Characteristic Spectral Lines Research Articles

A Be-type star with a black-hole companion

Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars (stars of the Be type are hot blue irregular variables showing characteristic spectral emission lines of hydrogen). Of the approximately 80 Be X-ray binaries known in the Galaxy, however, only pulsating neutron stars have been found as companions. A black hole was formally allowed as a solution for the companion to the Be star MWC 656 (ref. 5; also known as HD 215227), although that conclusion was based on a single radial velocity curve of the Be star, a mistaken spectral classification and rough estimates of the inclination angle. Here we report observations of an accretion disk line mirroring the orbit of MWC 656. This, together with an improved radial velocity curve of the Be star through fitting sharp Fe II profiles from the equatorial disk, and a refined Be classification (to that of a B1.5-B2 III star), indicates that a black hole of 3.8 to 6.9 solar masses orbits MWC 656, the candidate counterpart of the γ-ray source AGL J2241+4454 (refs 5, 6). The black hole is X-ray quiescent and fed by a radiatively inefficient accretion flow giving a luminosity less than 1.6 × 10(-7) times the Eddington luminosity. This implies that Be binaries with black-hole companions are difficult to detect in conventional X-ray surveys.

土壤中砷元素的激光诱导击穿光谱测量分析

This paper analyzed the characteristics of laser-induced breakdown spectroscopy (LIBS) of metal element arsenic in soil using the Nd:YAG (wavelength: 1064 nm) laser as the excitation source, where the spectral signals were detected by the high resolved, wide spectral ECHELLE spectrograph and intensity charged coupled device (ICCD). The time evolution of the characteristic spectral line of arsenic was obtained by changing the delay time of ICCD at the same concentration and the gate of ICCD with wavelength of 228.8 nm of arsenic as the characteristic spectral line, from which a best delay time of 1 s and a gate width of 2 s were found. By measuring the intensities of the characteristic spectral line with different arsenic concentrations, it was demonstrated that the intensities of the spectral line increased with the concentration of arsenic under the condition of low concentration. From the results, the LIBS calibration curve of arsenic was obtained, and the detection limit of arsenic in soil at 45 mg/kg was obtained.

Black hole found orbiting a fast rotator

Stars of spectral type 'Be' are often found with neutron stars or other evolved analogues, but a black-hole companion has never been spotted before. Optical emission from a black hole's surroundings has given it away. See Letter p.378 Binary evolution models predict the existence of black holes accreting from the equatorial envelope of rapidly spinning 'B-emission' or 'Be' stars — young, blue irregular variables that show the characteristic spectral emission lines of hydrogen. So far, however, most of the compact stellar companions found in Be X-ray binaries have been identified as neutron stars. A few contain subdwarf stars but until now none had been found to host a black hole. The picture changes with the discovery of an unprecedented He II 4,686 A optical emission line in the spectrum of an accretion disk around the companion to the Be star MWC 656. This, together with other information, points to the presence a black hole of 3.8 to 6.9 solar masses.

Qualitative tissue differentiation by analysing the intensity ratios of atomic emission lines using laser induced breakdown spectroscopy (LIBS): prospects for a feedback mechanism for surgical laser systems

The research work presented in this paper focuses on qualitative tissue differentiation by monitoring the intensity ratios of atomic emissions using ‘Laser Induced Breakdown Spectroscopy’ (LIBS) on the plasma plume created during laser tissue ablation. The background of this study is to establish a real time feedback control mechanism for clinical laser surgery systems during the laser ablation process. Ex-vivo domestic pig tissue samples (muscle, fat, nerve and skin) were used in this experiment. Atomic emission intensity ratios were analyzed to find a characteristic spectral line for each tissue. The results showed characteristic elemental emission intensity ratios for the respective tissues. The spectral lines and intensity ratios of these specific elements varied among the different tissue types. The main goal of this study is to qualitatively and precisely identify different tissue types for tissue specific laser surgery. (© 2013 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

Spectral Characterization of Nitrogen in Farmland Soil by Laser-Induced Breakdown Spectroscopy

ABSTRACT Nitrogen is one of the most important elements in farmland soil, and nitrogen content is one of the evaluation indicators of fertilizers. It is difficult to measure the nitrogen content in farmland soil because the chemical and physical properties of farmland soil are complex. Through the adoption of buffer gases to remove the influence of the nitrogen in air, this paper studied the laser-induced breakdown spectroscopy (LIBS) characteristics of nitrogen in soil to establish a foundation for in situ measurement of nitrogen in farmland soil. Three characteristic spectral lines have been found. Based on the precise controlling of laser power and triggering of delay time between laser generation and spectra collection, we have studied the effects of laser energy on LIBS spectral characteristics and the time evolution characteristics to supply the basis of parameter optimization for the measurement. In addition, we have studied the relationship between nitrogen concentration and LIBS spectral intensity. The results demonstrated that LIBS was an effective measurement method of nitrogen content in farmland soil with simple hardware structure, fast detection, and high precision.

Assessment of feasibility in determining of Cr in Gannan Navel Orange treated in controlled conditions by laser induced breakdown spectroscopy

Heavy metal element chromium (Cr) contained in Gannan Navel Orange fruits treated with contaminant in controlled lab conditions were analyzed by laser induced breakdown spectroscopy (LIBS) and atomic absorption spectrometry (AAS). The purpose of this work was to provide an assessment of the performance of LIBS in investigating heavy metals in natural organic materials through a direct comparison of the analytical results. The LIBS spectra of samples were collected by optimized experimental parameters and the characteristic spectral lines of two triplet bands at 357.87nm, 359.35nm and 360.53nm and 425.43nm, 427.48nm and 428.97nm were identified distinctly. The Cr I 425.43nm was selected as analytical line. The concentrations of Cr element were determined by AAS. The relative standard deviation (RSD) values were analyzed and the results demonstrated that there are much more room to promote in LIBS measuring. The calibration curve between the LIBS intensity and AAS concentration was constructed about Cr element. The results show LIBS signal intensity linear dependence on the concentration of Cr. Quantitative analytical results by the curve were validated with AAS measurements. The presented results showed that the standard deviations of the LIBS measurements are in general much larger than those of AAS measurements. Mostly, this contributes to matrix effect of samples and instability of LIBS. In a word, the obtained results between LIBS and AAS demonstrate the capacity of LIBS in the determination of the concentrations of Cr in oranges. Further work are being continued in our laboratory for further improvement of the sensitivity of LIBS, and for direct analysis of heavy metals in natural agricultural products without contamination treatment.

Comparison of Calibration Curve Method and Partial Least Square Method in the Laser Induced Breakdown Spectroscopy Quantitative Analysis

The Laser Induced Breakdown Spectroscopy (LIBS) is a fast, non-contact, no sample preparation analytic technology; it is very suitable for on-line analysis of alloy composition. In the copper smelting industry, analysis and control of the copper alloy concentration affect the quality of the products greatly, so LIBS is an efficient quantitative analysis technology in the copper smelting industry. But for the lead brass, the components of Pb, Al and Ni elements are very low and the atomic emission lines are easily submerged under copper complex characteristic spectral lines because of the matrix effects. So it is difficult to get the online quantitative result of these important elements. In this paper, both the partial least squares (PLS) method and the calibration curve (CC) method are used to quantitatively analyze the laser induced breakdown spectroscopy data which is obtained from the standard lead brass alloy samples. Both the major and trace elements were quantitatively analyzed. By comparing the two results of the different calibration method, some useful results were obtained: both for major and trace elements, the PLS method was better than the CC method in quantitative analysis. And the regression coefficient of PLS method is compared with the original spectral data with background interference to explain the advantage of the PLS method in the LIBS quantitative analysis. Results proved that the PLS method used in laser induced breakdown spectroscopy was suitable for simultaneous quantitative analysis of different content elements in copper smelting industry.

Spectral Analysis of Laser Processing of Carbon Fiber Reinforced Plastics

Spectra of the optical process emissions of carbon fiber reinforced plastics (CFRP) processing with a continuous wave (cw) thin disk laser are recorded for a basic characterization of the ablation process. The observed line spectra show a characteristic spectral line at a wavelength of 588.95 nm that is found to be atomic sodium (Na I). No spectral lines of atomic or ionized carbon appear in the recorded spectra leading to the conclusion that only a small fraction of C-atoms is ionized.

Experimental Study of Current-Voltage Characteristics and Optical Emission of Various Gases in Dielectric Barrier Discharge at Atmospheric Pressure

Abstract This study reports experimental investigations of current-voltage characteristics and optical emission from argon, helium, nitrogen, and air plasma generated by 17-kHz dielectric barrier discharge at atmospheric pressure. The plasma reactor is custommade with (i) an electrode diameter of 9.6 cm and gap between electrodes of 0.3 cm (ii) dielectric materials of 4.8 in dielectric constant and 0.2 cm in thickness. The plasma reactor has been modeled as a capacitance from dielectric barriers in series with a capacitance from working gas in parallel to variable impedance from the discharging plasma. External 50-Ω resistor and 0.1-μF capacitor were coupled to the reactor for measuring total current and total charge transfer, respectively. The discharge current is obtained from subtracting the measured current with the stray-capacitive and the gaseous-capacitive current. The charge over the external 0.1-μF capacitor and the applied voltage were used to plot Lissajous figures. From such a figure, it is observed that helium starts the first discharge of a few μs in its characteristic time at 2 kVp-p, then the second discharge of a few ten μs at 4 kVpp. The former discharge is understood as glow-like discharge while the latter discharge as Townsend-like one. In 2-6 kVp-p range, four discharge peaks were observed in total. Argon has their first discharge at higher voltage of about 5 kVp-p. Nitrogen and air plasma were much more difficult to discharge. They do not glow in the voltage range of up to 17 kVp-p but rather show filamentary discharge instead. The optical emission confirms the characteristic spectral lines of each gas; however, it could not differentiate the glow-like discharge from the Townsend-like one.

紫铜等离子体特征谱线及其展宽形成机制

A series of plasma characteristic spectral lines of red copper were obtained under nanosecond laser shock with a pulsed Nd:YAG laser (1064 nm， maximum energy 500 mJ). It can be inferred from the experimental result that the copper atomic spectrum is incomplete, only five distinct excitation spectral lines (CuⅠ 406.33 nm, CuⅠ 458.69 nm, CuⅠ 521.8 nm, CuⅠ 529.25 nm, CuⅠ 578.2 nm) are found in our experimental condition. The line shapes of broadening of CuⅠ 521.8 nm and CuⅠ 578.2 nm atomic spectral lines are different, and belong to Lorenz and Gauss line shapes, respectively. The analysis of corresponding equations of line shapes shows that different bands in the same atomic spectrum correspond to different spectral broadening mechanisms.

Analysis of TIG Arc Spatial Radiation Based on Scanning Method

The article collected radiation intensity of TIG arc plasma in different dimensions and analyzed arc spectrum by establishing horizontal scanning system of plasma. Choose Fe and Ar characteristic spectral line as the subjects; acquire the distribution of arc radiation in different dimensions through Abel conversion; calculate temperature of plasma using Boltzmann. The results indicated that the position of strongest radiation is about 1mm from the tungsten pole, then it gradually weakens along the radial direction and the gradient of Ar spectral line is greater. The lowest temperature is near the base metal and the highest one is near tungsten pole.

Microwave Initiated Atomic Spectra from Select Atomic Species

Isotopes of gaseous Helium (3He and 4He) were admitted into the vacuum system at various pressures and allowed to stabilize. Quantum states were then energized using a 2.45 GHz magnetron coupled to the gases by loose coupling. A residual gas analyzer Model 100 series manufactured by Stanford Research Systems was used to determine the mass of each species.An Ocean Optics Optical Spectrometer model collecting the light via an optic probe was used to obtain the spectra and to characterize the spectroscopic peaks. The data collected from these isotopes represent characteristic spectral emission lines generated due to the transitions among discrete quantum energy levels.The data analysis, especially for atomic spectroscopy, becomes an extremely important tool in developing an understanding of the quantum levels active within each atom. In this paper is presented a summary of the analysis of work that was done on two isotopes of helium. Data using both computational as well as theoretical techniques are presented. Traditional high voltage arc discharge data were taken for the gas species and these are compared with microwave stimulated atomic emissions.

Identification of Irradiated Cashew Nut by Electron Paramagnetic Resonance Spectroscopy

Cashew nut samples were irradiated at gamma-radiation doses of 0.25, 0.5, 0.75, and 1 kGy, the permissible dose range for insect disinfestation of food commodities. A weak and short-lived triplet (g = 2.004 and hfcc = 30 G) along with an anisotropic signal (g perpendicular = 2.0069 and g parallel = 2.000) were produced immediately after irradiation. These signals were assigned to that of cellulose and CO 2 (-) radicals. However, the irradiated samples showed a dose-dependent increase of the central line (g = 2.0045 +/- 0.0002). The nature of the free radicals formed during conventional processing such as thermal treatment was investigated and showed an increase in intensity of the central line (g = 2.0045) similar to that of irradiation. Characteristics of the free radicals were studied by their relaxation and thermal behaviors. The present work explores the possibility to identify irradiated cashew nuts from nonirradiated ones by the thermal behaviors of the radicals beyond the period, when the characteristic electron paramagnetic resonance spectral lines of the cellulose free radicals have essentially disappeared. In addition, this study for the first time reports that relaxation behavior of the radicals could be a useful tool to distinguish between roasted and irradiated cashew nuts.

Identification of different type of polymers in plastics waste

The main goal of this work was to develop and test advanced techniques for the instant identification of different type of polymers in post-consumer plastics. In order to accomplish this task, infrared (IR), X-ray diffraction (XRD), differential scanning calorimetric (DSC) and laser induced breakdown spectroscopic (LIBS) techniques were applied. The following six model plastics were identified in this study. Low-density polyethylene (LDPE), High-density polyethylene (HDPE), Polypropylenes (PP), Polystyrene (PS), Polyethylene terephthalate (PET) and Polyvinyl chloride (PVC) along with few randomly selected plastics waste such as water bottle and cap, water cups, yogurt container and coke bottle were studied. IR has shown the fingerprinting of polymer types present in plastics waste. The XRD analysis helps to provide characteristic spectral lines whose intensities vary with the type of each constituent polymer. The DSC method provided the different crystalline melting temperature, glass transition, and onset temperature for the peaks and the percent crystallinity data single out different polymers. The ratio of LIBS signals intensities of carbon and hydrogen atoms were employed for the finger printing of the different family of plastics. The combined use of IR, XRD, DSC and LIBS techniques yielded very useful and effective results for plastic waste management.

The coulomb potential energy effect on the intensity of the characteristic lines at highly charged ion incendence on Al surface

The Al atomic characteristic spectral lines were induced by the impact of 40Arq+ ions (8≤q≤16; kinetic energy 150keV) on Al surface. The result shows that by Penning impinging and resonant capture, the ion energy is deposited on the Al surface to excite the target atom, which is different from light excitation. Not only are the transitions betweem electronic configurations of the atomic complex excited, but the enhancing tendency of the characteristic spectral line intensity is consistent with the enhancing tendency of the coulomb potential energy of the incident ions with increasing charged states.

Terahertz time-frequency analysis with Gabor wavelet-transform

We applied different shaping factors of Gabor wavelet for the analysis of terahertz time-domain spectroscopy with wavelet_transform. Gabor wavelet analysis allows a convenient switching between time domain and frequency domain by varying shaping factors. The comparison of absorption spectral lines obtained between with wavelet-transform and with other methods demonstrated that wavelet-transform is a reliable technique for the analysis of the absorption properties and the extraction of the characteristic spectral lines in terahertz range.

Recent advances in piezospectroscopy

Abstract Strain produces small but systematic changes in the Raman and luminescence spectra of solids. Piezospectroscopy is a technique that exploits these changes for determining stresses, usually from shifts in a characteristic spectral line. In this review in honor of Wolfgang Pompe, recent advances in piezospectroscopy applied to the determination of stresses in alumina materials are described.

Characteristic frequency of the magnetic radiation of spinor condensates

The magnetic radiation of the fully condensed states of spinor condensates has been studied. A narrow characteristic spectral line together with a strong background at its violet side have been found. For the condensate of $N={10}^{12}$ atoms of $^{23}\mathrm{Na}$ confined in an isotropic and harmonic trap with frequency ${\ensuremath{\omega}}_{o}=300\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, for instance, the photon energy of the characteristic line is $127.9\ensuremath{\hbar}{\ensuremath{\omega}}_{o}$ with width $<1.\ensuremath{\hbar}{\ensuremath{\omega}}_{o}$ and the probability of transition is $1.44\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}34}\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$. The photon energy and probability have been found to be proportional to ${N}^{2∕5}$ and ${N}^{17∕5}$, respectively. It implies that magnetic radiations with higher photon energies and much larger probabilities can be obtained if numerous atoms are trapped. A technique developed by the authors, namely, the analytical forms of the fractional parentage coefficients, was used to calculate analytically the matrix elements between the spin states that conserve the total spin and its $Z$ component.

Integrated Mach-Zehnder micro-interferometer on LiNbO 3

This work presents a scanning micro-interferometer, without moving parts, based on the well-known Mach-Zehnder geometry. The micro-system was obtained by using non-standard processes of planar technology on lithium niobate crystals, in particular the waveguide fabrication was obtained by using high energy ion implantation of medium light mass elements. The scanning effect without moving parts has been obtained by changing the refractive index of the optical waveguides by using electric field. The whole device is 60 mm long with a 0.5×1 mm 2 cross section, weights only few grams and its power consumption lies in the milliwatt range. The performances were preliminary tested in the spectral window ranging from 0.4 to 1.0 μm. By using standard radiation sources, this micro-system demonstrated a spectral resolution suitable for detecting the characteristic spectral lines of a Xe-arc lamp on a 400 nm wide spectral window. In a further experiment we tested the performances of the microinterferometer for gas trace detection by using a calibrated NO 2 optical gas cell. A sensitivity of about 10 ppb for NO 2 detection, when suitable optical paths are used, was evaluated.

Action spectrum for healing of psoriasis

To the Editor, In their recent review on the mechanisms of ultraviolet B (UVB) phototherapy, Weichenthal and Schwarz (1) comment that radiation in the spectral range between 311 and 313 nm clears psoriasis better than other wavelengths. Similar statements appear not infrequently in publications concerning TL-01 narrowband lamps. We suggest that the limited experimental data on wavelength dependence of psoriasis clearance has been over-interpreted and that the reason for arriving at this conclusion has more to do with physics than biology. In their early studies of the UV wavelengths effective in clearing psoriasis, Fischer and colleagues (2–4) examined the efficacy of discrete wavelengths from 254 to 405 nm. They demonstrated that a wavelength of 313 nm was effective for psoriasis clearance, particularly at higher doses. However, other UVB and UVC wavelengths between 254 and 313 nm were not studied and therefore these data have only limited clinical relevance. Furthermore the reason for the choice of wavelengths studied (254, 313, 334, 365 and 405 nm) was that they are all characteristic spectral lines emitted by the mercury arc lamps that were used by these investigators. Parrish and Jaenicke (5) studied the response of psoriasis to different wavelengths (254, 280, 290, 296, 300, 304 and 313 nm), by irradiating small areas of lesional skin on a daily basis, using various multiples of the minimal erythema dose (MED). No clearance of psoriasis was found with wavelengths of 290 nm or less. Clearance was achieved at wavelengths of 296– 313 nm, with some suggestion of a better response at 313 nm. However, only four patients were studied, and they were found to have relatively treatment-resistant psoriasis. Furthermore, as would be expected with such a small sample size, when we applied analysis of variance to the authors’ data, we found no significant difference between the four different UVB wavelengths (296, 300, 304 and 313 nm) in terms of lowest effective daily dose (LEDD) relative to the MED to clear psoriasis (P5 0.20), the number of treatments needed to clear with the LEDD (P5 0.45), or the lowest number of treatments to clear (P5 0.47). So while phototherapy using narrowband (311 nm) UVB fluorescent lamps proves to be an effective treatment for psoriasis (6), we should remain cautious about attributing this particular wavelength of the UVB spectrum with special healing properties.