Diagnostics of silicon plasmas produced by visible nanosecond laser ablation

Milán, M.; Laserna, J.J.

doi:10.1016/s0584-8547(01)00158-6

Cited by 133 publications

(75 citation statements)

References 40 publications

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“…[17][18][19] In general, both Doppler and Stark broadening can contribute to spectral line broadening. However, the effect due to Doppler broadening (;0.12A Ê at FW HM) can be neglected when compared to the Stark broadening resulting from collisions with the charged particles that dominate for plasma densities above 10 14 cm 2 3 .…”

Section: Resultsmentioning

confidence: 99%

Effect of Ar and O₂ Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate

2002

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The in uence of gas atmospheres (at 1 torr) of different natures, both reactive (O 2 ) and inert (Ar), on the spatial evolution of the electron temperature (T e ) and electron density (N e ) of the plasma generated by laser ablation of a LiNbO 3 target is evaluated by optical emission spectroscopy techniques. It is found that the behavior of N e in the plasma produced in vacuum, argon, and oxygen atmospheres exhibit quite different trends as a function of the distance from the target to the substrate, but the behavior of T e is nearly constant. The spatial constancy of T e in all the atmospheres studied is probably related not only to the low laser irradiance used (0.06 GW cm 22 ), but also to a possible collisional decoupling of the heavy species in the central part of the expanding plasma plume where a low pressure region is formed. The fact that N e is lower in Ar than in O 2 indicates the presen ce of fewer positive ions in the plasma generated in Ar. The impact of this result on the better crystallinity observed in the LiNbO 3 lm s grown in Ar is also discussed.Index Headings: Pulsed laser ablation; Lithium niobate; Argon and oxygen atmospheres; Plasma diagnosis. INT RODUCTIO NPulsed laser deposition (PLD) has become a very promising tool for both advanced micromachining and thin lm deposition. Among the parameters involved in the PLD processes, the laser uence together with the background gas pressure (and nature) and the distance at which the substrate is located are relevant variables inuencing the lm growth process. M oreover, the ablation of solid targets produces, in most cases, a lum inous plasma form ed by neutral and ionized species whose expansion dynamics have been widely studied in order to understand the physical mechanisms controlling the thin lm deposition process and properties. 1 Nevertheless, a very limited number of works have focused on the study of the fundamental plasma parameters, such as the electron temperature and electron density, or the nature of the dominant plasma excitation and ionization processes in different spatial and temporal regions. 2-6 Although they are essential to evaluating the energy and m aterial transport in the plasma, as well as to understanding the plasm a reactivity in connection with its effectiveness in the processes of thin-lm growth and composition, such studies have only been perform ed in ablation of m etals, 2,3 graphite, 4 and YBa 2 Cu 3 O 7 . 5 Lithium niobate (LiNbO 3 ) is a well-known m aterial with excellent nonlinear properties of interest for m any applications that normally require the production of high quality thin lms.7 Although PLD has proven to be one of the m ost successful techniques in growing complex oxide materials, 8 the lms deposited by ablation of LiNbO 3 in vacuum or low pressure (,1 torr) atmospheres are often found to be Li de cient. 9,10 However, recent results indicate that when the growth is carried out at a pressure of about 1 torr, independent of the nature of the ambient atmosphere used (either inert or reactive), the LiN...

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Section: Resultsmentioning

confidence: 99%

Effect of Ar and O₂ Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate

2002

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“…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%

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

2010

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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.

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“…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

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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.

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Diagnostics of silicon plasmas produced by visible nanosecond laser ablation

Cited by 133 publications

References 40 publications

Effect of Ar and O₂ Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate

Effect of Ar and O₂ Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate

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

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Diagnostics of silicon plasmas produced by visible nanosecond laser ablation

Cited by 133 publications

References 40 publications

Effect of Ar and O2 Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate

Effect of Ar and O2 Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate

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

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Effect of Ar and O₂ Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate

Effect of Ar and O₂ Atmospheres on the Fundamental Properties of the Plasma Produced by Laser Ablation of Lithium Niobate