Effect of Cumulative Nanosecond Laser Pulses on the Plasma Emission Intensity and Surface Morphology of Pt-and Ag-Ion Deposited Silicon

In this work, the laser induced plasma plume characteristics and surface morphology of Pt- and Ag-ion deposited silicon were studied. The deposited silicon was exposed to cumulative laser pulses. The plasma plume images produced by each laser shot were captured through a computer controlled image capturing system and analyzed with image-J software. The integrated optical emission intensity of both samples showed an increasing trend with increasing pulses. Agion deposited silicon showed higher optical emission intensity as compared to Pt-ion deposited silicon, suggesting that more damage occurred to the silicon by Ag ions, which was confirmed by SRIM/TRIM simulations. The surface morphologies of both samples were examined by optical microscope showing thermal, exfoliational and hydrodynamical sputtering processes along with the re-deposition of the material, debris and heat affected zones＇ formation. The crater of Ption deposited silicon was deeper but had less lateral damage than Agion deposited silicon. The novel results clearly indicated that the ion deposited silicon surface produced incubation centers, which led to more absorption of incident light resulting into a higher emission intensity from the plasma plume and deeper crater formation as compared to pure silicon. The approach can be effectively utilized in the laser induced breakdown spectroscopy technique, which endures poor limits of detection.

Effect of parameters on Si plasma emission in collinear double-pulse laser-induced breakdown spectroscopy

Collinear dual-pulse laser-induced breakdown spectroscopy was carried out on Si crystal by using a pair of nanosecond Nd：YAG laser sources emitting at 1064 nm. The spectral intensities and signal- to-noise ratios of selected Si atomic and ionic lines were used to evaluate the optical emission. The optical emission intensity was recorded while varying the interpulse delay time and energy ratio of the two pulsed lasers. The effects of the data acquisition delay time on the line intensity and signal-to-noise ratio have been investigated as well. Based on the results, the optimal interpulse delay time, energy ratio of the two pulsed lasers, and data acquisition delay time for achieving the maximum atomic and ionic line intensities were found for generation of Si plasma with the collinear dual-pulse laser approach. The dominant mechanism for the observed line intensity variation was also discussed. In addition, the plasma temperature and electron number density at different gate delay times and different interpulse delay times were derived. A significant influence of plasma shielding on the electron temperature and electron number density at shorter interpulse delay times was observed.

The role of microwaves in the enhancement of laser-induced plasma emission

We studied experimentally the effect of microwaves （MWs） on the enhancement of plasma emission achieved by laser-induced breakdown spectroscopy （LIBS）. A laser plasma was generated on a calcium oxide pellet by a Nd：YAG laser （5 m J, 532 nm, 8 ns） in reduced-pressure argon surrounding gas. A MW radiation （400 W） was injected into the laser plasma via a loop antenna placed immediately above the laser plasma to enhance the plasma emission. The results confirmed that when tile electromagnetic field was introduced into the laser plasma region by the MWs, the lifetime of the plasma was extended from 50 to 500 μs, similar to the MW duration. Furthermore, the plasma temperature and electron density increased to approximately 10900 K and 1.5×10^18 cm^-3, respectively and the size of the plasma emission was extended to 15 mm in diameter. As a result, the emission intensity of Ca lines obtained using LIBS with MWs was enhanced by approximately 200 times compared to the case of LIBS without MWs.

The determination of 52 elements in marine geological samples by an inductively coupled plasma optical emission spectrometry and an inductively coupled plasma mass spectrometry with a high-pressure closed digestion method

An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO_3 acid system with a high-pressure closed digestion method（HPCD）, is studied by an inductively coupled plasma optical emission spectrometry（ICP-OES） and an inductively coupled plasma mass spectrometry（ICP-MS）. The operating parameters of the instruments are optimized, and the optimal analytical parameters are determined. The influences of optical spectrum and mass spectrum interferences, digestion methods and acid systems on the analytical results are investigated. The optimal spectral lines and isotopes are chosen, and internal standard element of rhodium is selected to compensate for matrix effects and analytical signals drifting. Compared with the methods of an electric heating plate digestion and a microwave digestion, a high-pressure closed digestion method is optimized with less acid, complete digestion,less damage for digestion process. The marine geological samples are dissolved completely by a HF-HCl-HNO_3 system, the relative error（RE） for the analytical results are all less than 6.0%. The method detection limits are 2–40μg/g by the ICP-OES, and 6–80 ng/g by ICP-MS. The methods are used to determine the marine sediment reference materials（GBW07309, GBW07311, GBW07313）, rock reference materials（GBW07103, GBW07104,GBW07105）, and cobalt-rich crust reference materials（GBW07337, GBW07338, GBW07339）, the obtained analytical results are in agreement with the certified values, and both of the relative standard deviation（RSD） and the relative error（RE） are less than 6.0%. The analytical method meets the requirements for determining 52 elements contents of bulk marine geological samples.

On the green aurora emission of Ar atmospheric pressure plasma

The Ar atmospheric pressure plasma was found to be an excellent laboratorial source for green aurora emission.However,the characteristic and production mechanism of the green aurora emission of the Ar atmospheric pressure plasma are still not clear.In this work,an Ar plasma in a long glass tube which emits intense green aurora light is investigated.With the long glass tube,it can be concluded that the green aurora emission in the Ar plasma is not owing to the mixture of Ar plasma plume with the surrounding air.It is also found that the green aurora emission often appeared beyond the active electrode when the active electrode is placed at the downstream of the gas flow.The green emission disappears when the traces amount of O_(2) or N_(2)(about 0.05%–0.07%)is added to Ar.This is because the O_(2) molecules deactivate the upper state O(^(1)S),which results in the decrease of the green emission.On the other hand,when N_(2) is added,Ar metastable atoms are quenched by N_(2),which results in the decrease of O atoms and eventually leads to the decrease of the green emission intensity.The intensity of the green aurora emission increases when the driving voltage frequency increases from 1 to 10 k Hz.More importantly,it is found that the green aurora emission is not affected when a grounded stainless steel needle is in contact with the plasma plume.Thus,the green emission is not driven electrically.All these findings are helpful for the understanding of the physics and its applications of atmospheric pressure plasma jet in space physics,laser physics and other application areas.

Diagnostic of capacitively coupled radio frequency plasma from electrical discharge characteristics：comparison with optical emission spectroscopy and fluid model simulation

The capacitively coupled radio frequency（CCRF）plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency（RF）discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5？×10^17–3.6？×10^17m^-3.Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.

A Study on the Determination of Copper by Microwave Induced Plasma Atomic Emission Spectrometry (MIP-AES)

The determination of copper by MIP-AES was investigated in detail. Aqueous samples were introduced from an ultrasonic nebulizer and the solvent was removed by a desolvation device before introduction of the aerosol into the MIP. The desolvation system consisted of a condenser associated with a concentrated H2SO4 absorption cell. Various experimental conditions and interferences from easily ionised elements (EIEs) were also studied and some practical samples were analyzed.

CORRECTION OF WING INTERFERENCE WITH KALMAN FILTERING IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROMETRY

A Kalman filter was developed for correction of wing interference in ICP-AES.Modeling wing interference theoretically instead of experimentally, the filter can compensate the shift in wavelength position in scans, and therefore reduce the effect of the interference on detection limit.

Diagnostics of Argon Inductively Coupled Plasma and Dielectric Barrier Discharge Plasma by Optical Emission Spectroscopy

An experimental setup was built up to carry out radio frequency (RF) inductively coupled plasma (ICP) and dielectric barrier discharge (DBD), and to depict the optical emission spectra (OES) of the discharges. OES from argon ICP and DBD plasmas in visible and near ultraviolet region were measured. For argon ICP, the higher RF power input (higher than 500 W for our machine), the higher degree of argon plasma ionization. But that doesn't mean a higher mean electron energy. With the increase in the power input, the mean electron energy increases slightly, whereas the density of electron increases apparently On the contrary, argon DBD discharge behaves in the manner of a pulsed DC discharge on optical emission spectroscopy and V-I characteristics. DBD current is composed of a series of pulses equally spaced in temporal domain. The Kinetics of DBD emission strength is mainly governed by the frequency of the current pulse.

Determination of potassium content as principal components in pyrotechnic compositions used for fireworks and firecrackers based on inductively coupled plasma optical emission spectrometric approach （ICP-OES）

Inductively coupled plasma optical emission spectrometric approach（1CP-OES） is used to determine the potassium content as principal component in pyrotechnic compositions used for fireworks and firecrackers. Element of potassium is conunonly found in potassium nitrate and potassium perchlorate in pyrotechnic compositions in fireworks and firecrackers. Statistical analysis shows that potassium nitrate content in pyrotechnics is between 10% to 60% and the potassium perchlorate content is between 20% to 70%,which counted in the content of potassium element is between 4% to 23%. Concept of this method： considering the weight of the sample is 400rag,constant volume is 1L and the concentration of potassium is between 10 mg/L to 90 mg/L in sample solution, the determination scope of the method for the potassium content would be between 1% to 23%.Further experiments proved that the fitting correlation coefficient of potassium calibration curve is 0.9997 or higher, recovery is 89.15%-100.23%.The allowable differential value is 0.4% between two single tests under repeatable conditions. This method can completely satisfy the requirements of the fireworks and firecrackers industry with high accuracy and good precision.

Determination of magnesium and aluminum content as principal components in pyrotechnic compositions used for fireworks and firecrackers based on inductively coupled plasma optical emission spectrometric approach （ICP-OES）

Inductively coupled plasma optical emission spectrometric approach（ICP-OES）is used to determine the magnesium and aluminum content as principal components in pyrotechnic compositions used for fireworks and firecrackers. Elements of magnesium and aluminum are commonly found in aluminum powder or magnesium-aluminum alloy powder in pyrotechnic compositions in fireworks and firecrackers. Statistical analysis shows that the magnesium content in pyrotechnics is between 8% to 30% and the aluminum content is between 8% to 35%（roughly）.Concept of this method： suppose the weight of the sample is 400rag,constant volume is IL and the concentlation of magnesium and aluminum is between 12mg/L to 160mg/L in sample solution, the determination scope of the method for magnesium and aluminum content would be between 3% to 40%.Further experiments proved that the fitting correlation coefficient of the magnesium calibration curve is 0.9999 or higher, recovery is 101.01% -101.96%.The fitting correlation coefficient of the aluminum calibration curve is 0.9999 or higher, recovery is 99.36%-103.07%. The allowable differential value is 0.4% between two single tests under repeatable conditions. This method can completely satisfy the requirements of the fireworks and firecrackers industry with high accuracy and good precision.

Steady and oscillatory plasma properties in the near-field plume of a hollow cathode

Hollow cathodes serve as electron sources in Hall thrusters,ion thrusters and other electric propulsion systems.One of the vital problems in their application is the cathode erosion.However,the basic erosion mechanism and the source of high-energy ions cause of erosion are not fully understood.In this paper,both potential measurements and simulation analyses were performed to explain the formation of high-energy ions.A high-speed camera,a single Langmuir probe and a floating emissive probe were used to determine the steady and oscillatory plasma properties in the near-field plume of a hollow cathode.The temporal structure,electron temperature,electron density,and both static and oscillation of plasma potentials of the plume have been obtained by the diagnostics mentioned above.The experimental results show that there exists a potential hill（about 30 V） and also severe potential oscillations in the near-plume region.Moreover,a simple 2 D particle-in-cell model was used to analyze the energy transition between the potential hill and/or its oscillations and the ions.The simulation results show that the energy of ions gained from the static potential background is about 20 e V,but it could reach to 60 e V when the plasma oscillates.

Compound Ceramic Coatings Grown by Micro-plasma Oxidation on Ti-6Al-4V Alloy

Compound ceramics coatings on the Ti-6Al-4V alloy were prepared by the direct current micro-plasma oxidation （MPO） in NaAlO2 solution. The composition and morphology of the coatings were studied with the X-ray diffraction （XRD） and the scanning electron microscopy （SEM）, respectively. Inductively coupled plasma atomic emission spectrometer technique was used to analyze the solution features of Ti-6Al-4V alloy in the process of preparation. The results reveal that Al2TiO5 forms in the coatings at the initial stages of MPO reaction, and its content changes rapidly with the reaction continuing： after 20 min, the ceramics coatings are composed of α-Al2O3, 7-Al2O3 and Al2TiO5, but after 40 min, its main composition is of α-Al2O3. The content of Ti in the solution will increase when the MPO time extends, and as will Al in the anode area until, after 30 min, it reaches the maximum and keeps constant from then on. Both substrata of Ti and Al in the electrolyte join the MPO reaction at the initial stage, where the formation of Al2TiO5 happens; but as the MPO reaction prolongs, more and more Al in the electrolyte will take part in the reaction, leading to the appearance of a large amount ofAl2O3.

Understanding hydrogen plasma processes based on the diagnostic results of 2.45 GHz ECRIS at Peking University

Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.

Structural and mechanical properties of Al–C–N films deposited at room temperature by plasma focus device

The Al–C–N films are deposited on Si substrates by using a dense plasma focus（DPF） device with aluminum fitted central electrode（anode） and by operating the device with CH_4/N_2 gas admixture ratio of 1：1. XRD results verify the crystalline Al N（111） and Al_3CON（110） phase formation of the films deposited using multiple shots. The elemental compositions as well as chemical states of the deposited Al–C–N films are studied using XPS analysis, which affirm Al–N, C–C, and C–N bonding. The FESEM analysis reveals that the deposited films are composed of nanoparticles and nanoparticle agglomerates. The size of the agglomerates increases at a higher number of focus deposition shots for multiple shot depositions. Nanoindentation results reveal the variation in mechanical properties（nanohardness and elastic modulus）of Al–C–N films deposited with multiple shots. The highest values of nanohardness and elastic modulus are found to be about 11 and 185 GPa, respectively, for the film deposited with 30 focus deposition shots. The mechanical properties of the films deposited using multiple shots are related to the Al content and C–N bonding.

OH and O radicals production in atmospheric pressure air/Ar/H_2O gliding arc discharge plasma jet

Atmospheric pressure air/Ar/H_2O gliding arc discharge plasma is produced by a pulsed dc power supply. An optical emission spectroscopic（OES） diagnostic technique is used for the characterization of plasmas and for identifications of OH and O radicals along with other species in the plasmas. The OES diagnostic technique reveals the excitation Tx？≈？5550–9000 K, rotational Tr？≈？1350–2700 K and gas Tg？≈？850–1600 K temperatures, and electron density n？（1.1-1.9） ′101 4 cm^（-3） e under different experimental conditions. The production and destruction of OH and O radicals are investigated as functions of applied voltage and air flow rate. Relative intensities of OH and O radicals indicate that their production rates are increased with increasing Ar content in the gas mixture and applied voltage. nereveals that the higher densities of OH and O radicals are produced in the discharge due to more effective electron impact dissociation of H_2O and O_2 molecules caused by higher kinetic energies as gained by electrons from the enhanced electric field as well as by enhanced n e.The productions of OH and O are decreasing with increasing air flow rate due to removal of Joule heat from the discharge region but enhanced air flow rate significantly modifies discharge maintenance properties. Besides, Tgsignificantly reduces with the enhanced air flow rate. This investigation reveals that Ar plays a significant role in the production of OH and O radicals.

Tomography of a simply magnetized toroidal plasma

Optical emission spectroscopy is a passive diagnostic technique,which does not perturb the plasma state.In particular,in a hydrogen plasma,Balmer-alpha（Hα） emission can be easily measured in the visible range along a line of sight from outside the plasma vessel.Other emission lines in the visible spectral range from hydrogen atoms and molecules can be exploited too,in order to gather complementary pieces of information on the plasma state.Tomography allows us to capture bi-dimensional structures.We propose to adopt an emission spectroscopy tomography for studying the transverse profiles of magnetized plasmas when Abel inversion is not exploitable.An experimental campaign was carried out at the Thorello device,a simple magnetized torus.The characteristics of the profile extraction method,which we implemented for this purpose are discussed,together with a few results concerning the plasma profiles in a simply magnetized torus configuration.

Application and Development Trends of Spectral Analysis in Draft of Non-Ferrous Metal Standards in China

Spectral analysis was a method of identifying substances, determining their chemical composition and calculating their content based on their spectral characteristics. This paper mainly discussed the application of various spectroscopic techniques, mainly including atomic absorption spectrometry (AAS) inductively coupled plasma emission spectrometry (ICP-AES) X-ray fluorescence spectroscopy (XRF) atomic fluorescence spectroscopy (AFS) direct reading spectroscopy (OES) glow discharge emission spectroscopy (GD-OSE) laser-induced breakdown spectroscopy (LIBS), in the formulation of non-ferrous metal standards in China. The AAS method was the most widely used single-element microanalysis method among the non-ferrous metal standards. The ICP-AES method was good at significant advantages in the simultaneous detection of multiple elements. The XRF method was increasingly used in the determination of primary and secondary trace elements due to its simple sample preparation and high efficiency. The AFS was mostly detected by single-element trace analysis. OES GD-OES and LIBS were playing an increasingly important role in the new demand area for non-ferrous metals. This paper discussed matrix elimination, sample digestion, sample preparation, instrument categories and other aspects of some standards, and summarized the advantages of spectral analysis and traditional chemical analysis methods. The new methods of future spectroscopic technology had been illustrated in the process of developing non-ferrous metal standards.

Effects of Different Pretreatment Methods on Determination of Microelements in Feed

[ Objective] To study the effects of different pretreatment methods on determination of microelement in feed and thus find the best pre treatment method for each microetement, t Method] The samples （concentrated feeding stuff and fodder） were pretreated through throe methods, that is, dry incineration method, HNOs HCIO, wetdecomposition method and microwave digestion method. Then the content of seven kinds of mi croelement （AI, Ca, Cu, Fe, Mn, Se and Zn） was determined by inductively coupled plasma atomic emission spectrometer （ICPAES）. I Result] These three methods were all suitable for the determination of Cu, Mn and Zn in concentrated feeding stuff and the determination of Cu and Ca in fodder. The content of Cu and Ca was higher in fodder detected by HNO3 HCIO, wetdecomposition method. The microwave digestion method was suitable for the determination of AI and Ca in concentrated feeding stuff and the determination of AI, Fe, Mn and Zn in fodder. The dry incinera tion method was fit for the determination of Fe in concentrated feeding stuff. [ Condusionl The content of different microelements should be deter mined after the feed is treated with different Ioretreatment methods.

Determination of wholesome elements and heavy metals in safflower(Carthamus tinctorius L.)from Xinjiang and Henan by ICP-MS/ICP-AES

An inductively coupled plasma mass spectrometry （ICP-MS） or inductively coupled plasma atomic emission spectrometry （ICP-AES） was developed to determine 19 elements in safflower, a traditional Chinese medicinal herb from Xinjiang Autonomous Region and Henan Province of China. Totally 19 elements in safflower included heavy metals, i.e. As, Cd, Cu, Hg and Pb, and wholesome elements, i.e. Al, Ca, Co, Cr, Fe, Mg, Mn, Mo, Ni, P, Se, Sr, V and Zn. The results showed that the concentrations of heavy metals in safflower samples were both low, all of which met the national hygiene standards except for Pb in Xinjiang sample. Meanwhile, the distribution tendency of elements in the two samples was similar, which indicated that the plant might absorb given elements in a proportional way. The method can be used for the quality control of elements in safflower, and it provides a way for the determination of the contents of safflower from Xinjiang and Henan.