Analysis of Organic Powder Samples by Using the Metal-Assisted Subtarget Effect in a Transversely-Excited Atmospheric (TEA) CO2 Laser-Induced He Gas Plasma at 1 atm

Ali Khumaeni,Hideaki Niki,Yoji Deguchi,Kazuyoshi Kurihara,Kiichiro Kagawa,Yong Inn Lee 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6

A novel technique for analysis of organic powder samples has been developed utilizing a metal subtarget-assisted gas plasma induced by using a TEA CO2 laser under He gas at atmospheric pressure. In this technique, the sample was filled in a hole (diameter of 8 mm and thickness of 2 mm) made of plastic plate (10 mm × 10 mm × 2 mm). The plastic holder filled with the sample was then sandwiched between two Cu plates (25 mm × 25 mm × 0.3 mm). One Cu plate, which had a hole with a diameter of 2.5 mm, functions to suppress the blowing-off of the sample, and the other served as a subtarget. When the TEA CO2 laser (1.5 J, 10.6 μm) was successively irradiated onto the sample’s surface passing through the hole of the Cu plate, a hole (2.5 mm in diameter and 2 mm in depth) was produced inside the sample, and the laser beam directly impinged on the subtarget. Once the laser beam had struck the subtarget, a strong subtarget-assisted gas plasma was induced. The initial gas plasma was confined in the hole region, and in later stage, the gas plasma expanded with a hemispherical shape (diameter of 1 cm). The fine particles of the sample were vaporized and effectively dissociated and atomized in the hole, and the atoms moved to the hemispherical plasma region to be excited through He meta-stable atoms. Using this method, an excellent linear calibration curve with zero intercept was made using a herb medicine containing different concentrations of Cr. The detection limits of Cr and Pb in the herb medicine were around 1 and 5 mg/kg, respectively. A novel technique for analysis of organic powder samples has been developed utilizing a metal subtarget-assisted gas plasma induced by using a TEA CO2 laser under He gas at atmospheric pressure. In this technique, the sample was filled in a hole (diameter of 8 mm and thickness of 2 mm) made of plastic plate (10 mm × 10 mm × 2 mm). The plastic holder filled with the sample was then sandwiched between two Cu plates (25 mm × 25 mm × 0.3 mm). One Cu plate, which had a hole with a diameter of 2.5 mm, functions to suppress the blowing-off of the sample, and the other served as a subtarget. When the TEA CO2 laser (1.5 J, 10.6 μm) was successively irradiated onto the sample’s surface passing through the hole of the Cu plate, a hole (2.5 mm in diameter and 2 mm in depth) was produced inside the sample, and the laser beam directly impinged on the subtarget. Once the laser beam had struck the subtarget, a strong subtarget-assisted gas plasma was induced. The initial gas plasma was confined in the hole region, and in later stage, the gas plasma expanded with a hemispherical shape (diameter of 1 cm). The fine particles of the sample were vaporized and effectively dissociated and atomized in the hole, and the atoms moved to the hemispherical plasma region to be excited through He meta-stable atoms. Using this method, an excellent linear calibration curve with zero intercept was made using a herb medicine containing different concentrations of Cr. The detection limits of Cr and Pb in the herb medicine were around 1 and 5 mg/kg, respectively.

Reconstruction of chemical fingerprints from an individual's time-delayed, overlapped fingerprints via laser-induced breakdown spectrometry (LIBS) and Raman spectroscopy

Yang, Jun-Ho,Yoh, Jack J. Elsevier 2018 Microchemical Journal Vol.139 No.-

<P><B>Abstract</B></P> <P>Laser-induced breakdown spectroscopy (LIBS) is a method for atomic emission analysis that can be used to analyze the chemical composition of samples in the forensic investigations. The combined effort of extracting, analyzing, and restoring latent fingerprints at crime scenes is an important step toward successful arrests, and hence, the purpose of this research is to estimate the temporal sequence at which a fingerprint was imprinted from an individual. The difference in the laser spectrum from a latent fingerprint at times from 0 to 60min after it was left was analyzed using LIBS and Raman spectroscopy, both of which require no chemical pre-treatment of the sample. We found that the signal intensity changes with time, 60min after the imprint was made for the wavelengths of CN band, fatty acid, amino acid, and oil components. Based on these preliminary findings, the chemometric analysis was performed on the spectrum data obtained from 60min of exposure time and the time-sequenced overlapping fingerprints were distinguished, which were imprinted at intervals of 10, 20, 30, and 40min using SIMCA and PLS-DA classification methods.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Aging factor of latent fingerprint was analyzed using LIBS and Raman. </LI> <LI> Time sequencing of an individual's latent fingerprints was performed. </LI> <LI> Time-delayed, overlapped fingerprints were separated. </LI> </UL> </P>

A unique technique of laser-induced breakdown spectroscopy using transversely excited atmospheric CO₂ laser for the sensitive analysis of powder samples

Khumaeni, A.,Niki, H.,Fukumoto, K.i.,Deguchi, Y.,Kurihara, K.,Kagawa, K.,Lee, Y.I. Elsevier 2011 Current Applied Physics Vol.11 No.3

A sensitive analysis of powder samples has successfully been conducted using a strong gas breakdown plasma induced by assisting a metal mesh and a metal subtarget utilizing a transversely excited atmospheric (TEA) CO<SUB>2</SUB> laser; the metal mesh and the metal subtarget were placed on the front side and backside of the sample, respectively. The experiment was made at high pressure of air surrounding gas. In this study, the TEA CO<SUB>2</SUB> laser (1.5 J, 200 ns) was focused on the sample surface through the metal mesh. At the initial stage, a strong gas breakdown plasma was initiated by the assist of the metal mesh and finally enhanced by the metal subtarget after the laser beam struck on the metal subtarget's surface through a hole inside the sample. The strong gas breakdown plasma can effectively be applied to completely dissociate and excite the ablated atoms from the sample. Using this technique, an excellent calibration curve with zero intercept has been made using herb medicine powder sample containing different concentrations of Zn. For sensitive analysis, a detection of hazard element of Cr in commercial supplement was also carried out. The detection limit of Cr was estimated to be around 0.6 mg/kg. This present technique has high possibility to realize the analysis of powder samples with high precision and high sensitivity.

레이저유도붕괴분광법을 활용한 토양의 정량분석

장용선(Yong-Seon Zhang),이계준(Gye-Jun Lee),이정태(Jeong-Tae Lee),황선웅(Seon-Woong Hwang),진용익(Yong-Ik Jin),박찬원(Chan-Won Park),문용희(Yong-Hee Moon) 한국토양비료학회 2009 한국토양비료학회지 Vol.42 No.5

레이저 유도붕괴 분광법(LIBS)은 물질상태(고체, 액체, 기체)에 상관없이 신체 접촉시 오염 우려 및 미량 시료도 전처리 없이 동시에 많은 종류의 원소 분석으로 분석과정이 단순하고 신속하게 분석이 가능하며, 소형화된 레이저의 개발로 시료의 직접적인 채취가 어려운 조건의 현장분석에도 적합하다. 농산물 안정성 평가나 친환경 농업 및 정밀농업을 위한 조사 등에 활용될 수 있는 비파괴 실시간 정량분석기술로서 LIBS 분석법의 토양분석 가능성을 평가하고자 표준광물, 미국의 표준기술연구소의 표준토양, 미국 테네시주 초지 및 밭토양을 대상으로 토양 구성성분의 정성ㆍ정량적 분석에 필요한 측정조건을 조사하고 이를 토대로 LIBS에 의한 농도값과 기존의 화학분석법을 통해 측정한 결과를 비교하였다. LIBS 측정은 펄스형 Nd:YAG 레이저(Minilite Ⅱ, Continuum, Santa Clara, CA)에서 나오는 1064 ㎚ 에너지 파장의 광원을 시편의 플라즈마를 생성시키는데 사용하였고, 25 mJ/pulse 여기 에너지 빔을 펄스폭 35 ns, 펄스 반복 주기 10 ㎐, 노출시간 10 s 동안 시료의 표면에 조사하였다. LIBS 분광은 0.03 ㎚의 해상력으로 200 ㎚에서 600 ㎚의 영역에서 50 m 이하로 분쇄하여 원형 펠렛 형태로 압축시킨 시료를 10 rpm의 속도로 회전시키면서 상온 상압의 실험실 조건에서 수행되었다. LIBS를 이용한 토양 중 주요한 원소의 적정 파장(㎚)은 Al(I) 309.2 ㎚, Ca(I) 422.6 ㎚, Fe(I) 406.4 ㎚, Mg(I) 285.2 ㎚, Na(I) 589.2 ㎚, Si(I) 288.2 ㎚, Ti(I) 398.9 ㎚ 이었다. LIBS의 피크강도가 물질 중 원소의 농도가 증가됨에 따라 각 원소의 특정 파장대에서 일정하게 증가되는 것으로 나타나고 있으나 표준물질의 LIBS의 신호비와 원소비를 통해 측정된 검량곡선의 상관계수(r2)는 0.863에서 0.977의 범위로 원소별로 상이할 뿐만 아니라 0.98에 미치지 못하였다. 또한, 토양중 분석대상원소에 대하여 기존 ICP-AES에 의한 표준방법으로 분석된 시료의 측정값과 비교하여 상대적인 오차는 대략적으로 (-)40%에서 80%이상이며, 평균오차는 32.2%로 표준척도 20% 이상을 초과하였다. LIBS에 의한 토양분석은 토양의 조성과 입자의 크기에 따른 매질효과(matrix effect)로 표준물질의 검량곡선에서 결정계수가 낮고, 원소별 함량도 기준의 표준방법과 비교할 때 오차가 컸다. 따라서 LIBS에 의한 토양분석은 정성적인 분석 수준의 정밀도를 보였으며, 토양 매질의 영향을 최소화하기 위하여 기존의 분쇄ㆍ펠렛형 시료조제 및 회전측정 이외의 다양한 토양매질의 표준물질(standard reference material)의 확보, 새로운 전처리 방법 및 측정상 방법개선 등 신뢰성 있는 정량 분석을 위한 노력이 필요할 것으로 사료된다. Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 ㎚(0.03 ㎚ interval) with a Nd:YAG laser at 532 ㎚, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 ㎐. The optimum wavelength(λ㎚) of LIBS for estimating soil and plant elements were 308.2 ㎚ for Al, 428.3 ㎚ for Ca , 247.8 ㎚ for T-C, 438.3 ㎚ for Fe, 766.5 ㎚ for K , 85.2 ㎚ for Mg, 330.2 ㎚ for Na, 213.6 ㎚ for P, 180.7 ㎚ for S, 288.2 ㎚ for Si, and 351.9 ㎚ for Ti, respectively. Coefficients of determination(r²) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

A unique technique of laser-induced breakdown spectroscopy using transversely excited atmospheric CO_2 laser for the sensitive analysis of powder samples

Ali Khumaeni,Hideaki Niki,Ken-ichi Fukumoto,Yoji Deguchi,Kazuyoshi Kurihara,Kiichiro Kagawa,이용인 한국물리학회 2011 Current Applied Physics Vol.11 No.3

A sensitive analysis of powder samples has successfully been conducted using a strong gas breakdown plasma induced by assisting a metal mesh and a metal subtarget utilizing a transversely excited atmospheric (TEA) CO_2 laser; the metal mesh and the metal subtarget were placed on the front side and backside of the sample, respectively. The experiment was made at high pressure of air surrounding gas. In this study, the TEA CO_2 laser (1.5 J, 200 ns) was focused on the sample surface through the metal mesh. At the initial stage, a strong gas breakdown plasma was initiated by the assist of the metal mesh and finally enhanced by the metal subtarget after the laser beam struck on the metal subtarget’s surface through a hole inside the sample. The strong gas breakdown plasma can effectively be applied to completely dissociate and excite the ablated atoms from the sample. Using this technique, an excellent calibration curve with zero intercept has been made using herb medicine powder sample containing different concentrations of Zn. For sensitive analysis, a detection of hazard element of Cr in commercial supplement was also carried out. The detection limit of Cr was estimated to be around 0.6 mg/kg. This present technique has high possibility to realize the analysis of powder samples with high precision and high sensitivity.

분광분석을 통한 레이저 삭마 알루미늄과 산소의 연소반응 해석

김창환(Chang-hwan Kim),여재익(Jack) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.43

Laser-induced combustions and explosions generated by high laser irradiances were explored by Laser-Induced Breakdown Spectroscopy (LIBS) in rich, and stoichiometric conditions. The laser used for target ablation is a Q-switched Nd:YAG laser with 7 ㎱ pulse duration at wavelength of 1064 ㎚ laser energies from 40 mJ to 2500 mJ (6.88 x 1010 - 6.53 x 1011 W/㎝2). The plasma light source from aluminum detected by the echelle grating spectrometer and coupled to the gated ICCD(a resolution (λ/Δλ) of 5000). This spectroscopic study has been investigated for obtaining both the atomic signals of aluminum (fuel) ? oxygen (oxidizer) and the calculated ambient condition (plasma temperature and electron density). The essence of the paper is observing specific electron density ratio which can support the processes of combustion and explosion between ablated aluminum plume and oxygen from air by inducing high power laser.

A Novel Classification of Polymorphs Using Combined LIBS and Raman Spectroscopy

한동우,여재익,김대형,최수진 한국광학회 2017 Current Optics and Photonics Vol.1 No.4

Combined LIBS-Raman spectroscopy has been widely studied, due to its complementary capabilities asan elemental analyzer that can acquire signals of atoms, ions, and molecules. In this study, the classificationof polymorphs was performed by laser-induced breakdown spectroscopy (LIBS) to overcome the limitationin molecular analysis; the results were verified by Raman spectroscopy. LIBS signals of the CaCO3polymorphs calcite and aragonite, and CaSO4․ 2H2O (gypsum) and CaSO4 (anhydrite), were acquired usinga Nd:YAG laser (532 nm, 6 ns). While the molecular study was performed using Raman spectroscopy,LIBS could also provide sufficient key data for classifying samples containing different molecular densitiesand structures, using the peculiar signal ratio of 5s→4p for the orbital transition of two polymorphs thatcontain Ca. The basic principle was analyzed by electronic motion in plasma and electronic transition inatoms or ions. The key factors for the classification of polymorphs were the different electron quantitiesin the unit-cell volume of each sample, and the selection rule in electric-dipole transitions. The presentwork has extended the capabilities of LIBS in molecular analysis, as well as in atomic and ionic analysis.

Elemental composition of Arctic soils and aerosols in Ny-Alesund measured using laser-induced breakdown spectroscopy

Kim, G.,Yoon, Y.J.,Kim, H.A.,Cho, H.j.,Park, K. Pergamon Press ; Elsevier Science Ltd 2017 Spectrochimica acta. Part B, Atomic spectroscopy Vol.134 No.-

Two laser-induced breakdown spectroscopy (LIBS) systems (soil LIBS and aerosol LIBS) were used to determine the elemental composition of soils and ambient aerosols less than 2.5μm in Ny-Alesund, Svalbard (the world's most northerly human settlement). For soil LIBS measurements, matrix effects such as moisture content, soil grain size, and surrounding gas on the LIBS response were minimized. When Ar gas was supplied onto the soil sample surfaces, a significant enhancement in LIBS emission lines was observed. Arctic soil samples were collected at 10 locations, and various elements (Al, Ba, C, Ca, Cu, Fe, H, K, Mg, Mn, N, Na, O, Pb, and Si) were detected in soils. The elemental distribution in arctic soils was clearly distinguishable from those in urban and abandoned mining soils in Korea. Moreover, the concentrations of most of anthropogenic metals were fairly low, and localized sources in extremely close proximity affected the elevated level of Cu in the soil samples derived from Ny-Alesund. The number of elements detected in aerosols (C, Ca, H, K, Mg, Na, and O) was lower than those determined in soils. The elements in aerosols can mainly originate from minerals and sea salts. The elemental distribution in aerosols was also clearly distinguishable from that in soils, suggesting that the resuspension of local soil particles by wind erosion into aerosols was minimal. The daily variation of particle number concentration (RSD=71%) and the elements in aerosols (RSD=25%) varied substantially, possibly due to fluctuating air masses and meteorological conditions.

Study on the spectroscopic reconstruction of explosive-contaminated overlapping fingerprints using the laser-induced plasma emissions

Yang, Jun-Ho,Yoh, Jai-Ick The Korean Society of Analytical Science 2020 분석과학 Vol.33 No.2

Reconstruction and separation of explosive-contaminated overlapping fingerprints constitutes an analytical challenge of high significance in forensic sciences. Laser-induced breakdown spectroscopy (LIBS) allows real-time chemical mapping by detecting the light emissions from laser-induced plasma and can offer powerful means of fingerprint classification based on the chemical components of the sample. During recent years LIBS has been studied one of the spectroscopic techniques with larger capability for forensic sciences. However, despite of the great sensitivity, LIBS suffers from a limited detection due to difficulties in reconstruction of overlapping fingerprints. Here, the authors propose a simple, yet effective, method of using chemical mapping to separate and reconstruct the explosive-contaminated, overlapping fingerprints. A Q-switched Nd:YAG laser system (1064 nm), which allows the laser beam diameter and the area of the ablated crater to be controlled, was used to analyze the chemical compositions of eight samples of explosive-contaminated fingerprints (featuring two sample explosive and four individuals) via the LIBS. Then, the chemical validations were further performed by applying the Raman spectroscopy. The results were subjected to principal component and partial least-squares multivariate analyses, and showed the classification of contaminated fingerprints at higher than 91% accuracy. Robustness and sensitivity tests indicate that the novel method used here is effective for separating and reconstructing the overlapping fingerprints with explosive trace.

Influence of water content on the laser-induced breakdown spectroscopy analysis of human cell pellet

Moon, Y.,Han, J.H.,Lee, J.J.,Jeong, S. Pergamon Press ; Elsevier Science Ltd 2015 Spectrochimica acta. Part B, Atomic spectroscopy Vol.114 No.-

The effects of water content change in a biological sample on the emission signal intensity and intensity ratio during LIBS analysis were investigated. To examine the effects of water content only avoiding matrix effects, a homogeneous human cell pellet consisting of cultured human immortalized keratinocyte cell only was used as the sample. LIBS spectra of the human cell pellet sample produced with a Q-switched Nd:YAG laser (λ=532nm, τ=5ns, top-hat profile) and a six-channel CCD spectrometer (spectral range=187-1045nm, spectral resolution=0.1 nm) revealed that most of the emission lines observed from a tissue sample were also observable from the human cell pellet. The intensity and intensity ratio of the emission lines varied significantly as the water content of the human cell pellet was changed. It was found that a typically selected internal standard in LIBS analysis of biological samples such as carbon could produce inconsistent results, whereas the ratio of properly selected emission lines such as Mg(II) 280.270nm and Ca(II) 396.847nm was nearly independent of sample water content.