Area: LOD

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4 articles found

Effect of experimental parameters and resulting analytical signal statistics in laser-induced breakdown spectroscopy

Author: Klus, J. ; et. al.

Journal: Spectrochimica Acta Part B: Atomic Spectroscopy (2016)

Fundamentals

DOI: 10.1016/j.sab.2016.10.002

Authors
Kaiser, J. ; Novotný, J. ; Novotný, K. ; Pořízka, P. ; Prochazka, D.

Keywords

Laser-induced breakdown spectroscopy; Generalized extreme value distribution; shot-to-shot statistics ;

Abstract

The purpose of this work is to provide detailed study of statistical behavior of different types of analytical signals in typical of Laser-Induced Breakdown Spectroscopy (LIBS) measurements. The main goal of this work is to justify usage of arithmetic mean and standard deviation as statistical estimates of expected value of selected analytical signal. In contrary to the general assumption that LIBS data show Gaussian distribution, this paper deals with the hypothesis that the data rather demonstrate Generalized Extreme Value Distribution. The study is realized on 10 selected lines measured on NIST glass standard. In order to cover wide range of possible applications three different spectra internal standardization techniques and their influence on distribution were studied. Finally, assuming that the data comes from a single distribution and the central limit theorem is valid, the influence of accumulations on the line distribution is examined and discussed. Statistical tools used and described in this paper can be utilized by other researchers to confirm their hypotheses and verify utilization of Gaussian distribution or even novel data processing methods.

Area:

LOD

Material:

Soft borosilicate glass

Elements:

Lines [nm]:

Mg II 279.55 nm Mg II 280.27 nm

Lines [nm]:

Ca II 393.37 nm Ca II 396.85 nm

Lines [nm]:

Na I 589.00 nm

Lines [nm]:

Al I 309.27 nm

Lines [nm]:

Si I 288.16 nm

...

Emmision lines:
Mg II 279.55 nm
Mg II 280.27 nm
Si I 288.16 nm
Al I 309.27 nm
Ca II 393.37 nm
Ca II 396.85 nm
Sr II 421.55 nm
Ba II 493.41 nm
Na I 589.00 nm
K I 766.49 nm

Detection of visually unrecognizable braking tracks using Laser-Induced Breakdown Spectroscopy, a feasibility study

Author: Prochazka, D. ; et. al.

Journal: Spectrochimica Acta Part B: Atomic Spectroscopy (2016)

Applications

DOI: 10.1016/j.sab.2016.02.013

Authors
Bilík, M. ; Brada, M. ; Bradáč, A. ; Kaiser, J. ; Klus, J. ; Novotný, J. ; Novotný, K. ; Pořízka, P. ; Prochazková, P. ; Semela, M. ; Ticová, B.

Keywords

Braking tracks; Forensic; LIBS; Tire treads; Laser-Induced Breakdown Spectroscopy;

Abstract

Identification of the position, length and mainly beginning of a braking track has proven to be essential for determination of causes of a road traffic accident. With the introduction of modern safety braking systems and assistance systems such as the Anti-lock Braking System (ABS) or Electronic Stability Control (ESC), the visual identification of braking tracks that has been used up until the present is proving to be rather complicated or even impossible. This paper focuses on identification of braking tracks using a spectrochemical analysis of the road surface. Laser-Induced Breakdown Spectroscopy (LIBS) was selected as a method suitable for fast in-situ element detection. In the course of detailed observations of braking tracks it was determined that they consist of small particles of tire treads that are caught in intrusions in the road surface. As regards detection of the “dust” resulting from wear and tear of tire treads in the environment, organic zinc was selected as the identification element in the past. The content of zinc in tire treads has been seen to differ with regard to various sources and tire types; however, the arithmetic mean and modus of these values are approximately 1% by weight. For in-situ measurements of actual braking tracks a mobile LIBS device equipped with a special module was used. Several measurements were performed for 3 different cars and tire types respectively which slowed down with full braking power. Moreover, the influence of different initial speed, vehicle mass and braking track length on detected signal is discussed here.

Area:

Industry ; LOD ; Traffic

Material:

Braking track

Elements:

Lines [nm]:

Zn I 328.23 nm Zn I 330.26 nm

Emmision lines:
Zn I 328.23 nm
Zn I 330.26 nm

Estimating the grade of Mg corrosion using laser-induced breakdown spectroscopy

Author: Pořízka, P. ; et. al.

Journal: Journal of Analytical Atomic Spectrometry (2015)

Applications

DOI: 10.1039/C5JA00257E

Authors
Čelko, L. ; Kaiser, J. ; Klus, J. ; Novotný, K. ; Prochazka, D. ; Ročňáková, I. ; Sládková, L. ; Spotz, Z. ; Šperka, P.

Keywords

Abstract

We present a report on the potential use of the Laser-Induced Breakdown Spectroscopy (LIBS) technique for direct investigation of Mg corrosion and related optimization of the table-top LIBS system. Moreover, the preliminary study to prove the capability of this LIBS technique for the estimation of corrosion grade is given. In order to simulate the real corrosive environment, Mg samples were prepared in a constant climate chamber. We show that the corrosive layer on the sample surface significantly affects the properties of laser–matter interactions, i.e. among other parameters causing the matrix effect. Consequently, the properties and persistence of laser-induced plasmas (LIPs) and their composition, generated on such degraded surfaces, essentially differ. Collected radiation of LIP is then analysed and ratios of ionic to atomic Mg spectral lines are correlated with the grade of magnesium corrosion, i.e. content of Mg(OH)2 on the sample surface. The content of Mg(OH)2 is also correlated with plasma temperature as well as with the electron number density of LIP. Additionally, X-ray diffraction (XRD) analysis and optical profilometry were utilized to obtain more comprehensive information about the degradation grade of high purity Mg samples.

Area:

Industry ; LOD

Material:

High purity magnesium

Elements:

Lines [nm]:

Mg I 309.30 nm Mg I 309.69 nm Mg I 382.94 nm Mg I 383.23 nm Mg I 516.73 nm Mg I 517.27 nm Mg I 518.36 nm Mg I 571.11 nm Mg I 293.67 nm Mg II 293.65 nm Mg II 448.13 nm

Emmision lines:
Mg II 293.65 nm
Mg I 293.67 nm
Mg I 309.30 nm
Mg I 309.69 nm
Mg I 382.94 nm
Mg I 383.23 nm
Mg II 448.13 nm
Mg I 516.73 nm
Mg I 517.27 nm
Mg I 518.36 nm
Mg I 571.11 nm

Detection of tire tread particles using laser-induced breakdown spectroscopy

Author: Prochazka, D. ; et. al.

Journal: Spectrochimica Acta Part B: Atomic Spectroscopy (2015)

Applications

DOI: 10.1016/j.sab.2015.03.011

Authors
Bilík, M. ; Bradáč, A. ; Kaiser, J. ; Klus, J. ; Novotný, J. ; Novotný, K. ; Pořízka, P. ; Prochazková, P. ; Semela, M. ; Ticová, B.

Keywords

LIBS; Laser-induced breakdown spectroscopy; Tire tread; Optimization ;

Abstract

The objective of this paper is a study of the potential of laser induced breakdown spectroscopy (LIBS) for detection of tire tread particles. Tire tread particles may represent pollutants; simultaneously, it is potentially possible to exploit detection of tire tread particles for identification of optically imperceptible braking tracks at locations of road accidents. The paper describes the general composition of tire treads and selection of an element suitable for detection using the LIBS method. Subsequently, the applicable spectral line is selected considering interferences with lines of elements that might be present together with the detected particles, and optimization of measurement parameters such as incident laser energy, gate delay and gate width is performed. In order to eliminate the matrix effect, measurements were performed using 4 types of tires manufactured by 3 different producers. An adhesive tape was used as a sample carrier. The most suitable adhesive tape was selected from 5 commonly available tapes, on the basis of their respective LIBS spectra. Calibration standards, i.e. an adhesive tape with different area content of tire tread particles, were prepared for the selected tire. A calibration line was created on the basis of the aforementioned calibration standards. The linear section of this line was used for determination of the detection limit value applicable to the selected tire. Considering the insignificant influence of matrix of various types of tires, it is possible to make a simple recalculation of the detection limit value on the basis of zinc content in a specific tire.

Area:

Industry ; LOD ; Traffic

Material:

Braking track ; Tire

Elements:

Lines [nm]:

Zn I 328.23 nm Zn I 330.26 nm Zn I 334.50 nm

Emmision lines:
Zn I 328.23 nm
Zn I 330.26 nm
Zn I 334.50 nm

Area: LOD

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