TY - JOUR A1 - Gornushkin, Igor B. A1 - Smith, B.W. A1 - Panne, Ulrich A1 - Omenetto, N. T1 - Laser-induced breakdown spectroscopy combined with spatial heterodyne spectroscopy JF - Applied spectroscopy N2 - A spatial heterodyne spectrometer (SHS) is tested for the first time in combination with laser-induced breakdown spectroscopy (LIBS). The spectrometer is a modified version of the Michelson interferometer in which mirrors are replaced by diffraction gratings. The SHS contains no moving parts and the gratings are fixed at equal distances from the beam splitter. The main advantage is high throughput, about 200 times higher than that of dispersive spectrometers used in LIBS. This makes LIBS-SHS a promising technique for low-light standoff applications. The output signal of the SHS is an interferogram that is Fourier-transformed to retrieve the original plasma spectrum. In this proof-of-principle study, we investigate the potential of LIBS-SHS for material classification and quantitative analysis. Brass standards with broadly varying concentrations of Cu and Zn were tested. Classification via principal component analysis (PCA) shows distinct groupings of materials according to their origin. The quantification via partial least squares regression (PLS) shows good precision (relative standard deviation , 10%) and accuracy (within 6 5% of nominal concentrations). It is possible that LIBS-SHS can be developed into a portable, inexpensive, rugged instrument for field applications. KW - Spatial heterodyne spectroscopy KW - Laser-induced breakdown spectroscopy KW - Fourier transform spectroscopy KW - LIBS KW - Laser-induced plasma KW - Interferometry PY - 2014 DO - https://doi.org/10.1366/14-07544 SN - 0003-7028 SN - 1943-3530 VL - 68 IS - 9 SP - 1076 EP - 1084 PB - Society for Applied Spectroscopy CY - Frederick, Md. AN - OPUS4-32163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Shabanov, Sergej V. A1 - Panne, Ulrich T1 - Abel inversion applied to a transient laser induced plasma: implications from plasma modeling JF - Journal of analytical atomic spectrometry N2 - We test the effects of non-uniformity, non-transparency, and non-stationarity of a laser-induced plasma on the results obtained by the Abel inversion method. The method is commonly used for obtaining spatially resolved emissivity of axially symmetric non-homogeneous radiating objects. Besides the axial symmetry, the plasma is assumed to be optically thin. As the method addresses a certain plasma state, the plasma is required to be stationary during measurements. It is difficult to satisfy the aforementioned conditions for transient laser induced plasmas. As such the plasmas are not stationary; they have steep gradients of thermodynamic parameters that rapidly vary during the plasma evolution. Therefore, any conclusion based on time-integrated measurements and the corresponding data processing should account for these effects. In this work, we use the collision-dominated plasma model to generate time- and spatially resolved synthetic spectra. The spectra are processed by executing the Abel inversion using two numerical algorithms. Thus obtained spatially resolved plasma parameters (emissivity, temperature, and number density) are compared with the exact parameters used to set up the model. In doing so, the accuracy of the Abel inversion method is assessed. Special attention is paid to the dynamic aspect of the expanding plasma and possible errors which result from time-integrated measurements. PY - 2011 DO - https://doi.org/10.1039/c1ja10044k SN - 0267-9477 SN - 1364-5544 VL - 26 IS - 7 SP - 1457 EP - 1465 PB - Royal Society of Chemistry CY - London AN - OPUS4-25824 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Shabanov, Sergej V. A1 - Merk, Sven A1 - Tognoni, E. A1 - Panne, Ulrich T1 - Effects of non-uniformity of laser induced plasma on plasma temperature and concentrations determined by the Boltzmann plot method: implications from plasma modeling JF - Journal of analytical atomic spectrometry PY - 2010 DO - https://doi.org/10.1039/C0JA00016G SN - 0267-9477 SN - 1364-5544 VL - 25 SP - 1643 EP - 1653 PB - Royal Society of Chemistry CY - London AN - OPUS4-22942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Panne, Ulrich A1 - Winefordner, J. D. T1 - Linear correlation for identification of materials by laser induced breakdown spectroscopy: Improvement via spectral filtering and masking JF - Spectrochimica acta B N2 - The purpose of this work is to improve the performance of a linear correlation method used for material identification in laser induced breakdown spectroscopy. The improved correlation procedure is proposed based on the selection and use of only essential spectral information and ignoring empty spectral fragments. The method is tested on glass samples of forensic interest. The 100% identification capability of the new method is demonstrated in contrast to the traditional approach where the identification rate falls below 100% for many samples. KW - Correlation analysis KW - Linear correlation KW - Material identification KW - Laser induced plasma KW - LIBS PY - 2009 DO - https://doi.org/10.1016/j.sab.2009.07.038 SN - 0584-8547 SN - 0038-6987 VL - 64 IS - 10 SP - 1040 EP - 1047 PB - Elsevier CY - Amsterdam AN - OPUS4-20621 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Panne, Ulrich T1 - Radiative models of laser-induced plasma and pump-probe diagnostics relevant to laser-induced breakdown spectroscopy JF - Spectrochimica acta B N2 - The paper describes past and present efforts in modeling of laser-induced plasma and overviews plasma diagnostics carried out by pump-probe techniques. Besides general information on existing plasma models, the emphasis is given to models relevant to spectrochemical analysis, i.e. models of radiating plasma. Special attention is paid to collisional-radiative (CR) and collisional-dominated (CD) plasma models where radiative processes play an important role. Also, calibration-free (CF) models are considered which may endow with the possibility for standardless spectroscopic analysis. In the diagnostic part, only methods based on the use of additional diagnostic tools (auxiliary lasers, optics, and probes) are described omitting those based on plasma own radiation. A short review is provided on image-based diagnostics (shadowgraphy, schlieren, and interferometry), absorption and fluorescence, Langmuir probe, and less frequently used cavity ringdown and Thomson scattering methods. KW - Laser ablation KW - Modeling KW - Plasma diagnostics KW - Laser-induced breakdown spectroscopy PY - 2010 DO - https://doi.org/10.1016/j.sab.2010.03.021 SN - 0584-8547 SN - 0038-6987 VL - 65 IS - 5 SP - 345 EP - 359 PB - Elsevier CY - Amsterdam AN - OPUS4-24003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Merk, Sven A1 - Demidov, Alexandr A1 - Panne, Ulrich A1 - Shabanov, Sergej V. A1 - Smith, B.W. A1 - Omenetto, N. T1 - Tomography of single and double pulse laser-induced plasma using Radon transform technique JF - Spectrochimica acta B N2 - The Radon transform tomography is used for reconstruction of the emissivity distribution in single- (SP) and double-pulse (DP) laser induced plasmas in orthogonal geometry. The orthogonal DP plasma is intrinsically asymmetric and thus suitable for the Radon reconstruction. The DP plasma consists of two plasmas separated by a short time interval of ~ 1 µs. The first plasma is created in air near the surface of a Si wafer and is followed (pre-ablation mode) or preceded (post-ablation mode) by the second plasma induced on this surface. A spectrometer moves in a semi-circular path around the plasma keeping the plasma in the rotation center. The optical detection is arranged so that a thin plasma layer parallel to the target surface is monitored. The axial symmetry of the SP plasma is investigated by comparing data from the Abel inversion taken at different angles and Radon reconstruction. The multi-angle measurements are used to estimate errors of the Abel reconstruction due to asymmetries of the plasma. Time-resolved Radon reconstruction in white light is performed for the DP plasma in both pre- and post-ablation modes. In the former case, the effect of ablated aerosol on the formation of the air plasma is monitored. In the latter case, a formation of an asymmetric compression shock created by the target plasma inside the air plasma is visualized. This observation is supported by computer simulations. An interaction of the two plasmas is studied by spectrally resolved Radon reconstruction revealing a complex distribution of target and ambient species inside the plasma at all studied delay times. Overall, it is demonstrated that Radon-based tomography is an informative tool to study transient asymmetric laser induced plasmas. KW - Radon transform tomography of SP KW - DP laser induced plasma KW - LIBS KW - Orthogonal double pulse plasma PY - 2012 DO - https://doi.org/10.1016/j.sab.2012.06.033 SN - 0584-8547 SN - 0038-6987 VL - 76 SP - 203 EP - 213 PB - Elsevier CY - Amsterdam AN - OPUS4-27438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eschlböck-Fuchs, S. A1 - Huber, N. A1 - Ahamer, C. M. A1 - Hechenberger, J. G. A1 - Kolmhofer, P. J. A1 - Heitz, J. A1 - Rössler, R. A1 - Demidov, Alexander A1 - Schmid, Thomas A1 - Gornushkin, Igor B. A1 - Panne, Ulrich A1 - Pedarnig, J. D. T1 - Application of laser-induced breakdown spectroscopy for the analysis of slags in industrial steel production T2 - Tagungsband – 11. Kolloquium Prozessanalytik N2 - Laser-induced breakdown spectroscopy (LIBS) is a fast and versatile technique for (semi) quantitative element analysis of solids, liquids, gases, and particulate matter. The LIBS method is used for optical sensing in various branches of industrial production. In the contribution we review some of our recent results on LIBS analysis of slags from secondary metallurgy in industrial steel making. Major oxides in steel slags are measured at-line and after homogenization using a calibration-free (CF) method. Two approaches for CF analysis based on the Boltzmann plot method and on the calculation of synthetic spectra are compared for the analysis of quaternary oxides. We also present the research in cooperation with our industrial partners in the process-analytical chemistry network PAC. T2 - 11. Kolloquium Arbeitskreis Prozessanalytik CY - Vienna, Austria DA - 30.11.2015 KW - Laser-induced breakdown spectroscopy (LIBS) KW - Process analytical technology KW - Steel slag PY - 2015 PB - Plandruck+ Gesellschaft m.b.H. CY - Wien AN - OPUS4-39005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eschlböck-Fuchs, S. A1 - Demidov, Alexander A1 - Gornushkin, Igor B. A1 - Schmid, Thomas A1 - Rössler, R. A1 - Huber, N. A1 - Panne, Ulrich A1 - Pedarnig, J. D. T1 - Tomography of homogenized laser-induced plasma by Radon transform technique JF - Spectrochimica Acta B N2 - Tomography of a laser-induced plasma in air is performed by inverse Radon transform of angle-resolved plasma images. Plasmas were induced by single laser pulses (SP), double pulses (DP) in collinear geometry, and by a combination of single laser pulses with pulsed arc discharges (SP-AD). Images of plasmas on metallurgical steel slags were taken at delay times suitable for calibration-free laser-induced breakdown spectroscopy (CFLIBS). Delays ranged from few microseconds for SP and DP up to tens of microseconds for SP-AD excitation. The white-light and the spectrally resolved emissivity ε(x,y,z) was reconstructed for the three plasma excitation schemes. The electron number density Ne(x,y,z) and plasma temperature Te(x,y,z) were determined from Mg and Mn emission lines in reconstructed spectra employing the Saha-Boltzmann plot method. The SP plasma revealed strongly inhomogeneous emissivity and plasma temperature. Re-excitation of plasma by a second laser pulse (DP) and by an arc discharge (SP-AD) homogenized the plasma and reduced the spatial variation of ε and Te. The homogenization of a plasma is a promising approach to increase the accuracy of calibration-free LIBS analysis of complex materials. KW - Plasma tomography KW - Laser induced plasma KW - Radon transform technique KW - Laser induced breakdown spectroscopy (LIBS) KW - Steel slag KW - Calibration-free analysis PY - 2016 DO - https://doi.org/10.1016/j.sab.2016.07.007 VL - 123 SP - 59 EP - 67 PB - Elsevier B.V. AN - OPUS4-37452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Demidov, Alexandr A1 - Eschlböck-Fuchs, S. A1 - Kazakov, Alexander Ya. A1 - Gornushkin, Igor B. A1 - Kolmhofer, P. J. A1 - Pedarnig, J. D. A1 - Huber, N. A1 - Heitz, J. A1 - Schmid, Thomas A1 - Rössler, R. A1 - Panne, Ulrich T1 - Monte Carlo standardless approach for laser induced breakdown spectroscopy based on massive parallel graphic processing unit computing JF - Spectrochimica Acta B N2 - The improved Monte-Carlo (MC) method for standard-less analysis in laser induced breakdown spectroscopy (LIBS) is presented. Concentrations in MC LIBS are found by fitting model-generated synthetic spectra to experimental spectra. The current version of MC LIBS is based on the graphic processing unit (GPU) computation and reduces the analysis time down to several seconds per spectrum/sample. The previous version of MC LIBS which was based on the central processing unit (CPU) computation requested unacceptably long analysis times of 10's minutes per spectrum/sample. The reduction of the computational time is achieved through the massively parallel computing on the GPU which embeds thousands of co-processors. It is shown that the number of iterations on the GPU exceeds that on the CPU by a factor > 1000 for the 5-dimentional parameter space and yet requires > 10-fold shorter computational time. The improved GPU-MC LIBS outperforms the CPU-MS LIBS in terms of accuracy, precision, and analysis time. The performance is tested on LIBS-spectra obtained from pelletized powders of metal oxides consisting of CaO, Fe2O3, MgO, and TiO2 that simulated by-products of steel industry, steel slags. It is demonstrated that GPU-based MC LIBS is capable of rapid multi-element analysis with relative error between 1 and 10's percent that is sufficient for industrial applications (e.g. steel slag analysis). The results of the improved GPU-based MC LIBS are positively compared to that of the CPU-based MC LIBS as well as to the results of the standard calibration-free (CF) LIBS based on the Boltzmann plot method. KW - Monte Carlo simulation KW - Parallel computing KW - Calibration-free laser-induced breakdown spectroscopy KW - Post-breakdown laser induced plasma KW - Quaternary oxides PY - 2016 DO - https://doi.org/10.1016/j.sab.2016.09.016 VL - 125 SP - 97 EP - 102 PB - Elsevier B.V. AN - OPUS4-38489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bierstedt, Andreas A1 - Kersten, H. A1 - Glaus, Reto A1 - Gornushkin, Igor B. A1 - Panne, Ulrich A1 - Riedel, Jens T1 - Characterization of an airborne laser-spark ion source for ambient mass spectrometry JF - Analytical Chemistry N2 - An airborne laser plasma is suggested as an ambient ion source for mass spectrometry. Its fundamental physical properties, such as an excellent spatial and temporal definition, high electron and ion densities and a high effective cross section in maintaining the plasma, make it a promising candidate for future applications. For deeper insights into the plasma properties, the optical plasma emission is examined and compared to mass spectra. The results show a seemingly contradictory behavior, since the emitted light reports the plasma to almost entirely consist of hot elemental ions, while the corresponding mass spectra exhibit the formation of intact molecular species. Further experiments, including time- resolved shadowgraphy, spatially resolved mass spectrometry, as well as flow-dependent emission spectroscopy and mass spectrometry, suggest the analyte molecules to be formed in the cold plasma vicinity upon interaction with reactive species formed inside the hot plasma center. Spatial separation is maintained by concentrically expanding pressure waves, inducing a strong unidirectional diffusion. The accompanying rarefaction inside the plasma center can be compensated by a gas stream application. This replenishing results in a strong increase in emission brightness, in local reactive species concentration, and eventually in direct mass spectrometric sensitivity. To determine the analytical performance of the new technique, a comparison with an atmospheric pressure chemical ionization (APCI) source was conducted. Two kitchen herbs, namely, spearmint and basil, were analyzed without any sample pretreatment. The presented results demonstrate a considerably higher sensitivity of the presented laser-spark ionization technique. KW - Laser-spark KW - Laser induced plasma KW - Ambient mass spectrometry KW - Optical emission spectroscopy KW - Ionization PY - 2017 DO - https://doi.org/10.1021/acs.analchem.6b04178 SN - 0003-2700 SN - 1520-6882 VL - 89 IS - 6 SP - 3437 EP - 3444 PB - American Chemical Society CY - Washington, DC, USA AN - OPUS4-39474 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -