Investigation on self-absorption at reduced air pressure in quantitative analysis using laser-induced breakdown spectroscopy

Hao, Zhongqi; Liu, L.; Shen, Mohan; Yang, Xin; Li, K. H.; Guo, Lian Bo; Li, X. Y.; Lu, Yong Feng; Zeng, Xianlin

doi:10.1364/oe.24.026521

Cited by 54 publications

(16 citation statements)

References 17 publications

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“…The Lorentzian shape could be explained by Stark-broadening as a result of high electron densities in the plasma initiation phase. While it is, in general, assumed that spectral lines emitted by vacuum plasmas are less affected by self-absorption [100] and Stark broadening [96] due to the lower density of the plasma species, the lowest investigated pressure in the study by Dreyer et al [96] is about 140 Pa (1 Torr). For even lower pressures the plasma life time is reduced and Stark-broadened emission from the early plasma due to an initially high electron density can likely dominate the time-integrated signal.…”

Section: Instrumental Response To Spatial Regions Of the Plasmamentioning

confidence: 99%

Detecting sulfur on the Moon: The potential of vacuum ultraviolet laser-induced breakdown spectroscopy

Kubitza

Schröder

Dietz

et al. 2020

Spectrochimica Acta Part B: Atomic Spectroscopy

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This thesis investigates the application of laser-induced breakdown spectroscopy (LIBS) with detection in the vacuum ultraviolet (VUV) spectral range for in-situ space exploration. LIBS is a type of optical emission spectroscopy (OES). For LIBS, a pulsed laser is tightly focused onto the sample, thereby ablating material and exciting a luminous plasma. The atoms and ions contained in the plasma radiate light of characteristic wavelengths, which can be analysed with spectrometers like in other types of OES. The spectral analysis allows to identify the chemical elements in the plasma, which are assumed to be representative for the elements in the sample. With LIBS, in principle all elements can be detected. However, especially the non-metal elements are challenging to detect because their strongest lines are located in the VUV spectral range, i.e. below 200 nm, which is often not investigated. Detection in this range brings its own challenges, since large parts of the radiation spectrum are absorbed by the atmosphere surrounding the sample. On celestial bodies without an atmosphere, such as the Moon, the ambient conditions are well suited for VUV-LIBS analyses. In such a scenario, a better detectability for the otherwise challenging elements C, Cl, H, N, O, P and S is expected compared to LIBS in the usually employed detection range above 200 nm.Motivated by the recent ambitions of the national space agencies to return to the Moon and to potentially set up a permanent moon base in the near future, I investigated the potential of VUV-LIBS in a lunar context. For this project, a dedicated set-up for VUV-LIBS was designed and built at Institut für Optische Sensorsysteme of Deutsches Zentrum für Luft-und Raumfahrt (DLR-OS) in Berlin-Adlershof. After an initial characterization including a relative spectral sensitivity estimate, chemically simple samples have been studied in order to identify emission lines that are typically detectable with this set-up. From these measurements, emission lines from Al,

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Section: Instrumental Response To Spatial Regions Of the Plasmamentioning

confidence: 99%

Detecting sulfur on the Moon: The potential of vacuum ultraviolet laser-induced breakdown spectroscopy

Kubitza

Schröder

Dietz

et al. 2020

Spectrochimica Acta Part B: Atomic Spectroscopy

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“…However, their mathematical complexity limited the application. There are many more studies on how to suppress the effect of self-absorption in LIBS which cannot be mentioned one by one in this paper [29][30][31][32][33][34] , but one can nd the references that are mentioned in this paper.…”

Section: Introductionmentioning

confidence: 99%

Simple Defocus Laser Irradiation to Suppress Self-Absorption in Laser-Induced Breakdown Spectroscopy (LIBS)

Marpaung

Harefa

Pardede

et al. 2021

Preprint

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This study introduces a novel and extremely simple way for suppressing the self-absorption effect in laser-induced breakdown spectroscopy (LIBS) by utilizing a defocusing laser irradiation technique. It is claimed that defocusing laser irradiation produces more uniform laser plasma due to lower fluence than tight focus laser irradiation, hence greatly lowering the effect of self-absorption in the laser plasma. KCl and NaCl pellet samples were used to demonstrate this achievement. When the defocus position is adjusted to – 6 mm for KCl and NaCl samples, the self-reversal emission lines K I 766.4 nm, K I 769.9 nm, Na I 588.9 nm, and Na I 589.5 nm vanish. Meanwhile, the FWHM values of K I 766.4 and K I 769.9 nm are 0.29 nm and 0.23 nm, respectively, during -6 mm defocus laser irradiation, as opposed to 1.24 nm and 0.86 nm, under tight focus laser irradiation. Additionally, this work demonstrates that when the laser energy is changed in between 10 to 50 mJ, no self-reversal emission occurs when -6 mm defocus laser irradiation is applied. Finally, a linear calibration curve is generated using KCl at a high concentration ranging between K concentration from 16.6–29%. This simple change of defocus laser irradiation will undoubtedly contribute to the suppression of the self-absorption phenomenon, which disrupts LIBS analytical results.

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“…In addition to these experimental approaches, certain researchers used mathematical models to minimize the self-absorption effect 15 – 17 . Because of the importance of the self-absorption effect relative to the linearity of the calibration line in LIBS, many studies have also been proposed and cannot all be listed in this manuscript, but they can be considered as excellent references for the study of self-absorption 18 – 25 .…”

Section: Introductionmentioning

confidence: 99%

Suppression of self-absorption in laser-induced breakdown spectroscopy using a double pulse orthogonal configuration to create vacuum-like conditions in atmospheric air pressure

Karnadi

Pardede

Tanra

et al. 2020

Sci Rep

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Self-absorption, which is known to severely disturb identification of the emission peak intensity in emission-based spectroscopy, was first studied using ordinary single pulse laser-induced breakdown spectroscopy (LIBS). It was found that severe self-absorption, with an evident self-reversal, occurs in the resonance emission lines of high concentration Na, K, and Al, and thus it is impossible to obtain the linear calibration curve required for quantitative analysis. To overcome this problem, we introduce a double pulse orthogonal technique in which the first laser is fired in a parallel orientation at a varied distance of 2–6 mm from the sample surface. It is well known that the strong shock wave generated by this laser irradiation temporarily creates a vacuum-like condition immediately in front of the sample surface. This action is followed by a second laser irradiation oriented perpendicular to the sample surface. The sample ablated by the second laser irradiation expands following the shockwave excitation process in the vacuum-like air atmosphere created by the first laser. The obtained spectra of the resonance emission lines of high concentration Na, K, and Al are free from the self-reversal and weakly affected by the self-absorption effect. A linear calibration curve that intercepts near zero point for K element over a wide concentration range is also demonstrated in this study. This simple modification is considered notably helpful in overcoming the self-absorption that occurs in ordinary single pulse atmospheric pressure LIBS.

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Investigation on self-absorption at reduced air pressure in quantitative analysis using laser-induced breakdown spectroscopy

Cited by 54 publications

References 17 publications

Detecting sulfur on the Moon: The potential of vacuum ultraviolet laser-induced breakdown spectroscopy

Detecting sulfur on the Moon: The potential of vacuum ultraviolet laser-induced breakdown spectroscopy

Simple Defocus Laser Irradiation to Suppress Self-Absorption in Laser-Induced Breakdown Spectroscopy (LIBS)

Suppression of self-absorption in laser-induced breakdown spectroscopy using a double pulse orthogonal configuration to create vacuum-like conditions in atmospheric air pressure

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