TY - JOUR A1 - Gornushkin, Igor B. A1 - Sennikov, P. A1 - Kornev, R. A1 - Ermakov, A. A1 - Shkrunin, V. T1 - Laser Induced Dielectric Breakdown for Chemical Vapor Deposition by Hydrogen Reduction of Volatile Boron Halides BCl3 and  BF3 N2 - A possibility of deposition from laser-induced plasma is investigated in search for an economic and simple method for obtaining isotopic compounds from enriched gaseous precursors although no isotopic compounds are used in this the proof-of-principle work. A breakdown in mixtures of BCl3 and BCl3 with hydrogen, argon, and methane are studied both theoretically and experimentally. Equilibrium chemistry calculations show the deposition of boron, boron carbide, and carbon is thermodynamically favorable in BCl3 systems and only carbon in BF3 systems. Dynamic calculation of expanding plasma is performed using fluid dynamics coupled with equilibrium chemistry. Condensed phases of boron, boron carbide, and graphite are predicted with maximum concentrations in peripheral zones of the plasma. In experiment, plasma is induced in mixtures BCl3, H2 + BCl3, H2 + Ar + BCl3, H2 + BCl3 + CH4, BF3, H2 + BF3, H2 + Ar + BF3, and H2 + Ar + BF3. The gases are analyzed before, during, and after laser irradiation by optical and mass spectrometry methods. The results show the composition of reaction products close to that predicted theoretically. The conversion of precursor gases BCl3 and BF3 into gaseous and condensed products is 100% for BCl3 and 80% for BF3. Solid deposits of up to 30 mg are obtained from all reaction mixtures. Due to technical reasons only FTIR characterization of the BCl3 + H2 + CH4 deposit is done. It points to presence of condensed boron and boron carbide predicted by the model. Overall, the calculations and preliminary experimental results imply the chemical vapor deposition with laser induced plasma is promising for conversion of gaseous enriched precursors into elemental isotopes and their isotopic compounds. KW - Boron halides KW - Chemical vapor deposition KW - Laser induced dielectric breakdown, Hydrogen reduction PY - 2020 DO - https://doi.org/10.1007/s11090-020-10096-w VL - 40 IS - 5 SP - 1145 EP - 1162 PB - Springer AN - OPUS4-50968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - model of laser induced plasma relevant to structuring and coating of titanium implants N2 - The presentation will give a brief overview of the processes occurring in laser-induced plasma and methods of modeling these processes. In particular, a chemical-hydrodynamic model will be considered, which is related to the modification of the surface of metallic titanium by laser pulses. The details and simplifications of this model, its shortcomings and the possibilities of their elimination will be discussed. This model is related to the structuring of the surface of dental implants with a laser and the deposition of an oxide film on it. T2 - THE 2-nd THEMATIC INTERNATIONAL SCIENTIFIC AUTUMN SCHOOL ON LASER MICRO- & NANOTHECHNOLOGIES: 2021 – BIOMEDICAL TECHNOLOGIES CY - St. Petersburg, Russia DA - 09.11.2021 KW - Laser ablation KW - Laser induced plasma deposition KW - Surface coating KW - Emission spectroscopy KW - Hydrodynamic model KW - Plasma chemistry PY - 2021 AN - OPUS4-53718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sennikov, P. A1 - Ermakov, A. A1 - Kornev, R. A1 - Gornushkin, Igor B. T1 - Laser induced dielectric breakdown in reactive mixture SiF4 + H2 N2 - Important chemical process of reduction of SiF4 by hydrogen is realized in laser induced dielectric breakdown (LIDB) plasma in a gas mixture of SiF4 and H2. The process may be an alternative to a method of Plasma enhanced chemical vapor deposition (PECVD) which is commonly used for production of pure and isotopically pure silicon films. The composition of laser induced plasma in gases SiF4, SiF4 + H2, SiF4 + H2 + Ar at atmospheric pressure is studied and compared to the composition of inductively coupled plasma (ICP) in the same gases but at reduced pressure of 3 Torr. The gaseous products of chemical reactions are inferred from optical emission spectroscopy (OES) and IR spectroscopy. The reaction products of silicon fluoride SiF and fluorosilanes SiHxFy (x, y = 1, 2, 3) in LIDB plasma are observed and confirmed by equilibrium chemistry calculations and simulations of plasma expansion dynamics using a fluid dynamic-chemical plasma model. It is further suggested that chemisorption of fluorinated species like SiFx (x = 1, 2) followed by the surface reaction with H-atoms lead to a formation of silicon-to‑silicon bonds on a substrate surface. A conclusion is drawn that energetic laser induced plasma can prove efficient for one-step PECVD by hydrogen reduction of SiF4. KW - Silicon halides KW - Chemical vapor deposition KW - Laser induced dielectric breakdown KW - Hydrogen reduction PY - 2021 DO - https://doi.org/10.1016/j.sab.2021.106099 VL - 179 SP - 106099 PB - Elsevier B.V. AN - OPUS4-53583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Modeling Equilibrium Chemistry in Laser Induced Plasmas and Plasma Chemical Reactors N2 - A brief introduction will be given on modeling chemical reactions in laser induced plasmas using stoichiometric and non-stoichiometric approaches. Several applications will be considered, which can benefit from such modeling. Those include plasma enhanced chemical vapor deposition (PECVD), surface modification and surface coating, and molecular analysis by LIBS. Each application will be illustrated by simulations of relevant chemical systems. For PECVD, chemical systems are BCl3/H2/Ar, BF3/H2/Ar, BCl3/BF3, Mo/BF3/H2; for surface modification/coating it is Ti/air; for molecular LIBS they are CaCO3/Ar, Ca(OH)2/Ar, and CaCl2/Ar. Advantages and shortcomings of equilibrium chemical hydrodynamic models of laser induced plasmas will be discussed. T2 - Moscow University, Department of Chemistry CY - Moscow, Russia DA - 26.10.2021 KW - Laser ablation KW - Laser induced plasma deposition KW - Emission spectroscopy KW - Surface coating KW - Hydrodynamic model KW - Plasma chemistry PY - 2021 AN - OPUS4-53629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Sennikov, P. A1 - Kornev, R. T1 - Laser induced gas breakdown in reactive mixtures N2 - Plasma-chemical approach is used for synthesis of various gaseous, liquid, and solid substances since 1960th. Nowadays, the method of plasma enhanced chemical vapor deposition (PECVD) is used for production of thin films, protective coatings, carbon-based nanostructures, high purity isotopic materials, biomaterials, and other products. Plasma for PECVD is typically created in various electrical discharges, e.g. DC and AC glow discharges or discharges operated at audio (10-20 kHz), radio (13.56 MHz), and microwave (2.45 GHz) frequencies. Plasma induced by a laser, a laser induced plasma (LIP), is rarely used to deposit materials from the gas phase as in PECVD. This work is aimed at reviving interest to this latter technology and showing its efficiency and potential. We run several pilot experiments. First, LIP is excited in BCl3 or BF3 plus H2 or CH4 to evaluate the efficiency of deposition of solid boron and boron carbide, the materials, which are largely used for refractory coatings. Second, we investigate a possibility of synthesis of fluorochlorosilanes SiFxCl4-x (x = 1, 2, 3) by LIP induced in SiF4 + SiCl4 gas mixtures. Using fluorochlorosilanes with different combinations of F and Cl in the SiFxCly molecule may add flexibility in processes of silicon deposition and etching. Third, LIP is excited in reactive mixture MoF6+H2+BF3 or on a Mo target ablated into H2/BF3 atmosphere. The goal is obtaining superhard molybdenum borides MoB, Mo2B, or MoB2. The gases used and solid deposits are analyzed by optical emission spectroscopy (OES), IR and mass spectrometry (MS). We also model the plasma and perform static equilibrium chemistry calculations to see if the desired reaction products are thermodynamically favorable. Dynamic calculations of the expanding plasma plume are performed using a hydrodynamic code combined with the open source chemical software. T2 - SciX 2021, The Federation of Analytical Chemistry and Spectroscopy Societies (FACSS) CY - Providence, RI, USA DA - September 26, 2021 KW - Laser ablation KW - Laser induced plasma deposition KW - Emission spectroscopy KW - Surface coating KW - Plasma chemistry KW - Hydrodynamic model PY - 2021 AN - OPUS4-53560 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Kornev, R. A. A1 - Veiko, V. P. T1 - Molecule formation in reactive LIBS plasmas: model and experiment N2 - Formation and detection of molecules in laser induced plasmas (LIP) is a hot topic. In analytical plasmas like LIBS, the detection of molecules is important for identification of geological and other materials, analysis of isotopes and difficult elements (Cl, F, etc.) via molecular emission. In chemical plasmas, like PECVD (plasma enhanced chemical vapor deposition) or PLD (pulsed laser deposition), molecules formed in the plasma determine a composition and a thickness of deposits. Similarly, molecules play an important role in microstructuring and oxidizing metal surfaces by laser ablation. It is unfortunate that different communities, which utilize plasma methods and seek for solutions of similar problems, do not strongly overlap, and do not fully use knowledge accumulated by each other. In this presentation, mechanisms of formation of molecules will be analyzed on the example of LIPs used for chemical vapor deposition and metal microstructuring. Theoretical analysis includes equilibrium chemistry calculations combined with plasma hydrodynamics. First, LIP excited in a gas mixture of BCl3 or BF3 with H2 or CH4 will be analyzed; this chemical system is used for obtaining deposits of refractory solid boron and boron carbide. Second, a breakdown in the SiF4 + SiCl4 gas mixtures will be described; this method allows synthesis of fluorochlorosilanes SiFxCl4-x (x = 1, 2, 3), the good etching agents (Figure). Third, solid ablation of Mo in BF3+H2 and Ti in air will be considered aimed at obtaining deposits of high hardness MoxBy and films of TixOy on textured Ti surfaces, correspondingly. In experiment, reaction gases before and after laser illumination, and solid deposits are analyzed by optical emission spectroscopy (OES), IR and mass spectrometry (MS), SEM, X-ray, and AFM. It will be shown that the hydrodynamic-chemical model adequately predicts the composition of LIPs, zones of molecular formation, dependence on reactant stoichiometry, plasma temperature and pressure. T2 - Euro-Mediterranean Symposium on Laser-Induced Breakdown Spectroscopy CY - Gijon, Spain DA - 29.11.2021 KW - Laser induced plasma KW - Plasma chemistry KW - Molecules formation KW - Plasma enhanced chemical deposition PY - 2021 AN - OPUS4-53850 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Kornev, Roman A1 - Kornev, A. R. A1 - Ermakov, A. A. T1 - Laser dielectric breakdown as a novel method for producing molybdenum borides N2 - Superhard materials with a Vickers hardness in the range of 30-40 GPa are of great interest, both from a fundamental and a practical viewpoints, since they have outstanding mechanical, thermal and chemical properties. Molybdenum borides belong to this group of materials. A review of publications on synthesis of molybdenum boride indicates a) great interest in this superhard material and b) the need for new effective methods of its synthesis, especially in a nanocrystalline form. Very promising are the plasma-chemical methods based on laser induced breakdown. The breakdown can be created either in reactive gases containing volatile compounds of boron and molybdenum or on solid samples. For gas breakdown, molybdenum hexafluoride MoF6 and boron trifluoride BF3 were used in the mixture with hydrogen and argon; for solid breakdown, the pure molybdenum sample was ablated into the mixture of H2 and BF3. The plasma-chemical synthesis of MoxBy structures was carried out in the reactor shown in Figure. Laser breakdown was created by a pulsed Nd: YAG laser operating at 1064 nm with a 15 ns pulse duration, 5 Hz repetition rate, and 800 mJ pulse energy. The laser was focused by a 5 cm focal length lens to produce 26 J/cm3 energy density in the focal point. The ratios H2:BF3: MoF6 = 5:2:1 and H2:BF3 = 3:1 were used in a pressure range 30 - 760 Torr. After ablation in the mixture H2 + BF3 + MoF6, the deposit contained an amorphous phase with a small impurity of crystalline molybdenum and no boride phase. After ablation of metallic Mo into H2 + BF3, the main phase was MoB2 in the form of nano dispersed powder with an average grain size of 100 nm. The degree of conversion of boron trifluoride and the yield of molybdenum boride were studied as a function of pressure. It was established that 30 Torr is optimal for the formation of MoB2. This work was supported by the Russian Science Foundation grant No. 20-13-00035. T2 - Euro-Mediterranean Symposium on Laser-Induced Breakdown Spectroscopy CY - Online meeting DA - 29.11.2021 KW - Plasma enhanced chemical deposition KW - Laser induced plasma KW - Plasma chemistry KW - Molybdenum boride PY - 2021 AN - OPUS4-53901 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Plasma fundamentals and diagnostics N2 - This course will provide an introduction to plasma diagnostic techniques. The major focus of the course will be on the discussions of the practical procedures as well as the underlying physical principles for the measurements of plasma fundamental characteristics (e.g., temperatures, thermodynamic properties, and electron number density). Particular emphasis will be placed on inductively coupled plasma–atomic emission spectrometry, but other analytical plasmas will also be used as examples when appropriate. Selected examples on how one can manipulate the operating conditions of the plasma source, based on the results of plasma diagnostic measurements, to improve its performance used for spectrochemical analysis will also be covered. Topics to be covered include thermal equilibrium, line profiles, temperatures, electron densities, excitation processes, microreactions, pump and probe diagnostics, tomography, temporal and spatial resolution. Basics of plasma computer modeling will be presented. T2 - 03.-06. September 2018, 13 Symposium "Massenspektrometrische Verfahren der Elementspurenanalyze", BAM, Berlin, Adlershof CY - BAM, Berlin, Adlershof, Germany DA - 03.09.2018 KW - Thermal equilibrium KW - Plasma processes KW - Electron number density KW - Temperatures KW - Emission line profiles KW - Spatial information KW - Plasma modeling PY - 2018 AN - OPUS4-46108 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Shabanov, Sergej V. T1 - Dynamical chemical model of laser induced plasma N2 - Laser induced plasma (LIP) is a highly dynamic, short living event which presents significant difficulty for both diagnostics and modeling. The former requires precise spatially- and time-resolved measurements on a micron-nanosecond scale while the latter needs numerous descriptive parameters; many of them can only be obtained from experiment. Diagnostics and modeling should always complement each other for obtaining a truthful picture of LIP. In this presentation, a newly developed collisional-dominated model will be presented. The model is based on the coupled Navier-Stokes, state, radiative transfer, material transport, and chemical equations. The model incorporates plasma chemistry through the equilibrium approach that relies on atomic and molecular partition functions. Several chemical systems are modeled including Si-C-Cl-N and B-H-Cl systems. The model is used to study the equilibrium states of the systems as functions of the concentrations of plasma species and plasma temperature. The model also predicts the evolution of number densities of atomic and molecular species in the expanding plasma plume. T2 - 18.09.2018, 9th International Conference on PLASMA PHYSICS AND PLASMA TECHNOLOGY (PPPT‐9) CY - Minsk, Belorussia DA - 17.09.2018 KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics PY - 2018 AN - OPUS4-46111 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Shabanov, Sergej V. T1 - Chemistry in laser‑induced plasmas at local thermodynamic equilibrium N2 - The equation of state for plasmas containing negative and positive ions of elements and molecules formed by these elements is modeled under the assumption that all ionization processes and chemical reactions are at local thermal equilibrium and the Coulomb interaction in the plasma is described by the Debye–Hückel theory. The hierarchy problem for constants of molecular reactions is resolved by using three different algorithms for high, medium, and low temperatures: the contraction principle, the Newton–Raphson method, and a scaled Newton–Raphson method, respectively. These algorithms are shown to have overlapping temperature ranges in which they are stable. The latter allows one to use the developed method for calculating the equation of state in combination with numerical solvers of Navier–Stokes equations to simulate laser-induced Plasmas initiated in an atmosphere and to study formation of molecules and their ions in such plasmas. The method is applicable to a general chemical network. It is illustrated with examples of Ca–Cl and C–Si–N laser-induced plasmas. KW - Plasma KW - LIBS KW - Plasma modeling PY - 2018 DO - https://doi.org/10.1007/s00339-018-2129-9 SN - 1432-0630 SN - 0947-8396 VL - 124 IS - 10 SP - 716, 1 EP - 21 PB - Springer AN - OPUS4-46112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Dell’Aglio, M. A1 - Motto-Ros, V. A1 - Pelascini, F. A1 - De Giacomo, A. T1 - Investigation on the material in the plasma phase by high temporally and spectrally resolved emission imaging during Pulsed Laser Ablation (PLAL) in Liquid for NPs production and consequent considerations on NPs formation N2 - In this paper experimental temperature and density maps of the laser induced plasma in water during Pulsed Laser ablation in Liquid (PLAL) for the production of metallic nanoparticles (NPs) has been determined. A detection system based on the simultaneous acquisition of two emission images at 515 and 410 nm has been constructed and the obtained images have been processed simultaneously by imaging software. The results of the data analysis show a variation of the temperature between 4000 and 7000 K over the plasma volume. Moreover, by the study of the temperature distribution and of the number densities along the plasma expansion axis it is possible to observe the condensation zone of the plasma where NPs can be formed. Finally, the time associated to the electron processes is estimated and the plasma charging effect on NPs is demonstrated. The set of observations retrieved from these experiments suggests the importance of the plasma phase for the growth of NPs and the necessity of considering the spatial distribution of plasma parameters for the understanding of one of the most important issues of the PLAL process, that is the source of solid material in the plasma phase. KW - LIBS KW - Laser induced plasma KW - Plasma modeling KW - Plasma diagnostics KW - Nanoparticle formation PY - 2019 DO - https://doi.org/10.1088/1361-6595/ab369b VL - 28 IS - 8 SP - Article Number: 085017 PB - IOP Publishing AN - OPUS4-48753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huan, Y. A1 - Gojani, Ardian A1 - Gornushkin, Igor B. A1 - Wang, X. A1 - Liu, D. A1 - Rong, M. T1 - Dynamics of laser-induced plasma splitting N2 - The dynamics of laser-induced plasma plume splitting is investigated using spatiotemporal plasma imaging and spectrometry in this paper. Plasma plume splitting into fast and slow components is clearly observed using plasma optical emission as time evolves. The spatial resolved plasma spectra are used to investigate the plasma species distribution, which reveals that the charged copper ions, which radiate at wavelength range 485 nm - 504 nm, are merely present in the fast component. In order to further interpret the mechanism, the pressure-dependent and laser energy-dependent plume splitting are analyzed. Based on the results, the charge separation field is proposed to explain this phenomenon. This work can be of importance for such areas as laser induced breakdown spectroscopy, laser-induced ion source formation, pulse laser deposition, film growth, and nanoscale synthesis. KW - Spectroscopy KW - Laser induced plasma KW - Splitting KW - Imaging PY - 2020 DO - https://doi.org/10.1016/j.optlaseng.2019.105832 SN - 0143-8166 VL - 124 SP - 1 EP - 5 PB - Elsevier CY - Amsterdam AN - OPUS4-48746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Palásti, David J. A1 - Veres, M. A1 - Rigó, I. A1 - Geretovszky, Z. A1 - Kovács-Széles, É. A1 - Gojani, Ardian A1 - Galbács, Gábor T1 - Optimization and detailed spectroscopic characterization of an improved SH-LIBS setup N2 - The spatial heterodyne detection principle has a great potential in spectroscopy. It has an optical setup similar to that of a Michelson interferometer, with the mirrors replaced by diffraction gratings positioned at fixed, equal distances from the beamsplitter and are slightly tilted. The resulting interference pattern is recorded by a digital camera and the spectrum is recovered by using Fourier transformation. Although SHS was initially developed for astronomical and satellite-based atmospheric measurements, but in recent years it has been started to be applied in other branches of spectroscopy too. Recently the area of laser-induced breakdown spectroscopy (LIBS) has also discovered the potential of SHS. The main appeal of SHS detection in LIBS includes the compactness and robustness of the setup (in view of field applications) and the flexibility to optimize the setup for either high sensitivity or for high resolution, which can be benficially exploited in applications like stand-off measurements, quantitative analysis with isotope resolution, etc. In the present work, we have improved and further optimized our initial LIBS-SHS setup described in a previous conference. By using optical simulations, we have modelled the light transmission efficiency, instrumental function and imaging properties of the system. We significantly improved and automated the spectral and image data processing sequence. The optimizations carried out resulted in an improved spectral resolution and repeatability, a lower spectral background and the elimination of the central line artifact originating from the Fourier transformation procedure. A detailed characterization of the LIBS spectroscopy performance (e.g. resolution, spectral coverage, tuning range, linearity, etc.), including a comparison with that of a LIBS setup based on a conventional dispersion CCD spectrometer was also performed. T2 - European Winter Conference on Plasma Spectrochemistry (EWSPS-2019) CY - Pau, France DA - 03.02.2019 KW - SHS KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Spatial heterodyne spectrometer PY - 2019 AN - OPUS4-48047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yuan, Huan A1 - Gojani, Ardian A1 - Gornushkin, Igor B. A1 - Wang, X. T1 - Investigation of laser-induced plasma at varying pressure and laser focusing N2 - Expansion dynamics of laser-induced plasma is studied for different focal positions of the ablation laser in the pressure range 10-2 - 105 Pa of the ambient air. The experimental results indicate that both the parameters significantly affect the plasma size, shape, intensity, reproducibility, and distance from the target surface. At pressures above 10 Pa, the plasma plume is confined by the ambient gas; the plumes are more compact and travel shorter distances from the target as compared to the analogous plume characteristics at pressures below 10 Pa. The pulse-to-pulse reproducibility of the integral emission intensity of the plasma is also different for different focal positions and pressures. It is found that the focal positions -1 cm and -2 cm below the target surface yield the most reproducible and intense emission signals as measured at the 600 ns delay time with the 100 ns gate. The information obtained can be of importance for pulsed laser deposition, laser welding, and analytical spectroscopy at reduced pressures. In general, a correct choice of the focal position and pressure of an ambient gas is very important for obtaining the strongest plasma emission, good reproducibility, and desired plasma plume shape. KW - Laser-induced plasma KW - Plasma expansion KW - Imaging PY - 2018 DO - https://doi.org/10.1016/j.sab.2018.10.005 SN - 0584-8547 VL - 150 SP - 33 EP - 37 PB - Elsevier AN - OPUS4-46207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Kazakov, Alexander Ya. T1 - Model of stimulated emission in aluminum laser-induced plasma produced by resonance pumping N2 - Stimulated emission observed experimentally in aluminum laser induced plasma is modeled via a kinetic approach. The simulated emission at several cascade transitions is created by a pump laser guided through the plasma at several microseconds after its creation and tuned in resonance with the strong transition at 266 nm. A two-dimensional space-time collisional radiative plasma model explains the creation of the population inversion and lasing at wavelengths 2.1 μm and 396.1 nm. The population inversion for lasing at 2.1 μm is created by depopulation of the ground state and population of the upper state via absorption of resonant radiation at 266 nm. The population inversion for lasing at 396.1 nm occurs during the laser pulse via the decay of the population of the pumped upper state to the lasing state via cascade transitions driven optically and by collisions. The model predicts that the population inversion and corresponding gain may reach high values even at moderate pump energies of several μJ per pulse. The efficiency of lasing at 2.1 μm and 396.1 nm is estimated to be on the order of a percent of laser pump energy. The polarization effect that the pump radiation at 266 nm imposes on the stimulated emission at 396.1 nm is discussed. The calculated results are favorably compared to experiment. T2 - FLAMN, June 30- July 4 2019 CY - St. Petersburg, Russia DA - 30.06.2019 KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics PY - 2019 AN - OPUS4-48598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gojani, Ardian A1 - Palásti, David J. A1 - Paul, Andrea A1 - Galbács, G. A1 - Gornushkin, Igor B. T1 - Analysis and classification of liquid samples by spatial heterodyne spectroscopy N2 - Spatial heterodyne spectroscopy (SHS) is used for quantitative analysis and classification of liquid samples. SHS is a version of a Michelson interferometer with no moving parts and with diffraction gratings in place of mirrors. The instrument converts frequency-resolved information into spatially resolved one and records it in the form of interferograms. The back-extraction of spectral information is done by the Fast Fourier transform. A SHS instrument is constructed with the resolving power 5000 and spectral range 522 - 593 nm. Two original technical solutions are used as compared to previous SHS instruments: the use of a high frequency diode pumped solid state (DPSS) laser for excitation of Raman spectra and a microscope-based collection system. Raman spectra are excited at 532 nm at the repetition rate 80 kHz. Raman shifts between 330 cm-1 and 1600 cm-1 are measured. A new application of SHS is demonstrated: for the first time it is used for quantitative Raman analysis to determine concentrations of cyclohexane in isopropanol and glycerol in water. Two calibration strategies are employed: univariate based on the construction of a calibration plot and multivariate based on partial least square regression (PLSR). The detection limits for both cyclohexane in isopropanol and glycerol in water are at a 0.5 mass% level. In addition to the Raman-SHS chemical analysis, classification of industrial oils (biodiesel, poly(1-decene), gasoline, heavy oil IFO380, polybutenes, and lubricant) is performed using their Raman-fluorescence spectra and principal component analysis (PCA). The oils are easily discriminated as they show distinct non-overlapping patterns in the space of principal components. KW - Spectroscopy KW - Atomic KW - Laser induced breakdown KW - Lasers PY - 2019 DO - https://doi.org/10.1177/0003702819863847 SN - 1943-3530 VL - 73 IS - 12 SP - 1409 EP - 1419 PB - Sage AN - OPUS4-48599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Calibration-free LIBS of steel samples N2 - An improved algorithm for calibration-free laser induced breakdown spectroscopy (CF LIBS) is presented which includes several novel features in comparison with previously proposed similar algorithms. In particular, it allows using spectral lines with arbitrary optical thickness for the construction of Saha-Boltzmann plots, retrieves the absorption path length (plasma diameter) directly from a spectrum, replaces the Lorentzian line profile function by the Voigt function, and allows for self-absorption correction using pre-calculated and tabulated data rather than approximating functions. The tabulated data embody the solutions of the radiative transfer equation for numerous combinations of optical thicknesses and line widths. The algorithm is used to analyze 100 low alloy steel spectra. T2 - 20.06.2019 LTB workshop on LIBS analysis of steel CY - Berlin, LTB, Germany DA - 20.06.2019 KW - Laser induced plasma KW - LIBS KW - Plasma modeling KW - Plasma diagnostics KW - Chemical reactors PY - 2019 AN - OPUS4-48600 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Laser induced Plasma: Modeling and diagnostics N2 - Laser-induced plasmas are widely used in many areas of science and technology; examples include spectrochemical analysis, thin film deposition, material processing, and even jet propulsion. Several topics will be addressed. First, general phenomenology of laser-induced plasmas will be discussed. Then, a chemical model will be presented based on a coupled solution of Navier-Stokes, state, radiative transfer, material transport, and chemical (Guldberg-Waage) equations. Results of computer simulations for several chemical systems will be shown and compared to experimental observations obtained by optical imaging, spectroscopy, and tomography. The latter diagnostic tools will also be briefly discussed. T2 - Lecture at the Dept of Chemistry of Czeged University (Hungary) on 31.05.2019 CY - Czeged, Hungary DA - 31.05.2019 KW - Plasma KW - LIBS KW - Plasma modeling PY - 2019 AN - OPUS4-48188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. T1 - Several approaches to calibration-free LIBS: Advantages and pitfalls N2 - An overview of calibration-free laser induced breakdown spectroscopy (CF LIBS) methods is presented. Advantages and pitfalls of these methods are critically discussed. T2 - Workshop of the Spectrochemical Working Committee (SWC) of the Hungarian Academy of Sciences CY - Budapest, Hungary DA - 05.06.2019 KW - Calibration-free LIBS KW - CF LIBS algorithms PY - 2019 AN - OPUS4-48189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Völker, Tobias A1 - Kazakov, Alexander Ya. T1 - Improved algorithm for calibration-free laser induced breakdown spectroscopy N2 - An improved algorithm for calibration-free laser induced breakdown spectroscopy (CF LIBS) will be presented which includes several novel features in comparison with previously proposed similar algorithms. In particular, it allows using spectral lines with arbitrary optical thickness for the construction of Saha-Boltzmann plots, retrieves the absorption path length (plasma diameter) directly from a spectrum, replaces the Lorentzian line profile function by the Voigt function, and allows for self-absorption correction using pre-calculated and tabulated data rather than approximating functions. The tabulated data embody the solutions of the radiative transfer equation for numerous combinations of optical thicknesses and line widths. The algorithm is thoroughly verified using synthetic spectra. T2 - LIBS 2018 at SciX 2018 CY - Atlanta, GA, USA DA - 21.10.2018 KW - Plasma diagnostics KW - Laser induced plasma KW - LIBS KW - Plasma modeling PY - 2018 AN - OPUS4-46930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Pignatelli, Giuseppe A1 - Straße, Anne T1 - Optical detection of defects during laser metal deposition: Simulations and experiment N2 - Laser metal deposition is a rapidly evolving method for additive manufacturing that combines high performance and simplified production routine. Quality of production depends on instrumental design and operational parameters that require constant control during the process. In this work, feasibility of using optical spectroscopy as a control method is studied via modeling and experimentally. A simplified thermal model is developed based on the time-dependent diffusion-conduction heat equation and geometrical light collection into detection optics. Intense light emitted by a laser-heated spot moving across a sample surface is collected and processed to yield the temperature and other temperature-related parameters. In a presence of surface defects the temperature field is distorted in a specific manner that depends on a shape and size of the defect. Optical signals produced by such the distorted temperature fields are simulated and verified experimentally using a 3D metal printer and a sample with artificially carved defects. Three quantities are tested as possible metrics for process monitoring: temperature, integral intensity, and correlation coefficient. The shapes of the simulated signals qualitatively agree with the experimental signals; this allows a cautious inference that optical spectroscopy is capable of detecting a defect and, possibly, predicting its character, e.g. inner or protruding. KW - Additive manufacturing KW - Laser metal deposition (LMD) KW - Thermal model KW - Optical sensor KW - Process control PY - 2021 DO - https://doi.org/10.1016/j.apsusc.2021.151214 SN - 0169-4332 VL - 570 SP - 1 EP - 13 PB - Elsevier CY - Amsterdam AN - OPUS4-53292 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gornushkin, Igor B. A1 - Pignatelli, Giuseppe A1 - Straße, Anne T1 - Optical Detection of Defects during Laser Metal Deposition - Simulations and Experiment N2 - Laser metal deposition is a rapidly evolving method for additive manufacturing that combines high performance and simplified production routine. Quality of production depends on instrumental design and operational parameters that require constant control during the process. In this work, feasibility of using optical spectroscopy as a control method is studied via modeling and experimentally. A simplified thermal model is developed based on the time-dependent diffusion-conduction heat equation and geometrical light collection into detection optics. Intense light emitted by a laser-heated spot moving across a sample surface is collected and processed to yield the temperature and other temperature-related parameters. In a presence of surface defects the temperature field is distorted in a specific manner that depends on a shape and size of the defect. Optical signals produced by such the distorted temperature fields are simulated and verified experimentally using a 3D metal printer and a sample with artificially carved defects. Three quantities are tested as possible metrics for process monitoring: temperature, integral intensity, and correlation coefficient. The shapes of the simulated signals qualitatively agree with the experimental signals; this allows a cautious inference that optical spectroscopy is capable of detecting a defect and, possibly, predicting its character, e.g. inner or protruding. T2 - 28th International Conference on Advanced Laser Technologies CY - Online meeting DA - 06.09.2021 KW - Additive manufacturing KW - Laser metal deposition KW - Optical sensor KW - Optical emission spectroscopy KW - Process control PY - 2021 AN - OPUS4-53246 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -