Optical Multichannel Analyzer System Research Articles

Preliminary spectral investigation on Betel Nut (“Pinang”) using Laser Induced Breakdown Spectroscopy (LIBS)

Preliminary optical spectroscopy studies have been carried out on betel nut samples using a new analytical tool, LIBS. The LIBS system consists of an neodymium -doped yttrium aluminium garnet (Nd YAG) laser as an excitation source, laser beam conditioning equipment, and an optical multichannel analyzer system (OMA system). Betel nut samples were collected from Aceh, Indonesia. The experiment was carried out under ambient air with a pressure of 760 Torr. It was found that strong luminous plasma could be generated directly from fresh betel nut samples, which resulted in strong emission spectrum. The emission spectrum obtained should have been dominated by host organic matter (C-H-O-N), but not as imagined because the organic host elements did not appear predominantly in the spectrum. Different treatments need to be carried out in further research so that the host organic matter appears. However, some salts, namely Mg, Fe, Na, Ca, Si, Al and K can be detected clearly. These initial investigations hold the promise of LIBS for spectral studies of betel nuts.

Preliminary evaluation of chemical component in the 2004 indian ocean giant tsunami impacted soil using a Co2 Laser Induced Breakdown Spectroscopy (LIBS)

Preliminary evaluation of chemical component in soil impacted by 2004 Indian Ocean giant tsunami using LIBS has been carried out. The sampling of the tsunami impacted soil was carried out in several points in Aceh, Indonesia. In this study, the sample soil was pretreated to turn into pellets. The beam of a TEA CO2 laser (10.6 µm, 3 J, 200 ns, 10 Hz) is sent onto surface of pellet using focusing lens under air at atmospheric pressure for producing a plasma. The emission spectral lines from plasma that generated were discovered when testing with Optical Multichannel Analyzer (OMA) system. It shows many emission lines because of various elements could clearly be detected and be identified. It was found that both the tsunami impacted and unimpacted soil sample contain chemical signatures of tsunami event such as saltwater signal (Na), carbonate markers (Ca, Mg, Sr), terestrial markers (Fe, Mn, Si Ti, Ba), and other heavy metal elements. However, it is found that emission intensities of the spectral lines are far higher for the tsunami impacted soil samples compared to the case of tsunami unimpacted soil. The qualitative observation finding implies that the chemical elements such as calcium (Ca), then followed by magnesium (Mg), and sodium (Na) are good candidate for chemical proxies of tsunami event. Since the measurement allows to simultaneously observe these elements in a single measurement, thus LIBS is a potential, simultaneous, efficient, and versatile spectroscopic technique not only for analyzing chemical component in soil affected by the tsunami but also to identify the tsunami impacted soil from the impacted soilThe first section in your paper.

New approach allowing detection of Cl using a pulsedcarbon dioxide (CO2) laser-induced breakdown spectroscopy (LIBS)

A new approach to allow detection of Cl emission using atransversely excited atmosphere (TEA) carbon dioxide (CO2) laser-induced breakdown spectroscopy (LIBS), namely utilization of a metal sub-target, was introduced. The Cl sample was prepared from pure chemical powder in the form of a solutiondeposited on the metal sub-target. A zinc selenium lens was used to focus the CO2 laser beam (10.6Mm, 2.5 J, 10 Hz, 200 ns) onto the deposited sample under the surrounding gas of helium (pressure of 1 atm) for generated luminous plasma. An optical multichannel analyzer (OMA) system was used for collecting plasma and acquiring the emission spectrum. It was found that luminous plasma can be produced upon focusing the laser irradiation onto the deposited layer of the sample on the subtarget metal while leaving no ablation from the sub-target metal. Many ionic emission lines from Cl can be detected in the visible region.The ionic emission lines occur withfavorable spectrochemical features, namely strong emission intensity and low background level. Thus, this new approach is promising for conducting Cl analysis using a CO2 LIBS.

Characteristics of laser induced breakdown investigated by a compact, nongated optical multichannel analyzer system and its potential application

Laser induced breakdown is a highly temporally and spatially dynamic phenomenon, normally studied using a highly temporally resolved optical detector system. In this work, a compact, low cost optical multichannel analyzer (OMA) system without a built-in temporal gating device and thus operated under a free running mode was used to investigate the characteristics of laser induced plasma. A Nd-YAG laser beam was used as the excitation source from several samples, namely, copper, zinc, and aluminum plates. The characteristics of the plasma emission produced under various experimental parameters, including the pulse energy, surrounding gas pressure, and collection fiber position, were examined. It was found that the essential features of emission spectra can be investigated even using the ungated, compact OMA system even without a highly temporally resolved gating system. The plasma emission characteristics critically depend on the experimental parameters. A quality emission spectrum, featuring a high intensity with a low background, can be obtained using the ungated, compact OMA system under optimized conditions, namely, a pulse energy of approximately 8 mJ, a surrounding gas pressure of 10 Torr, and a collection fiber position of more than 5 mm above the surface of the sample. The features of the emission spectra detected under optimized conditions are only similar to those obtained using a sophisticated, gated OMA system. The characteristics of the emission spectra are in good agreement with the previous assumption of the shockwave role in plasma excitation. Having quality emission spectra under the optimized conditions, a preliminary practical laser induced breakdown spectroscopy (LIBS) analysis using the ungated, compact OMA system was performed on several samples, such as standard brass, commercial pure gold, and natural stone samples. The aluminum emission lines are strongly detected from the standard brass sample (C1118) containing aluminum at 2.8%. The LIBS system also unequivocally revealed a qualitatively abandoned impurity presence in the purportedly pure commercial gold sample. It also effectively confirmed qualitatively a Cu presence in the blinking spots of the natural stone collected from a traditional mining site in Aceh. This result implies the effectiveness of the LIBS using the ungated, compact OMA system for quick, practical analysis.

Analysis of asymmetry of the D α emission spectra under the Zeeman effect in boundary region for D–D experiment on EAST tokamak* *Project supported by the National Natural Science Foundation of China (Grant No. 11805234).

In 2015 campaign, deuterium atomic emission spectra (D α ) under the Zeeman effect in boundary region had been measured by a high resolution optical spectroscopic multichannel analysis (OSMA) system based on passive spectroscopy during the deuterium plasma discharge on EAST tokamak, and part of the works about the Zeeman effect on D α spectra had already been done. However, the asymmetric phenomena of D α emission spectra under the Zeeman effect were observed in process of analyzing the spectral data. To understand the asymmetric phenomena and acquire the useful local plasma information, an algorithm was proposed and used to analyze the asymmetry of the emission spectra under the Zeeman effect with all polarization components (π and ±σ). In the algorithm, the neutral atoms were considered to follow the Maxwell distribution on EAST, and I +σ ≠ I −σ was considered and set. Because of the line-averaged spectra along the viewing chord, the emission spectra were considered from two different regions: low-field side (LFS) and high-field side (HFS). Each spectral line was classified into three energy categories (the cold, warm, and hot) based on different atomic production processes in boundary recycling. The viewing angle θ (between the magnetic field B and the viewing chord), magnetic field B at two spectral emission positions (HFS and LFS) and the Doppler shift of all three energy categories of each spectral line were all considered in the algorithm. The effect of instrument function was also included here. The information of the boundary plasma were acquired, the reason for the asymmetric phenomena was discussed, and the boundary recycling during the discharge were studied in the paper. Based on fitting a statistical data of acquired fitting results, an important conclusion was acquired that the ratio of the spectral line intensity in HFS and LFS was proportional to the square of that of the corresponding magnetic field.

Elemental analysis of agriculture soil by a pulsed carbon dioxide (CO2) Laser Induced Breakdown Spectroscopy (LIBS)

Quick qualitative elemental analysis of agriculture soil has been made using a pulsed CO2 LIBS. The laser beam with different pulse energy was focused on agriculture soil sample under ambient of helium at atmospheric pressure (760 Torr) after the laser beam passes through a covering metal mesh. Emission spectra from the consequent plasma was recorded in wavelength range from 200 nm to 800 nm. It was found that by utilizing the mesh, intense plasma was generated immediately after the CO2 laser irradiation. It was seen that emission lines belong to salts, namely Ca, Mg, Na, K and metals such as Al, Si, Fe, Ti, Cr can certainly be identified. It was also found that the profile of the emission spectrum detected are basically relative similar to the standard soil, nevertheless the agriculture soil color is very different from the standard soil. Higher resolution and sensitivity optical multichannel analyzer (OMA) system is required to evaluate in greater detail the elemental composition of the soil samples.

Energy dependence of Cl emission lines in CO2 laser induced breakdown spectroscopy

Chlorine (Cl) detection using laser induced breakdown spectroscopy (LIBS) techniques in geology and environment samples is still challenging since the experimental conditions greatly influence the analytical performance of LIBS. Cl emission in LIBS must be studied carefully to find the optimum condition to allow Cl detection. In the present study, Cl emission was studied from polyvinyl chloride (PVC) sample containing Cl as major element. A Transversely Excited Atmosphere (TEA) carbon dioxide (CO2) laser was used for inducing plasma from the sample. Cl emission was investigated by varying the experimental conditions, especially energy of the laser pulse. The emission spectrum from the consequent plasma was detected using an Optical Multichannel Analyzer (OMA) system. It was found that Cl emission lines only can be obtained when helium was used as the surrounding gas. The strongest emission line of Cl I 837.59 nm in the infrared region cannot be detected even under helium surrounding gas. Instead, many ionic emission lines of Cl in ultraviolet regions including the strong ionic lines (Cl II 479.45 nm, Cl II 481.00 nm, Cl II 481.94 nm and the weak lines (Cl II 476. 86 nm, Cl II 478.13 nm, Cl II 489.67 nm, Cl II 490.47 nm and Cl II 491.77 nm) can unequivocally be detected. It was also found that the intensity of Cl emission lines critically depends on the energy of the laser pulse, namely the emission intensity of Cl lines increases sharply with energy. In present work, the highest intensity of Cl emission lines was obtained when the energy of the laser pulse was about 2500 mJ, giving strong and clear Cl emission lines with low background and relatively high signal to background ratio of more than 3.

Emission Spectral Profile of Salt in Laser-Induced Breakdown Spectroscopy (LIBS) on River Clamshell Sample

Since the river clamshell is commonly used as one of the raw materials for making lime betel widely consumed, inspection of its salt content is very important. This work is to study the profile of salt emission spectrum from the river clamshell sample inlaser-induced breakdown spectroscopy (LIBS). The observation of the general emission profile is possible thanking to the availability of the optical multichannel analyzer (OMA) system with a wide wavelength coverage from 200 nm-950 nm. LIBS apparatus used in this work consist of Nd-YAG (neodymium-doped yttrium aluminum garnet) laser and an OMA system equipped with an echelle spectrograph system. The river clamshell samples were collected from Panga River, Panga, Aceh Jaya, Aceh, Indonesia. The Panga river up streams to mountain of Gunong Ujeun, used to an intensive traditional mining location. The plasma generation was made by focusing the Nd-YAG laser beam on the clamshell sample under air surrounding gas at atmospheric pressure. There are two kinds of sample used, namely fresh sample without any treatment and pelletized sample. The result shows the emission spectrum in general consist of a large number of Ca emission lines, both atomic and ionic lines. However, several other salt emission lines such as Mg, Na, K, and Al also can be clearly observed at various wavelengths. This result suggests the emission spectrum of salt detected from the river clam sample are predominantly dominated by Ca emission lines.

Preliminary Study on Possibility Cl Detection in Soil by Means of The Unique Sub-target in a Transversely Excited Atmospheric Pressure (TEA) Carbon Dioxide (CO2) Laser Induced Breakdown Spectroscopy

A preliminary study on Cl detection in soil sample using LIBS has been carried out. The soil sample was mixed with silicon grease to allow attachment to the surface of a nickel plate acting as a sub-target. The laser used in this work is a TEA CO2 laser that operates at wavelength of 10.6μm with energy and pulse duration of 2.5 J and 200 ns, respectively. The laser beam was focused onto the sample using a zinc selenium lens (f = 200 mm) under air and helium surrounding gas at atmospheric pressure. The emission spectrum from the generated plasma was detected using an optical multichannel analyser (OMA)system consisting of a 0.32-m-focal length spectrograph with a grating of 1200 graves/mm and a 1024-channel photodiode detector array with a micro-channel plate intensifier. Soil sample used in this work is a standard soil sample mixed with NaCl solution at various concentrations. The results show that many emission lines due to salts such as Ca, Mg, Na and K can be detected clearly. Nevertheless, Cl emission line cannot be detected in soil sample, although the sample has been intentionally mixed with Cl, even when Cl content reaching 1000 ppm. It is therefore necessary to develop a new approach to allow LIBS techniques for detecting Cl in soil samples.

Temperature estimation using Boltzmann plot method of many calcium emission lines in laser plasma produced on river clamshell sample

Temperature as one very important characteristics of a laser-induced plasma was estimated using many calcium emission spectral lines. This was possible due to the availability of a wide coverage and high resolution optical multichannel analyser (OMA) system allowing a simultaneous detection of many emission spectral lines from one element. The plasma emission was produced after focusing an Nd-YAG (neodymium-doped yttrium aluminium garnet) laser onto a river clamshell samples under air as surrounding gas at low and high pressures. The emission spectrum was acquired using the OMA system equipped with an echelle spectrograph system. The clamshell sample was collected from Panga River, Panga, Aceh Jaya, Aceh, Indonesia. The plasma temperature estimation was carried out by Boltzmann plot method. All calcium spectral lines either atomic and ionic emission were identified including resonant emission spectral lines in the recorded spectrum. Boltzmann distribution function firstly was plotted for all identified calcium spectral lines either atomic and ionic emission including their respective resonant emission spectral lines. In the further stage, the resonant emission lines then were excluded from the Boltzmann plot. As the results, the estimated temperature changes significantly with the number emission lines included and also with inclusion of the resonant spectral lines. The plasma temperature heavily influenced by inclusion the resonant emission lines. Thus, this work demonstrated clearly the influence of number emission lines used in Boltzmann plot to the plasma temperature estimation. The results also demonstrated explicitly the apparent effect of self-absorption of the resonant spectral line in estimation the plasma temperature.

Plasma induced by a pulsed CO2 laser from powder samples mixed with silicone on metal subtarget and its possibility for detecting difficult salts of Cl, B, and S

Emission spectrum from plasma produced by a transversely excited atmosphere (TEA) carbon dioxide (CO2) laser from pure powder samples mixed with silicone grease attached to a nickel plate was studied. The pulsed CO2 laser operating at wavelength of 10.6 μm with energy and duration of the laser pulse is 2.5 J and 200 ns, respectively. The plasma was produced by focusing the laser beam onto the sample using a focusing lens (f = +200 mm) under air and helium surrounding gas at atmospheric pressure alternatively. The plasma emission spectrum was detected using an optical multichannel analyser (OMA) system equipped with a 0.32-m-focal length spectrograph. The spectrograph consists of a grating of 1200 graves/mm and a 1024-channel photodiode detector array with a micro-channel plate intensifier. The samples used this work are pure chemical powder samples. This technique was used to investigate emission spectral lines due to important salts but difficult to detect such as boron (B), chlorine (Cl) and sulphur (S) from powder samples. It was found that emission intensity detected from the produced plasma is remarkably higher in case using He as ambient gas compared with that using air. It was found that emission spectral lines due to B, Cl, and S can clearly be detected. Even though concentration of the salts (B, Cl, S) is very high since the samples used are pure chemical powder, however several emission spectral lines theoretically expected to appear with strong relative intensity displays relatively low intensity in the detected spectrum. This result confirms the difficulty for detecting the salts, especially chlorine (Cl) and sulphur (S). This technique basically promises a potential application for direct detection of B, Cl and S from powder samples, however new approaches must be developed to realise a high sensitive detection especially for Cl and S.

Identification of nickel emission lines using Nd:YAG laserinduced breakdown spectroscopy

Identification of nickel element (Ni) is necessary in various fields including agriculture, mining, and industries. In this study, rapid identification of nickel metal in was made by using laser-induced plasma spectroscopy method. Experimentally, a pulse laser beam (Nd:YAG laser, 1064 nm) was focused on a sample target to initiate a plasma. The plasma emission was detected by optical multichannel analyzer system to obtain the emission spectrum from the sample target. The target used was pure nickel metal plate and Indonesian currency coin containing Ni. The results show that the Ni lines can clearly be detected from the Ni plate at the wavelengths of neutral Nickel (Ni I) at wavelength of300.363, 305.432, 310.188, 313.411, 341.348, 345.289, 351.977, 356.637, 351.977, 356.637, 361.939, and 778.894 nm for neutral Ni lines and at the wavelength of 337.897 nm for ionic Ni line. It was also demonstrated that the Ni emission lines at the same wavelength in the Ni metal plate was also detected from the other sample of currency coin containing Ni. This certified that the present can be used to identify Ni emission in metal sample containing Ni.

Emission characteristics of copper using laser-induced breakdown spectroscopy at low pressure

Identification of copper (Cu) in metal is necessary to evaluate the quality of metal products. High-concentration of Cu in metal can make easily fragile of the metal. In this study, identification and emission characteristics of Cu were carried out by using laser-induced breakdown spectroscopy (LIBS). The sample used was Cu plate (99.99%) and Indonesian currency coin containing Cu. Experimentally, a pulse laser beam (Nd:YAG laser, 1064 nm, 7 ns) was irradiated on the material surface to induce a plasma. The plasma emission was detected by optical multichannel analyzer system to obtain emission spectrum of Cu. The results certified that many neutral Cu lines at 324.75, 327.40, 510.55, 515.32, and 521.82 nm, and ionic Cu lines at wavelengths of 406.81, and 657.71 nm were successfully detected. It has been confirmed that the Cu lines at the same wavelength was also detected from the Indonesian currency coin. However, the intensity of the Cu lines are much weaker for the case of coin target. Furthermore, the other element of aluminum (Al) was also identified in the coin sample at wavelength of 309.28 nm and 396.15 nm for neutral Al lines, and ionic Al line at wavelength of 660.92 nm.

Detection of salts in soil using transversely excited atmospheric (TEA) carbon dioxide (CO2) laser-induced breakdown spectroscopy (LIBS) by the aid of a metal mesh

In this work, a nickel metal mesh was used to allow a direct detection of salt in soil sample by LIBS utilizing unique characteristics of a TEA CO2. The metal mesh is placed in the front of the soil sample to prevent the soil sample from blowing off upon focusing the high pulsed laser beam irradiation. LIBS apparatus used in this work is a TEA CO2 laser operated at wavelength of 10.6 μm with pulse energy and duration of 3J and 200 ns, respectively. The laser beam was focused using a ZnSe lens (f = 200 mm) onto soil sample after passing through the metal mesh. The emission spectrum from the induced plasma was detected using an optical multichannel analyzer (OMA) system consisting of a 0.32-m-focal length spectrograph with a grating of 1200 graves/mm and a 1024-channel photodiode detector array with a micro-channel plate intensifier. The soil sample used is a standard soil and ordinary soil containing several salts such as Ca, Mg at high concentration. The LIBS experiment was carried out at high pressure surrounding gas of 1 atmosphere. It was observed that by the aid of the metal mesh, strong breakdown gas plasma can be produced just after TEA CO2 laser irradiation on soil sample without significant sample blowing off. It was found that emission lines from salts, Ca (Ca II 393. 3 nm, Ca II 396.3 nm, Ca I 422.5 nm), and also other salts including Mg and Na can clearly be detected with strong emission intensity and narrow spectral width. This result implies that a TEA CO2 LIBS assisted by the metal mesh (metal mesh method) can be used for direct analysis several salts such as Ca, Mg, and Na in soil sample.

Preliminary panoramic study of river calm muscle using neodymium:yttrium-aluminum-garnet (Nd: YAG) laser-induced breakdown spectroscopy (LIBS)

A wide coverage spectral investigation on the muscle of river calm sample has been carried out using laser-induced breakdown spectroscopy for examining the overall profile of the emission spectra from the produced plasma. The basic apparatus of LIBS system used is a Nd-YAG laser and wide coverage optical multichannel analyzer (OMA) system. The river clam samples used is collected from Panga River in Aceh Jaya Regency, Aceh, Indonesia up streaming in a mountain of Gunong Ujeun, which is used as a location of the intensive traditional mining activity. Assuming that heavy metal accumulated in the clam muscle, LIBS experiments were carried out on the muscle of the calm. The sample used was fresh muscle sliced and attached to a copper plate. Plasma was generated by focusing the laser beam on the sample surface under air surrounding gas at 1 atmosphere. It is found that there are only major elements of host organic, namely C, H, O, N and the minor element of salts can be detected from fresh the clam sample when using a high pulse laser energy under air surrounding at high pressure of 1 atmosphere. There is no emission lines from any metal can be detected. Several experimental parameters were explored to study the panoramic dynamic of the emission spectra. It is found that the lower energy and the lower pressure is better for obtaining better emission spectra showing the possibility for determination of the analyte.

Study on Emission Spectral Lines of Iron, Fe in Laser-Induced Breakdown Spectroscopy (LIBS) on Soil Samples

In this work, LIBS technique has been used for detection of heavy metal especially iron, Fe in soil sample. As there are a large number of emission spectral lines due to Fe and other constituents in soil, this study is intended to identify emission spectral lines of Fe and finally to find best fit emission spectral lines for carrying out a qualitative and quantitative analysis. LIBS apparatus used in this work consists of a laser system (Neodymium Yttrium Aluminum Garnet, Nd-YAG: Quanta Ray; LAB SERIES; 1,064 nm; 500 mJ; 8 ns) and an optical multichannel analyzer (OMA) system consisting of a spectrograph (McPherson model 2061; 1,000 mm focal length; f/8.6 Czerny- Turner) and an intensified charge coupled device (ICCD) 1024x256 pixels (Andor I*Star). The soil sample was collected from Banda Aceh city, Aceh, Indonesia. For spectral data acquisition, the soil sample has been prepared by a pressing machine in the form of pellet. The laser beam was focused using a high density lens (f=+150 mm) and irradiated on the surface of the pellet for generating luminous plasma under 1 atmosphere of air surrounding. The plasma emission was collected by an optical fiber and then sent to the optical multichannel analyzer (OMA) system for acquisition of the emission spectra. It was found that there are many Fe emission lines both atomic lines (Fe I) and ionic lines (Fe II) appeared in all detection windows in the wavelength regions, ranging from 200 nm to 1000 nm. The emission lines of Fe with strong intensities occurs together with emission lines due to other atoms such as Mg, Ca, and Si. Thus, the identification of emission lines from Fe is complicated by presence of many other lines due to other major and minor elements in soil. Considering the features of the detected emission lines, several emission spectral lines of Fe I (atomic emission line), especially Fe I 404.58 nm occurring at visible range are potential to be good candidate of analytical lines in relation to detection heavy metal pollution, Fe, in soil sample.

Analysis of the Zeeman effect on Dα spectra on the EAST tokamak**Project supported by the National Natural Science Foundation of China (Grant Nos. 11275231 and 11575249) and the National Magnetic Confinement Fusion Energy Research Program of China (Grant No. 2015GB110005).

Based on the passive spectroscopy, the atomic emission spectra in the boundary region of the plasma have been measured by a high resolution optical spectroscopic multichannel analysis (OSMA) system in EAST tokamak. The Zeeman splitting of the spectral lines has been observed. A fitting procedure by using a nonlinear least squares method was applied to fit and analyze all polarization π and components of the atomic spectra to acquire the information of the local plasma. The spectral line shape was investigated according to emission spectra from different regions (e.g., low-field side and high-field side) along the viewing chords. Each polarization component was fitted and classified into three energy categories (the cold, warm, and hot components) based on different atomic production processes, in consistent with the transition energy distribution by calculating the gradient of the spectral profile. The emission position, magnetic field intensity, and flow velocity of a deuterium atom were also discussed in the context.

Measurements of rotational and vibrational temperatures based on flame emission spectroscopy

This study addresses emission spectra of Air-ethanol and Air-kerosene flames by using optical multichannel analysis system (OMA). Experimental results show that there are several bands of molecular spectrum in a range from 275 to 600nm. Among them, the OH A2+X2r(300330 nm), the CH A2X2(410440 nm), and C2 A3gX3u (500 520 nm) emissions have the strongest intensity. In turn, the fine structures of OH (A2+X2r) and CH (A2X2) emission are studied by using a high resolution grating in experiment, and the distributions of spectra intensity are calculated at different rotational and vibrational temperatures based on the molecular spectroscopy. Moreover, by comparing the simulated spectra with the experimental spectra of OH (A2+X2r) and CH (A2X2) emissions, the rotational and the vibrational temperatures of Air-ethanol flame are determined in this paper.

Calculation of extracted ion beam particle distribution including within-extractor collisions from H-alpha Doppler shift measurements

Prototype long pulse ion sources are being developed and tested toward the goal of a deuterium beam extraction of 120 keV/65 A. The latest prototype source consists of a magnetic bucket plasma generator and a four-grid copper accelerator system with multicircular apertures of 568 holes. To measure the angular divergence and the ion species of the ion beam, an optical multichannel analyzer (OMA) system for a Doppler-shifted H-alpha lights was set up at the end of a gas-cell neutralizer. But the OMA data are very difficult to analyze due to a large background level on the top of the three energy peaks (coming from H(+), H(2) (+), and H(3) (+)). These background spectra in the OMA signals seem to result from partially accelerated ion beams in the accelerator. Extracted ions could undergo a premature charge exchange as the accelerator column tends to have a high hydrogen partial pressure from the unused gas from the plasma generator, resulting in a continuous background of partially accelerated beam particles at the accelerator exit. This effect is calculated by accounting for all the possible atomic collision processes and numerically summing up three ion species across the accelerator column. The collection of all the atomic reaction cross sections and the numerical summing up will be presented. The result considerably depends on the background pressure and the ion beam species ratio (H(+), H(2) (+), and H(3) (+)). This effect constitutes more than 20% of the whole particle distribution. And the energy distribution of those suffering from collisions is broad and shows a broad maximum in the vicinity of the half and the third energy region.

Resonance fluorescence spectroscopy in laser-induced cavitation bubbles

Laser-induced breakdown spectroscopy (LIBS) in liquids using a double-pulse Q-switched Nd:YAG laser system has provided reliable results that give trace detection limits in water. Resonant laser excitation has been added to enhance detection sensitivity. A primary laser pulse (at 532 nm), transmitted via an optical fiber, induces a cavitation bubble and shockwave at a target immersed in a 10 mg l(-1)-100 mg l(-1) indium (In) water suspension. The low-pressure rear of the shockwave induces bubble expansion and a resulting reduction in cavity pressure as it extends away from the target. Shortly before the maximum diameter is expected, a secondary laser pulse (also at 532 nm) is fed into the bubble in order to reduce quenching processes. The plasma field generated is then resonantly excited by a fiber-guided dye laser beam to increase detection selectivity. The resulting resonance fluorescence emission is optically detected and processed by an intensified optical multichannel analyzer system.