Local Thermodynamic Equilibrium in Laser-Induced Breakdown Spectroscopy: Beyond the McWhirter criterion

Cristoforetti, G.; Giacomo, A. De; Dell’Aglio, M.; Legnaioli, Stefano; Tognoni, E.; Palleschi, Vincenzo; Omenetto, N.

doi:10.1016/j.sab.2009.11.005

Cited by 538 publications

(251 citation statements)

References 37 publications

Supporting

Mentioning

233

Contrasting

Unclassified

Order By: Relevance

“…96 With regard to the articles cited, they can be divided into broad categories dealing with population distributions and deviations from equilibrium, [97][98][99][100][101][102][103][104][105][106][107][108][109][110] classification of diagnostic methods, 111,112 local and space-integrated intensity definitions, 113,114 ion-toneutral ratios and their diagnostic relevance, [115][116][117][118][119][120][121][122][123][124][125] line-to-continuum ratios, [126][127][128][129][130][131] scattering methods, [132][133][134][135] evaluation of electron number density and plasma temperature, including Stark broadening of H-lines, Stark broadening of non-hydrogenic transitions, influence of the instrumental profile, [199][200][201][202][203][204] calibration of...…”

Section: Local Thermodynamic Equilibrium Theoretical Equilibrium Expmentioning

confidence: 99%

“…T4.9). For a discussion of each of these parameters and their derivation, the reader is referred to Cristoforetti et al, 101 where the original references are reported. Calculations from literature data have shown that the diffusion length criterion is verified for copper, iron, and nickel, because the values obtained are much lower than the plasma dimensions, but cannot be fulfilled in the cases of hydrogen and oxygen.…”

Section: Expression Description Equation Numbermentioning

confidence: 99%

See 1 more Smart Citation

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

2010

View full text Add to dashboard Cite

Laser-induced breakdown spectroscopy (LIBS) has become a very popular analytical method in the last decade in view of some of its unique features such as applicability to any type of sample, practically no sample preparation, remote sensing capability, and speed of analysis. The technique has a remarkably wide applicability in many fields, and the number of applications is still growing. From an analytical point of view, the quantitative aspects of LIBS may be considered its Achilles' heel, first due to the complex nature of the laser–sample interaction processes, which depend upon both the laser characteristics and the sample material properties, and second due to the plasma–particle interaction processes, which are space and time dependent. Together, these may cause undesirable matrix effects. Ways of alleviating these problems rely upon the description of the plasma excitation-ionization processes through the use of classical equilibrium relations and therefore on the assumption that the laser-induced plasma is in local thermodynamic equilibrium (LTE). Even in this case, the transient nature of the plasma and its spatial inhomogeneity need to be considered and overcome in order to justify the theoretical assumptions made. This first article focuses on the basic diagnostics aspects and presents a review of the past and recent LIBS literature pertinent to this topic. Previous research on non-laser-based plasma literature, and the resulting knowledge, is also emphasized. The aim is, on one hand, to make the readers aware of such knowledge and on the other hand to trigger the interest of the LIBS community, as well as the larger analytical plasma community, in attempting some diagnostic approaches that have not yet been fully exploited in LIBS.

show abstract

Section: Local Thermodynamic Equilibrium Theoretical Equilibrium Expmentioning

confidence: 99%

Section: Expression Description Equation Numbermentioning

confidence: 99%

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

2010

View full text Add to dashboard Cite

show abstract

“…It is well known that typical LIBS plasmas generally do not exhibit LTE at very early stages of their expansion [42]; however, the measurements presented in this work were conducted at a delay time of 4 µs, which is considered sufficient for thermalization of the plasma to occur [35]. For any given plasma to be considered to be in LTE then the lower limit for the electron number density N e must satisfy Equation 5 [35,39,43]: …”

Section: Plasma Electron Density and Lte Considerationsmentioning

confidence: 99%

Hardness determination of bio-ceramics using Laser-Induced Breakdown Spectroscopy

Cowpe

Moorehead

Moser

et al. 2011

Spectrochimica Acta Part B: Atomic Spectroscopy

View full text Add to dashboard Cite

Abstract:Laser-Induced Breakdown Spectroscopy (LIBS) was applied to the analysis of bioceramic samples. The relationship between sample hardness and LIBS plasma properties was investigated, with comparison to conventional Vickers hardness measurements. The plasma excitation temperature T e was determined using the lineto-continuum ratio for the Si (I) 288.16 nm emission line; we have demonstrated a linear relationship between sample surface hardness and plasma temperature. Results indicate that hardness determination based on measurements of T e offers greater reproducibility than Vickers hardness measurements, under the conditions considered here. The validity of spectroscopic diagnostics based on LTE was confirmed.

show abstract

“…The total specific energy of the plasma, , is expressed in terms of the specific internal energy, , and kinetic energy as, Assuming that the expanding plasma plume follows the ideal gas law (under reduced pressure), the specific internal energy and pressure of plasma can be given by, where is the number density of the plasma, is the partial fraction of electrons in the ablated plume, is the temperature of the plasma, is the ionization energy of carbon at level , is the partial fraction of charged ions, and is the Boltzmann constant. Under our present process conditions the local thermodynamic equilibrium approximation (LTE) is reasonable as per McWhirter criterion [10]. When particles in the ablated plume reach LTE, the ionization state of the plasma can be calculated by the Saha-Eggert equation [11], where the degeneracy factor of an ionized atom at level , is the mass of an electron, and is the Planck constant.…”

Section: Plasma Expansion Dynamicsmentioning

confidence: 99%

Modeling of Plasma Expansion during Pulsed Electron Beam Ablation of Graphite

Ali

2017

MRS Advances

View full text Add to dashboard Cite

Pulsed electron beam ablation (PEBA) has proven to be a promising and powerful technique for the growth of high quality thin films. Pulsed electron beam film deposition consists of many physical processes including target material heating, target ablation, plasma plume expansion, and film growth on a substrate. Plasma plume expansion into a vacuum or an ambient gas is a fundamental issue in PEBA as the quality of thin films deposited onto the substrate depends on the composition, energy and density of particles ejected from the target. In the present study, gas-dynamics equations are solved to investigate plasma expansion induced by interaction of a nanosecond electron beam pulse (~100 ns) with a graphite target in an argon atmosphere at reduced pressure. The spatio-temporal profiles of the temperature, pressure, velocity, and density of the plasma plume are numerically simulated for a beam efficiency of 0.6 and accelerating voltage of 15 kV. The preliminary results show a rich variety of behaviors. The model is validated by comparing some of the obtained simulation results with experimental data available in the literature.

show abstract

Local Thermodynamic Equilibrium in Laser-Induced Breakdown Spectroscopy: Beyond the McWhirter criterion

Cited by 538 publications

References 37 publications

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma—Particle Interactions: Still-Challenging Issues within the Analytical Plasma Community

Hardness determination of bio-ceramics using Laser-Induced Breakdown Spectroscopy

Modeling of Plasma Expansion during Pulsed Electron Beam Ablation of Graphite

Contact Info

Product

Resources

About