Detection Of Optical Emission Research Articles

Discovery of optical emission from the supernova remnant G108.2−0.6 and its atomic environment

ABSTRACT We report on the first detection of optical emission from the shell-type Galactic supernova remnant (SNR) G108.2−0.6. We obtained Hα images and long-slit spectra using the 1.5-m RTT150 telescope to examine the morphological and spectral characteristics of the SNR. We detected several filaments along its north and south regions, which is consistent with its SNR nature. The spectra exhibit [S ii]/Hα ratios in the range of 0.4–1.1, indicating emission from shock-heated gas. The oxygen doublet emission lines [O i] λλ6300, 6363 detected in the south region also support the indicator of the presence of shocks. We estimate the electron density using the [S ii] 6716/6731 ratio ranging from 15 to 1800 cm−3. The spectra show a relatively low shock velocity of Vs ∼ 80 km s−1 with the pre-shock cloud density of nc ∼18–57 cm−3. The Hα/Hβ ratios show significant variation across the observed regions with extinction E(B − V) ranging from 0.22 to 1.65. We also analysed the archival H i data and estimated the kinematic distance to G108.2−0.6 of ∼0.8 kpc and its dynamical age as ∼70 ± 10 kyr.

Detection of optical emission from the supernova remnant G7.7–3.7

ABSTRACT We present the first optical study of the supernova remnant (SNR) G7.7–3.7, with the aim of determining its evolutionary phase since it has been suggested to be the remnant of SN 386 AD. We obtained narrow-band images in the filters H α + [N ii], H β, [O iii], [S ii] that revealed faint optical emission in the southern region of the SNR consisting of two filaments elongated in the east–west direction aligned with the X-ray emitting region of the remnant. The filaments were seen in H α + [N ii], [O iii] images and marginally in the [S ii] images, with a non-detection in H β. Long-slit spectroscopy of the three regions along one filament revealed large ratios of [S ii]/H α = (1.6–2.5), consistent with that expected for a shock-heated SNR. The [S ii] doublet ratio observed in two of the regions implies an upper limit for the electron density of the gas, with estimates falling below 400 cm−3 and 600 cm−3 in the respective areas. We discuss potential physical mechanisms that formed the observed optical filaments and we suggest that most likely they resulted by a collision of the SNR with a dense circumstellar shell lying at the southern region of the remnant.

Detection Method of Partial Discharge on Transformer and Gas-Insulated Switchgear: A Review

The detection of partial discharge (PD) activities in high-voltage equipment can be conducted according to several mechanisms of signal detection, including electromagnetic wave signal detection, acoustic signal detection, chemical reactions, electrical signal detection, and optical emission detection. Recently, multiple methods of detection and localization of partial discharge activities, which occurred in power transformers and gas-insulated switchgear (GIS), have been proposed to monitor the health condition of high-voltage equipment, especially when the awareness regarding preventive maintenance has been emphasized at the industrial level and among electrical providers. In aligning the needs of the industrial sector and the improvement of PD-detection methods, this manuscript focuses on reviewing the current practice methods for the detection and localization of PD signals in high-voltage equipment, comparing their efficacy, and summarizing the future direction of research work-related methods of PD detection. The comparative reviews are discussed in terms of the mechanism of PD signal detection, indication parameters, calibration techniques, and the advantages and limitations of each method of PD measurement in detail.

Detection of optical emissions from deep localized states in a self-assembled InAs/GaAs QD structure

This work reports on the optical properties of self-assembled InAs/GaAs quantum dots (QDs) grown by molecular beam epitaxy. A sigmoidal temperature-dependent variation of the bandgap energy of the dots is detected from the photoluminescence (PL) investigations of the studied sample. This sigmoidal dependence of the bandgap energy was accompanied by an anomalous increase in the integrated PL intensity (IPLI) over the temperature range of 10 K to 110 K. Such optical observations are related to the existence of deep localized states (LS) within the QD structure. To illustrate the presence of the LS, pump power-dependent PL measurements at different temperatures were performed. It is found that the sigmoidal dependence of the PL peak energy (PLPE) gradually converts into a monotonous variation with the gradual increase in the excitation density. These observations show a saturation behavior of a limited number of states within the bandgap of the QDs. Such optical results provide clear evidence for the existence of deep levels within the InAs dots.

Trace Element Concentration and Stable Isotope Ratio Analysis in Blueberries and Bilberries: A Tool for Quality and Authenticity Control.

Vaccinium genus berries—wild bilberries (Vaccinium myrtillus L.) and cultivated highbush blueberries (Vaccinium corymbosum L.)—are consumed worldwide, and their consumption has a trend of stable increase. Thus, considering their wide use in ethnomedicine, for juice and jam production, as functional food, as well as their use in preparations of extracts which have application potential in pharmaceutical and cosmetics industries, studies regarding the composition of these berries are of special importance. The aim of this study is to characterise the elemental and isotopic composition, as well as variation in element concentration in bilberries gathered from different sites in Northern Europe and in commercially available blueberry samples from across the World. Furthermore, our aim was to develop tools for authenticity and quality control of these berries. The elemental composition of berries was analysed using inductively coupled plasma with optical emission detection (ICP-OED), while isotope ratio mass spectrometry (IRMS) was used for the determination of isotope ratio values. The results demonstrated detectable differences between macro- and microelement values in bilberries. IRMS analysis of blueberries revealed significant differences in isotope ratios based on the place of origin, indicating the possibility to use this analytical method for authenticity testing. In none of the samples, pollution was detected, even though there were indications of different growth conditions and geochemical differences affecting bilberry composition.

Evaluating compositional effects on the laser-induced combustion and shock velocities of Al/Zr-based composite fuels

Laser-induced air shock from energetic materials (LASEM) is a laboratory-scale method for assessing the microsecond and millisecond timescale performance of conventional military explosives. The technique has been combined with optical emission detection schemes to evaluate energy release during detonation and post-detonation timescales from the combustion of metal powders and mixtures of metal powders and explosives. Recently, Al/Zr reactive composite powders have been synthesized via high energy ball milling with the aim of decreasing ignition thresholds while simultaneously increasing overall combustion efficiency and burn time. Here, we utilize LASEM to evaluate micron-sized 3Al:2Zr, Al:Zr, and Al:3Zr fuel powders and compare their behavior to micron-sized Al powder, a commonly used explosive additive. We observed a rapid ignition of Al/Zr powders instead of the delayed ignition of the secondary deflagration cloud that is observed for pure Al. The composites also demonstrated longer burn times compared to Al particles of similar size. We also observed enhanced laser-induced shock velocities for the composite samples, implying increased energy release in the microsecond time regime compared to Al. In addition, we present LASEM data using Al/Zr mixed with trinitrotoluene (TNT), and associated CHEETAH calculations. As expected, adding pure Al to TNT lowers the laser-induced shock velocity, and we observe a further decrease of this velocity when using composite additives. The complex interplay of the metals with each other and the TNT reaction products is yet to be fully understood.

A study of archaeological pottery of Northeast India using laser induced breakdown spectroscopy (LIBS)

Abstract The objective of this work is to investigate the chemical composition of the archaeological potsherds from Northeast India. Laser breakdown spectroscopy (LIBS) and scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM-EDX) have been used to identify the chemical composition of potsherds. LIBS is a micro-destructive technique and based on the time resolved detection of optical emission of transient plasma. In archaeological science, application of LIBS has gained interest for its capability in atomic species recognition. Scanning electron microscope coupled with energy dispersive X-ray spectroscopy are powerful techniques to investigate the microstructure as well as the chemical composition of the archaeological ceramics. LIBS and EDX analyses have revealed that divergent quantities of Si, Al, Fe, Mg, Ti and K occurred as key constituent in the composition of analysed potsherds. The SEM-EDX results demonstrate that low refractory and non-calcareous clay have been used as raw material and the pottery was fired below 800 °C.

Detection of optical emission associated with the Galactic SNR G64.5+0.9

Detection of optical emission associated with the Galactic SNR G64.5+0.9

Dielectric Barrier Discharge Carbon Atomic Emission Spectrometer: Universal GC Detector for Volatile Carbon-Containing Compounds

It was found that carbon atomic emission can be excited in low temperature dielectric barrier discharge (DBD), and an atmospheric pressure, low power consumption, and compact microplasma carbon atomic emission spectrometer (AES) was constructed and used as a universal and sensitive gas chromatographic (GC) detector for detection of volatile carbon-containing compounds. A concentric DBD device was housed in a heating box to increase the plasma operation temperature to 300 °C to intensify carbon atomic emission at 193.0 nm. Carbon-containing compounds directly injected or eluted from GC can be decomposed, atomized, and excited in this heated DBD for carbon atomic emission. The performance of this new optical detector was first evaluated by determination of a series of volatile carbon-containing compounds including formaldehyde, ethyl acetate, methanol, ethanol, 1-propanol, 1-butanol, and 1-pentanol, and absolute limits of detection (LODs) were found at a range of 0.12-0.28 ng under the optimized conditions. Preliminary experimental results showed that it provided slightly higher LODs than those obtained by GC with a flame ionization detector (FID). Furthermore, it is a new universal GC detector for volatile carbon-containing compounds that even includes those compounds which are difficult to detect by FID, such as HCHO, CO, and CO2. Meanwhile, hydrogen gas used in conventional techniques was eliminated; and molecular optical emission detection can also be performed with this GC detector for multichannel analysis to improve resolution of overlapped chromatographic peaks of complex mixtures.

Laser-induced plasma and laser-induced breakdown spectroscopy (LIBS) in China: The challenge and the opportunity

Professor Ronger Zheng Laser-induced plasma as a spectroscopic emission source was introduced only two years after the invention of the laser. By focusing a pulse delivered by a ruby laser on the surface of a solid target, Brech and Cross in 1962 first observed optical emission following the laser impact [1], which later had been further identified as the emission from the plasma produced during the laser ablation process of the impacted target. Spectroscopic analysis of the plasma emission immediately demonstrated its huge potential for direct chemical analysis by showing a rich spectrum consisting of specific lines from ions, atoms as well as molecules in the ablation plume [2]. The simplicity of the original concept leads to the intrinsic advantages of the analytical technique developed later according to the above mentioned pioneer works and generally called nowadays, laser-induced breakdown spectroscopy (LIBS). The versatility of laser ablation process enables LIBS to directly analyze all kinds of materials, whether solid, liquid or gas. Sampling and excitation by laser pulse together with detection of optical emission are fully compatible with stand-off operation. On the other hand, the ability of a laser beam to be tightly focused provides microanalysis feature of the technique. Last but not least, LIBS shares multiple elemental analysis capability with other analytical techniques based on emission spectroscopy. Staying a laboratory curiosity up to the 1980’s, LIBS has found its first applications with the developments in Los Alamos conducted by Radziemski and Cremers on the detection of hazardous airborne trace metallic or nonmetallic elements [3, 4]. The development in the 1990’s was more spectacular thanks to the technological progresses realized in laser, in spectrometer and in detector [5]. The further development turned to resolve very practical problems, such as monitoring environmental contaminations [6], controlling industrial processes [7, 8], or sorting waste materials [9]. With the first international LIBS conference held in 2000 in Pisa, Italy, the international LIBS community was established with the specific missions to make LIBS a mature technology and to develop its applications. A much larger range of demands in various domains has stimulated the development of the technique. In a non-exhaustive list, we can cite analysis of art works and cultural heritages for their conservation [10]; detection and analysis of bacteria [11, 12] and explosives [13, 14] for the needs from national security and homeland defence; direct analysis of trace metallic elements in fresh vegetables [15]; geological studies [16]; application in the nuclear industry [17]; and finally the space exploration with the integration by the NASA of the LIBS module, ChemCam, in Curiosity rover for the analysis of the soil on the Mars [18, 19]. The widespread and rapid development of LIBS applications contrasts however with its actual status of “between science and mature technology” [5]. Such contrast can be considered in parallel with that existing between the conceptual simplicity of the LIBS technique and the complexity of the physical processes involved in laser ablation and in expansion of the produced plasma into ambient gas. The requirement of a quantitative analysis with high performance is actually the major challenge faced by the international LIBS community to mature the technique. Back to the fundamental in order to reach a deeper understanding of the laser-induced plasma is considered today

Optodynamic observation of double laser-induced breakdown at the water surface

A measurement technique based on the combination of beam deflection probe and photographic detection of optical emission is introduced for the study of laser-induced dielectric breakdown in the vicinity of the air–water interface. The plasma was photographed with a CCD camera and the shock wave generated by the breakdown in the air and inside the water was detected with a beam deflection probe as a function of the focus position. The comparative analysis of the photographic images and the characteristics of the simultaneously recorded ultrasonic signals shows that the amplitudes and the arrival times of the ultrasonic waves can reliably describe the characteristics of the breakdown and its position relative to the water surface. At certain focus positions the existence of double breakdown is evident.

Quantitative analysis by resonant laser ablation with optical emission detection: Resonant laser-induced breakdown spectroscopy

Resonant laser ablation (RLA) is a solid sampling technique that makes use of radiation trapping, and desorption induced by electronic transitions (DIET), to produce enhanced numbers of analyte atoms in the laser-induced plasma (LIP). This is achieved by tuning the laser ablation wavelength to a gas-phase resonant transition of the analyte. In this paper, RLA was coupled with detection of optical emission in the LIP to perform resonant laser-induced breakdown spectroscopic (RLIBS) experiments with a miniature, portable spectrometer. The experiments were designed to continue an examination of the proposed mechanism of RLA, and to perform an initial assessment of the applicability of RLIBS for quantitative analysis. The study indicated that for a multi-component sample, such as steel, the signal of the wavelength-targeted atom was enhanced the most compared to other constituents, and this supported the hypothesis that the DIET phenomenon is involved. Also, RLIBS experiments indicated that ablation yields of other components were enhanced by resonant ablation of the major component, which supported the contribution of radiation trapping to the RLA phenomenon. A linear, positive slope of the RLA induced atom yield as a function of concentration suggested that the RLA mechanism allows for quantitative analysis of solid samples. Calibration graphs were created for tungsten in spectrographic steels using RLIBS. A limit of detection of 4% was calculated for tungsten in steel.

The Dark Side of ROTSE‐III Prompt GRB Observations

Wepresent severalcasesofopticalobservationsduring � -raybursts(GRBs) whichresulted in promptlimitsbutno detection of optical emission. These limits constrain the prompt optical flux densities and the optical brightness relative to the � -ray emission. The derived constraints fall within the range of properties observed in GRBs with prompt optical detections, although at the faint end of optical/� -rayflux ratios. The currently accessible prompt optical limits do not require a different set of intrinsic or environmental GRB properties, relative to the events with prompt optical detections. Subject headingg gamma rays: bursts Online material: color figure

Detection of GRB 060927 atz= 5.47: Implications for the Use of Gamma‐Ray Bursts as Probes of the End of the Dark Ages

We report on follow-up observations of the gamma-ray burst GRB 060927 using the robotic ROTSE-IIIa telescope and a suite of larger aperture groundbased telescopes. An optical afterglow was detected 20 s after the burst, the earliest rest-frame detection of optical emission from any GRB. Spectroscopy performed with the VLT about 13 hours after the trigger shows a continuum break at lambda approx. equals 8070 A, produced by neutral hydrogen absorption at zeta = 5.6. We also detect an absorption line at 8158 A which we interpret as Si II lambda 1260 at zeta = 5.467. Hence, GRB 060927 is the second most distant GRB with a spectroscopically measured redshift. The shape of the red wing of the spectral break can be fitted by a damped Ly(alpha) profile with a column density with log(N(sub HI)/sq cm) = 22.50 +/- 0.15. We discuss the implications of this work for the use of GRBs as probes of the end of the dark ages and draw three main conclusions: i) GRB afterglows originating from zeta greater than or approx. equal to 6 should be relatively easy to detect from the ground, but rapid near-infrared monitoring is necessary to ensure that they are found; ii) The presence of large H I column densities in some GRBs host galaxies at zeta > 5 makes the use of GRBs to probe the reionization epoch via spectroscopy of the red damping wing challenging; iii) GRBs appear crucial to locate typical star-forming galaxies at zeta > 5 and therefore the type of galaxies responsible for the reionization of the universe.

Separation and Determination of Iron-Containing Proteins via Liquid Chromatography−Particle Beam/Hollow Cathode−Optical Emission Spectroscopy

Presented here is a method for the quantitative determination of iron-containing metalloproteins. Four iron-containing metalloproteins (transferrin, myoglobin, hemoglobin, and cytochrome c) were separated by high-performance liquid chromatography (HPLC) and determined through particle beam/hollow cathode-optical emission spectroscopy (PB/HC-OES) by the Fe (I) 371.9 nm optical emission. Parametric optimization of sample introduction, nebulization, and hollow cathode source conditions is performed for the suite of Fe-metalloproteins. Response curves for the Fe (I) emission were obtained under optimized conditions with detection limits for triplicate injections occurring on the nanogram level for iron ( approximately 24 ng) with variability of <7% RSD over the concentration range of 0.1-100 microg/mL iron in the metalloproteins. Response curves for S (I) emission yielded similar analytical characteristics. Optical emission detection of the liquid chromatography separations of the iron-containing metalloproteins demonstrates the feasibility of the PB/HC-OES system as a simple element-specific detector for liquid chromatography. The retention times of the four analytes are similar to those determined by UV absorbance (216 nm), demonstrating the ability of the PB interface to preserve the chromatographic integrity of the separation. Additionally, empirical formula calculations based on Fe (I) and S (I) emission response ratios provide a much higher level of specificity than single-element protein determination.

Determination of “free” iron and iron bound in metalloproteins via liquid chromatography separation and inductively coupled plasma-optical emission spectroscopy (LC-ICP-OES) and particle beam/hollow cathode-optical emission spectroscopy (LC-PB/HC-OES) techniques

The abilities of liquid chromatography-particle beam/hollow cathode-optical emission spectrometry (LC-PB/HC-OES) and liquid chromatography-inductively coupled plasma-optical emission spectroscopy (LC-ICP-OES) techniques are demonstrated for the quantitative determination of free iron and bound iron in metalloproteins. Separations were performed in the size exclusion and reversed-phase chromatographic modes. Myoglobin, holo-transferrin and iron(II) chloride were separated by size exclusion chromatography and the eluent species were detected by both PB/HC-OES and ICP-OES through the Fe I 259.9 nm and S I 180.7 nm optical emission. Sulfur optical emission was monitored as means of protein identification through the Fe/S empirical formula differences, with the absence of S emission used to identify the “free” Fe. Both techniques demonstrated detection limits for triplicate injections on the nanogram level for iron (0.9 ng mL−1 ICP-OES and 41.9 ng mL−1 PB/HC-OES) over the concentration range of 0.1 ng mL−1–100 μg mL−1 for iron and iron metalloproteins. The corresponding values for sulfur in the proteins were more similar for the two techniques, being of the order of 20 ng mL−1. The SEC retention times and peak shapes of the three analyte peaks for both techniques are similar to those determined by UV absorbance at 220 nm (Fe-containing metalloproteins) and conductivity (inorganic iron), demonstrating the ability of both techniques to preserve the integrity of the separation. While the LODs in “bulk” sampling were lower with ICP-OES, the signal-to-noise values were comparable for both techniques when sampling chromatographic eluents in real-time. In addition, a reversed-phase separation of the same analyte mixture was carried out with Fe I 259.9 nm and S I 180.7 nm optical emission detection by the PB/HC-OES, demonstrating the compatibility of the PB/HC-OES with a wide range of solvent polarities, its ability to detect non-metals and act as a protein specific detector for liquid chromatography of proteins.

A three phase method for detecting optical pulsars

A variant route to lock-in amplifier detection of optical emission from radio pulsars is considered. The method uses the radio pulsar frequency signals as a timing clock but splits the optical signals into equal portions of one third the pulsar period. Differences in their intensities offer evidence for an optical signal at the same frequency as the pulsar without the need to know the phase differences between optical and radio signals. The route benefits from sensitivity to pulsed optical signals seen against a steady background and also allows detection of periodic reductions in intensity. The method is insensitive to changes in observational conditions. When used to acquire star images with the viewing field phase split onto three detector areas, the phase block method should provide intensity differences which identify the location of an optical signal with the frequency of the radio pulsar. Supportive data for the method from a simple laboratory based proof of concept experiment are cited. The three phase block route can equally be applied to searches for polarized emission.

The Anomalous Early Afterglow of GRB 050801

The ROTSE-IIIc telescope at the H.E.S.S. site, Namibia, obtained the earliest detection of optical emission from a Gamma-Ray Burst (GRB), beginning only 21.8 s from the onset of Swift GRB 050801. The optical lightcurve does not fade or brighten significantly over the first ~250 s, after which there is an achromatic break and the lightcurve declines in typical power-law fashion. The Swift/XRT also obtained early observations starting at 69 s after the burst onset. The X-ray lightcurve shows the same features as the optical lightcurve. These correlated variations in the early optical and X-ray emission imply a common origin in space and time. This behavior is difficult to reconcile with the standard models of early afterglow emission.

RAPTOR: Closed‐Loop monitoring of the night sky and the earliest optical detection of GRB 021211

AbstractLaboratory. RAPTOR is a fully autonomous robotic system that is designed to identify and make follow‐up observations of optical transients with durations as short as one minute. The RAPTOR design is based on Biomimicry of Human Vision. The sky monitor is composed of two identical arrays of telescopes, separated by 38 kilometers, which stereoscopically monitor a field of about 1300 square‐degrees for transients. Both monitoring arrays are carried on rapidly slewing mounts and are composed of an ensemble of wide‐field telescopes clustered around a more powerful narrow‐field telescope called the “fovea” telescope. All telescopes are coupled to real‐time analysis pipelines that identify candidate transients and relay the information to a central decision unit that filters the candidates to find real celestial transients and command a response. When a celestial transient is found, the system can point the fovea telescopes to any position on the sky within five seconds and begin follow‐up observations. RAPTOR also responds to Gamma Ray Burst (GRB) alerts generated by GRB monitoring spacecraft. Here we present RAPTOR observations of GRB 021211 that constitute the earliest detection of optical emission from that event and are the second fastest achieved for any GRB. The detection of bright optical emission from GRB021211, a burst with modest gamma‐ray fluence, indicates that prompt optical emission, detectable with small robotic telescopes, is more common than previously thought. Further, the very fast decline of the optical afterglow from GRB 021211 suggests that some so‐called “optically dark” GRBs were not detected only because of the slow response of the follow‐up telescopes. (© 2004 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

MEASUREMENTS OF PLASMA BREAKDOWN

Breakdown is an important process in plasma science but is difficult to study because of its highly transient nature. It depends greatly on the discharge parameters such as geometry, gas pressure and applied voltage. The goal of this research was to study breakdown processes experimentally with sufficiently high spatial and temporal resolution for the features of breakdown to be observed. Measurements of breakdown at low pressure in three different experimental arrangements were made and the results compared. The main measurement method was detection of optical emission. A fluid simulation was used to help interpret results.