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The equation of state for plasmas containing negative atomic and molecular ions (anions) is modeled. The model is based on 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–Hu¨ckel theory. In particular, the equation of state is obtained for plasmas containing the elements Ca, Cl, C, Si, N, and Ar. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules CaCl2, CaCl, Cl2, N2, C2, Si2 , CN, SiN, SiC, and their positive and negative ions. The model is applied to laserinduced plasmas (LIPs) by including the equation of state into a fluid dynamic numerical model based on the Navier–Stokes equations describing an expansion of LIP plumes into an ambient gas as a reactive viscous flow with radiative losses. In particular, the formation of anions Cl-, C-, Si-, Cl2, Si2, C2 , CN-, SiC-, and SiN- in LIPs is investigated in detail.

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.

Under the assumption of local thermal equilibrium, a numerical algorithm is proposed to find the equation of state for laser-induced plasmas (LIPs) in which chemical reactions are permitted in addition to ionization processes. The Coulomb interaction in plasma is accounted for by the Debye–Hückel method. The algorithm is used to calculate the equation of state for LIPs containing carbon, silicon, calcium, chlorine, nitrogen, and argon. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules N2, C2, Si2, CN, Cl2, SiN, SiC, CaCl, CaCl2 and their positive and (if existed) negative ions. The algorithm is incorporated into a fluid dynamic numerical model based on the Navier–Stokes equations describing an expansion of LIP plumes into an ambient gas. The dynamics of LIP plumes obtained by the ablation of SiC, CaCl2, solid silicon, or solid carbon in an ambient gas containing N2 and Ar is simulated to study formation of molecules and molecular ions. A particular attention is paid to formation of anions Cl−, Cl2−, Si2−, C2−, CN−, and SiN− in LIPs.

Two topics will be addressed: (1) calibration-free LIBS based on Monte Carlo spectral optimization and (2) insight into the possibility of simultaneous elemental and molecular analysis by LIBS. Both topics heavily rely on modeling of laser induced plasma and are closely connected to experiment. In Monte Carlo LIBS (MC LIBS), concentrations are found by fitting model-generated synthetic spectra to experimental spectra. The model of a static uniform isothermal plasma in local thermodynamic equilibrium is employed. Many configurations of plasma parameters and their corresponding spectra are simultaneously generated using a graphic processing unit (GPU). Using the GPU allows for the reduction of computational time down to several minutes for one experimental spectrum that presents the significant progress in comparison with earlier versions of MC LIBS. The method is tested by analyzing industrial oxides containing various concentrations of CaO, Fe2O3, MgO, and TiO2. The agreement within several percent between found and certified concentrations is achieved. Next, a newly developed collisional-dominated model of a laser induced plasma is introduced. The model includes the coupled Navier-Stokes, state, radiative transfer, and material transport equations and incorporates plasma chemistry through the equilibrium approach based on the use of atomic and molecular partition functions. Simple chemical systems are modeled including ablation of Si and C in N2 and Ar atmospheres.The model is used to study evolution of number densities of atomic and molecular species in the expanding plasma plume. The distribution is compared to experimental observations obtained by optical imaging and tomography. To further verify the model, dynamic plasma

A collisional-dominated model of a laser induced plasma will be presented which includes the coupled Navier-Stokes, state, radiative transfer, and material transport equations and incorporates plasma chemistry through the equilibrium approach based on the use of atomic and molecular partition functions. Simple chemical systems are modeled including ablation of Si, C, SiC, CaCl2 in N2 or Ar atmospheres with the formation of molecules N2, C2, Si2, CN, Cl2, SiN, SiC, CaCl, CaCl2 and their corresponding positive and negative ions1,2. The initial conditions are specially chosen to emulate the plasma state on the onset of expansion just after the laser pulse had ended.
The model is used to study evolution of number densities of atomic and molecular species in the expanding plasma plume. The distribution is compared to experimental observations obtained by optical imaging and tomography. The model and experiment serve to elucidate mechanisms of molecular formation in LIPs, the topic which has recently received much attention in the LIBS community.

A collisional-dominated model of a laser induced plasma will be presented which includes the coupled Navier-Stokes, state, radiative transfer, and material transport equations and incorporates plasma chemistry through the equilibrium approach based on the use of atomic and molecular partition functions. Simple chemical systems are modeled including ablation of Si, C, SiC, CaCl2 in N2 or Ar atmospheres with the formation of molecules N2, C2, Si2, CN, Cl2, SiN, SiC, CaCl, CaCl2 and their corresponding positive and negative ions. The model is used to study evolution of number densities of atomic and molecular species in the expanding plasma plume. The distribution is compared to experimental observations obtained by optical imaging and tomography. The model and experiment serve to elucidate mechanisms of molecular formation in LIPs, the topic which has recently received much attention in the LIBS community.

New developments in spectroscopic techniques for process control are, in general, driven by shortcomings of existing technology, for example, when sensitivity, selectivity, robustness, and so forth do not meet the demands. The perfect process analytical method would be based on a robust and easy to handle customized technique operating in real time, come without any need for calibration, that is, be an absolute method, have a professional support, and be compliant to increasing regulatory requirements. However, there are at least trends toward such an all-in-one device suitable for every purpose.
Small, low-field NMR systems equipped with permanent magnet technology have been developed and allow for quantitative analysis as on-line instruments in a production environment. Quantitative high-resolution on-line NMR spectroscopy contributes to process understanding in pilot plant and research environments.
Laser spectroscopy is a promising field in process analysis owing to its sensitivity and selectivity. Laser-induced breakdown spectroscopy LIBS is a promising field for direct in situ analysis and remote sensing. Applications of quantum-cascade lasers for process analytical applications are a promising technique. Techniques such as cavity ring-down spectroscopy (CRDS), tunable diode laser absorption spectroscopy (TDLAS), and photothermal techniques are briefly introduced.
Recent developments of new detectors have improved X-ray fluorescence analysis (XRF) for qualitative and quantitative on-line evaluation of the elementary composition of liquid or solid samples, regardless of whether compact or bulk material.
The chapter also introduces miscellaneous techniques such as ion mobility spectroscopy (IMS), microwave and dielectric spectroscopy, terahertz spectroscopy, ultrasonic acoustic spectroscopy, and other methods.

The stimulated emission (SE) in aluminum laser-induced plasma pumped in resonance with the 3s23p − 3s24s aluminum transition at 266.04 nm is investigated experimentally. It is shown that the population Inversion between the 3s23p and 3s24s states can be created by weak pumping at several microjoule to millijoule pulse energies and result in high gain. The intensity of the SE at 396.15 nm is related to the number density of Al Atoms via absorption measurements. It is found that the SE in forward and backward directions with respect to the pumping laser is different in terms of the line shape and intensity that is attributed to inhomogeneity in a gain coefficient across the plasma plume.