enrichment, typical relative standard deviations of the isotopic analysis ranged from several percent down to about 1%. Further, the developed method and the reported analytical performance were all based on single-shot LIBS. Overall, the study highlights the potential of LIBS as a robust and sensitive technique for isotopic analysis of U-containing particles.

Emission Line Intensity Ratios of Fe xxvi/ xxv/ xxiv in Solar Flares Observed by Hinotori

High-resolution spectra observed by the Solar X-ray spectrometer on board the Hinotori mission are revisited. Flat crystals slightly offset to the satellite spin axis produce automatic spectral scans for emission lines emerging from highly charged iron ions in solar flares every half-spin time period. All the downlinked data of the mission are converted to FITS format and major flare spectral data are revived as IDL save files in ISAS/DARTS. Based on these data sets, single-temperature fits are performed for the emission line complex of highly charged iron ions in the wavelength range of 1.75–1.95 Å and compared with theoretical predictions. Synthetic spectra with single electron temperatures estimated from j/w line-intensity ratios fit fairly well for Fe xxiv and Fe xxiii lines in the wavelength range of 1.85–1.88 Å, while intensity ratios of Fe xxv lines (x, y, z) and the inner-shell excitation line of Fe xxiv (q) to the Fe xxv resonance line (w) have systematic excesses. Empirical relations for the observed line ratios are derived. Ion fractions of Fe+25/Fe+24 estimated by intensity ratios of Lyα/w in the temperature range of log T e =7.25–7.45 are consistent with values in ionization equilibrium, and the remaining excesses of the Fe xxv line ratios may suggest problems with the atomic parameters or atomic modeling.

Application of helium line intensity ratio spectroscopy to xenon plasma in E × B Penning discharge

We propose the application of helium line intensity ratio spectroscopy in a low-pressure (0.3 mTorr) xenon E × B discharge with an electron temperature of ∼2 eV and a density of 1010−1011cm−3 . We successfully identified the helium atom line emissions at 388.9, 447.1, 501.6, 504.8, and 706.5 nm with helium pressures of up to ∼20 mTorr. The measured electron temperature, density, and I−V characteristics of the discharge remained almost constant in all helium pressures in the present experiment, indicating the suitability of the helium gas as a diagnostic gas. The results of helium line intensity ratio spectroscopy using the line emissions at 388.9, 447.1, and 504.8 nm showed fair agreement with the Langmuir probe measurement. Considering the trade-off relationship between the disturbance introduced by the helium gas and the signal-to-noise ratio, we conclude that a helium pressure of approximately 4 mTorr (approximately 13 times the partial pressure of xenon) represents the optimal pressure range for the application of the helium line emission intensity ratio method to this xenon plasma. It is found that the use of the line emissions at 501.6 and 706.5 nm result in a significant disturbance in the helium line intensity ratio method due to the radiation trapping effect.

In-situ monitoring of Al/Cu dissimilar laser welding process using optical emission spectroscopy (OES)

Aluminum (Al) and copper (Cu) dissimilar laser welding is an in-demand process in the manufacture of secondary battery systems for electric vehicles. However, the absence of a robust in-situ monitoring technique for this process reduces its efficiency and increases the potential risk to the battery system. Laser-induced plasma (LIP) has been extensively studied in various laser processes because it provides crucial information regarding the interaction between the laser beam and material. In this study, the measurement of LIP was conducted using optical emission spectroscopy (OES) during the Al and Cu dissimilar welding process to gain a comprehensive understanding of the process. Moreover, the feasibility of OES as a monitoring tool for dissimilar laser welding of Al and Cu was evaluated. Plasma parameters such as emission line intensity, electron temperature, and number density were effectively used to diagnose the welding state (non-welding, threshold welding, or Cu-penetrated welding). In addition, a strong correlation between the weld geometry and intensity of the Cu emission line was found. This study demonstrates the considerable potential of OES-based in-situ monitoring system applicable for high-demand dissimilar laser welding processes.

A new method for calibration-free analysis by Laser-Induced Breakdown Spectroscopy using a time-integrated spectrometer

In this paper, we will discuss a new method for obtaining information about the plasma temporal evolution in Laser-Induced Breakdown Spectroscopy (LIBS) experiments using a time-integrated spectrometer.The method, inspired to the Bredice 3D-Boltzmann plot formalism, allows a precise determination of the temporal evolution of the emission line intensity in a LIBS plasma, starting from a series of time-integrated measurements obtained at different delay times after the laser pulse.In this way the application of a calibration-free algorithm using a time-integrated spectrometer is made possible.Examples of the application of the method are given in the analysis of two Zamac (a zinc alloy containing aluminum, magnesium, and copper) certified samples. A good agreement is obtained between the calculated and nominal concentrations of the two samples.A further validation of the method was performed on a third Zamac sample, of unknown composition. The sample was first characterized using a conventional CF-LIBS approach on a time-resolved spectrum; the obtained composition was then compared with the one determined using the series of time-integrated spectra.

Frequency-locked measurement of floating potential fluctuations in cold micro-plasma jets: Interactive surface feedback effects on reactive species generation

Frequency-locked measurements of floating potential fluctuations are carried out in a cold atmospheric pressure micro-plasma jet interacting with substrates of varying electrical permittivity (εr). The range of fluctuation frequencies (∼ 0.5–9 kHz) is compared with that determined from the time series of floating potential fluctuations and its fast Fourier transform. Results of these independent methods to determine the fluctuation frequencies are found to agree reasonably well, thereby affirming their existence in the micro-plasma jet. Substrate feedback effects dictated by εr are found to influence the amplitude of fluctuations and threshold breakdown voltage. The spectral emission line intensity corresponding to the reactive oxygen and nitrogen species, which is critical for biomedical applications, decrease drastically in the presence of stronger levels of fluctuations, indicating a bearing on their generation.

Vertical Wind Profiles in the Mesosphere and Lower Thermosphere Driven by Meteor Radar and Ionospheric Connection Explorer Observations Over the Korean Peninsula

AbstractMeteor radar observations provide wind data ranging from 80 to 100 km altitude, while the Michaelson Interferometer for Global High‐resolution Thermospheric Imaging (MIGHTI) onboard the Ionospheric Connection Explorer satellite offers wind data above 90 km altitude. This study aims to generate wind profiles in the mesosphere and lower thermosphere by combining the winds derived from meteor radar and MIGHTI observations over the Korean Peninsula from January 2020 to December 2021. The wind profiles derived from the two instruments are continuous at night, but they show discrepancies during the day. The atomic oxygen 557.7 nm (green line) emission intensity measured by MIGHTI peaks at approximately 100 km during the day and 94 km at night. The vertical gradient of the airglow volume emission rate is more pronounced during the day. These differences can cause day‐night differences in the MIGHTI wind retrieval accuracy, potentially leading to discrepancies during the day.

Color-tunable luminescence and temperature sensing properties of Bi3+/Sm3+ or Bi3+/Eu3+ codoped Ba2Gd2Ge4O13 phosphors.

Novel temperature-sensitive luminescent materials, Ba2Gd2Ge4O13 doped with Bi3+, Bi3+/Sm3+ or Bi3+/Eu3+ ions, have been prepared using a conventional solid-state reaction technique. The XRPD study has verified that all the synthesized germanates crystallize in the monoclinic system (space group C2/c, Z = 4). The crystal lattice of the compounds consists of zigzag chains of edge-sharing Me2O7 (Me = Bi3+, Eu3+ or Sm3+) dimers, [Ge4O13] units, and ten-coordinated Ba atoms. Under UV excitation the powders exhibit the luminescence corresponding to the 3P1 → 1S0 (310-550 nm) transition in Bi3+ and 4G5/2 → 6HJ (550-730 nm) in Sm3+ or 5D0 → 7FJ (570-720 nm) transitions in Eu3+ ions. Heating of Ba2Gd1.94Bi0.01Sm0.05Ge4O13 and Ba2Gd1.89Bi0.01Eu0.1Ge4O13 phosphors leads to an irregular decrease in the intensity of the main emission lines. It has been found that the fluorescence intensity ratio between a wide band in the 310-530 nm region and peaks at longer wavelengths may be successfully used as a temperature-dependent characteristic. Absolute/relative sensitivity values for Ba2Gd1.94Bi0.01Sm0.05Ge4O13 and Ba2Gd1.89Bi0.01Eu0.1Ge4O13 germanates reach 0.19% K-1/0.80% K-1 and 2.21% K-1/0.58% K-1, respectively. The above parameters indicate that Ba2Gd2Ge4O13:Bi3+/Sm3+ or Bi3+/Eu3+ samples can be used as potential luminescent materials for non-contact temperature measurement.

Extreme N-emitters at high redshift: Possible signatures of supermassive stars and globular cluster or black hole formation in action

Context. Recent James Webb Space Telescope (JWST) spectroscopic observations of the z = 10.6 galaxy GN-z11 have revealed a very peculiar UV spectrum exhibiting intense emission lines of nitrogen, which are not typically detected in galaxy spectra. This observation indicates a super-solar N/O abundance ratio at low metallicity, which only resembles the abundances seen in globular cluster (GC) stars. This discovery suggests that we might be seeing proto-GCs in formation or possibly even signatures of supermassive stars. Aims. To examine whether other objects with strong N IV and/or N III emission lines (N-emitters, hereafter) exist and to better understand their origin and nature, we have examined the available JWST spectra and data from the literature. Methods. Using the NIRSpec/JWST observations from CEERS, we found an extreme N-emitter, CEERS-1019 at z = 8.6782, showing intense N IV] λ1486 and N III] λ1750 emission. From the observed rest-UV and optical lines, we conclude that it is compatible with photoionization from stars and we have determined accurate abundances for C, N, O, and Ne, relative to H. We also (re-)analyzed other N-emitters from the literature, including three lensed objects at z = 2.3 − 3.5 (Sunburst cluster, SMACS2031, and Lynx arc) and a low-redshift compact galaxy, Mrk 996. We carried out a comparison among the observed abundance ratios to observations from normal star-forming galaxies, predicted wind yields from massive stars, and predictions from supermassive stars (SMS with ∼104 − 105M⊙). Results. For CEERS-1019, we find a highly supersolar ratio log(N/O)= − 0.18 ± 0.11, and abundances of log(C/O)= − 0.75 ± 0.11 and log(Ne/O)= − 0.63 ± 0.07, which are normal compared to other galaxies at the low metallicity (12 + log(O/H) = 7.70 ± 0.18) of this galaxy. The three lensed N-emitters also show strongly enhanced N/O ratios and two of them normal C/O. The high N/O abundances can be reproduced by massive star winds assuming a special timing and essentially no dilution with the ambient interstellar medium (ISM). Alternatively, these N/O ratios can be explained by mixing the ejecta of SMS with comparable amounts of unenriched ISM. Massive star ejecta (from WR stars) are needed to explain the galaxies with enhanced C/O (Lynx arc, Mrk 996). On the other hand, a SMS in the “conveyer-belt model” (put forward to explain globular clusters) would predict a high N/O and small changes in C/O, compatible with CEERS-1019, the Sunburst cluster, SMACS2031, and GN-z11. Based on the chemical abundances, possible enrichment scenarios, and other properties (e.g., their compactness and high ISM density), we discuss which objects could contain proto-GCs. We suggest that this is the case for CEERS-1019, SMACS2031, and the Sunburst cluster. Enrichment in the Lynx arc and Mrk 996 is likely due to normal massive stars (WR), which implies that the star-forming regions in these objects cannot become GCs. Finally, we propose that some N-emitters enriched by SMS could also have formed intermediate mass black holes and we suggest that this might be the case for GN-z11. Conclusions. Our observations and analysis reinforce the suggested link between some N-emitters and proto-GC formation, which is supported both by empirical evidence and quantitative models. Furthermore, the observations provide possible evidence for the presence of supermassive stars in the early Universe (z > 8) and at z ∼ 2 − 3. Our analysis also suggests that the origin and nature of the N-emitters is diverse, including objects such as GN-z11, which may possibly host an active galactic nucleus (AGN).

Hyperspectral imaging and TRI3DYN simulation study of physical sputtering from a fuzzy surface

The influence of a fuzzy surface on the physical sputtering of Mo in He plasmas has been studied with hyperspectral imaging (HSI) measurements and simulations that couple the TRI3DYN code with an impurity transport code. The 2D profiles of the Mo I line emission intensity from HSI images reveal that the sputtering yield, Y, is reduced to ∼40 % of the smooth-surface value due to the presence of a fuzz layer, while the angular distribution of the sputtered Mo atoms might not change significantly. The simulations reproduce the Y reduction successfully, but indicate that fuzz causes an increase in the small-angle distribution of sputtered atoms. However, the increase is too small to produce an observable change in the Mo I emission profiles. A simple analytical model that assumes a single collision mean free path for a fuzz layer and considers only the primary sputtering events qualitatively reproduces the Y reduction and the small-angle distribution enhancement, explaining the geometrical effect of fuzz on physical sputtering.

NATURE OF ZINC OXIDE COLLOIDAL NANOCRYSTALS PHOTOLUMINESCENCE

The purpose of the study is to determine the nature of the radiative transitions responsible for the visible radiation of zinc oxide nanocrystals. Show that the size of nanocrystallites does not affect the spectral composition and location of long-wave luminescence. ZnO nanocrystals obtained by the method of colloidal synthesis with or without gelatin stabilization were investigated in the paper. The size of the nanocrystallites was determined in the approximation of the effective masses by the magnitude of the fundamental absorption edge shift. The results of calculating the size of nanocrystallites agree well with the results of SEM studies. It is shown that the main factor affecting the size of nanocrystallites is the concentration of precursors. Photoluminescence spectra of colloidal ZnO nanocrystals were studied in two spectral regions – ultraviolet and visible. Photoluminescence spectra in the ultraviolet region are characterized by three emission lines, the location of which depends on the concentration of precursors, that is, on the width of the band gap. Analysis of the energy states of intrinsic defects in nanostructured zinc oxide showed that the first two emission lines are associated with radiative transitions of excitons bound on neutral interstitial zinc atoms and on neutral zinc vacancies. The third line of ultraviolet radiation is caused by radiative transitions with the participation of deep donors, which are interstitial zinc atoms in the +2 charge state. The visible radiation spectra of colloidal ZnO nanocrystals are characterized by broad non-elemental emission bands in the blue-green and yellow-red regions of the spectrum. A detailed analysis of the spectra at different concentrations of precursors showed that the change in concentrations of precursors does not affect the spectral location of elementary emission lines. The absence of impurity absorption lines indicates that the centers responsible for visible radiation are donor-acceptor pairs. The analysis of the ratio of the emission lines intensities with increasing concentrations of the precursors shows that interstitial zinc and oxygen atoms dominate in the studied nanocrystals at high concentrations. As a result, in samples with a high concentration of precursors, blue radiation dominates over yellow and green. Thus, the study shows that by changing the concentrations of precursors, it is possible to influence both the spectral location of the edge ultraviolet luminescence and the intensity of individual long-wave luminescence components. The resulting colloidal ZnO nanocrystals can be used as luminescent sensors.

KAgoshima Galactic Object survey with Nobeyama 45 m telescope by Mapping in Ammonia lines (KAGONMA): Discovery of parsec-scale CO depletion in the Canis Major star-forming region

Abstract In observational studies of infrared dark clouds, the number of detections of CO freeze-out on to dust grains (CO depletion) at the pc scale is extremely limited, and the conditions for its occurrence are, therefore, still unknown. We report a new object where pc-scale CO depletion is expected. As part of the Kagoshima Galactic Object survey with Nobeyama 45 m telescope by Mapping in Ammonia lines (KAGONMA), we have made mapping observations of NH3 inversion transition lines towards the star-forming region associated with Canis Major OB1, including IRAS 07077−1026, IRAS 07081−1028, and PGCC G224.28−0.82. By comparing the spatial distributions of NH3 (1,1) and C18O (J = 1–0), an intensity anti-correlation was found in IRAS 07077−1026 and IRAS 07081−1028 on the ∼1 pc scale. Furthermore, we obtained a lower abundance of C18O at least in IRAS 07077−1026 than in the other parts of the star-forming region. After examining high-density gas dissipation, photodissociation, and CO depletion, we concluded that the intensity anti-correlation in IRAS 07077−1026 is due to CO depletion. On the other hand, in the vicinity of the center of PGCC G224.28−0.82, the emission line intensities of both NH3 (1,1) and C18O (J = 1–0) were strongly detected, although the gas temperature and density were similar to IRAS 07077−1026. This indicates that there are situations where C18O (J = 1–0) cannot trace dense gas on the pc scale and implies that the conditional differences in which C18O (J = 1–0) can and cannot trace dense gas are unclear.

Characterization of Magnetized-Plasma System Induced by Laser

This study investigated the effect of applying an external magnetic field on the characteristics of laser-induced plasma, such as its parameters plasma, magnetization properties, emission line intensities, and plasma coefficients, for plasma induced from zinc oxide: aluminum composite (ZO:AL) at an atomic ratio of 0.3 %. Plasma properties include magnetization and emission line intensities. The excitation was done by a pulsed laser of Nd:YAG with 400 mJ energy at atmospheric pressure. Both the electron temperature and number density were determined with the help of the Stark effect principle and the Boltzmann-Plot method. There was a rise in the amount of (ne) and (Te) that was produced by applying a magnetic field and, on the other hand, using the 532 nm wavelength rather than the fundamental wavelength of a laser. The emission lines in the atmosphere's plasma have an appearance of Lorentzian shape. The 532 nm laser exhibited a decrease in both the Larmor radius and the confinement factor compared with the 1064 nm laser. By applying the magnetic field, the Laser Induced Breakdown Spectroscopy (LIBS) intensities increased by 1.44 times when compared to the emissions before applying the field. In addition, the spectral line intensities improved with the fundamental wavelength compared to the second harmonic frequency as a result of the increase in the extracted materials. This is due to the increase in the absorbance of the laser by the target, as some of these materials are excited, so they act as emission sources, which makes them more detectable.

Impact of intensity error on temperature estimation in laser-induced breakdown spectroscopy: a numerical study

Laser-induced breakdown spectroscopy (LIBS) is a cutting-edge technique for the compositional analysis of multi-element materials. Under standard circumstances for laser-induced plasma (T e = 1 eV and N e = 1016 cm−3), we simulated the emission spectrum of a binary alloy (with 70 wt.% Cu–30 wt.% Al). We used the Saha ionization equilibrium formulas to calculate the population of neutral and ionized species of each constituent element, and the Boltzmann distribution to estimate the intensities of emission lines with radiative transition probabilities. The Stark broadening equation is then used to determine the line broadening, yielding a Lorentzian profile for each line. The sum of line emissions of all constituent species will approximate the alloy’s LIBS spectra in an assumption of ideal analytical plasma. Then, we generated random errors in the intensities of spectral lines ranging from 5% to 35%. To investigate temperature estimation accuracy, we utilized three well-established approaches: the Boltzmann plot (BP) method, the Saha–Boltzmann plot (SBP) method, and the Multi-elemental SBP (MESBP) method. As intensity error increases from 5% to 35%, the estimated temperature in the BP method deviates from 0.25% to 18.3%. Whereas the intensity error is almost unaffected using the SBP method and the MESBP method. The temperature deviation is less than 2% in both situations. This study is relevant to calibration-free LIBS, in which the exact temperature determination is crucial for the abundance estimation of trace, major, and minor elements.