Laser-induced breakdown spectroscopy with high detection sensitivity

Abstract

Laser-induced breakdown spectroscopy (LIBS) with spatial confinement and LIBS combined with laser-induced fluorescence (LIF) have been investigated to improve the detection sensitivity and selectivity of LIBS. An obvious enhancement in the emission intensity of Al atomic lines was observed when a cylindrical wall was placed to spatially confine the plasma plumes. The maximum enhancement factor for the emission intensity of Al atomic lines was measured to be around 10. Assuming local thermodynamic equilibrium conditions, the plasma temperatures are estimated to be in the range from 4000 to 5800 K. It shows that the plasma temperature increased by around 1000 K when the cylindrical confinement was applied. Fast imaging of the laser-induced Al plasmas shows that the plasmas were compressed into a smaller volume with a pipe presented. LIBS-LIF has been investigated to overcome the matrix effects in LIBS for the detection of trace uranium in solids. A wavelength-tunable laser with an optical parametric oscillator was used to resonantly excite the uranium atoms and ions within the plasma plumes generated by a Q-switched Nd:YAG laser. Both atomic and ionic lines can be selected to detect their fluorescence lines. A uranium concentration of 462 ppm in a glass sample can be detected using this technique at an excitation wavelength of 385.96 nm for resonant excitation of U II and a fluorescence line wavelength of 409.01 nm from U II. The mechanism of spatial confinement effects and the influence of relevant operational parameters of LIBS-LIF are discussed.

Burst Mode Q:switched Laser Pulses for Plasma Excitation in LIBS Analysis

“…This is an observed dependence of the intensity of the LIBS emission response to the nature of the material analysed (Eppler et al, 1996), which manifests as variations in laser-target coupling and resultant plasma intensity variations. These two facets of the sample, which are generally lumped together as "matrix effects" (Aguilera et al, 2009;Corsi et al, 2000;Ctvrtnickova et al;Lu et al, 2010;Ma et al;Mohamed, 2008;Shen et al, 2009;Windom & Hahn, 2009), will determine LIBS signal reproducibility, namely sample composition and sample surface character.…”

Diagnostic Study of Copper Plasma in Air by Laser Induced Breakdown Spectroscopy (LIBS)

“…The plasma temperature determines the strength of the different distribution functions describing the plasma state, while the electron density overall, specifies the state of thermodynamic equilibrium of the plasma [9]. LIBS can be considered technique suitable for a wide range of different applications [10], due to its reliability [11], easy, fast, and in situ chemical analysis with a reasonable precision, detection limits, and cost, and there is no need for sample preparation [12]. Additionally, as is used to identify the the chemical elements [13][14][15], in soil studies [16], cleaning [17] , heritage and culture [18], T measurements of the plasma parameters [19,20], and Carbon Identify in low-carbon steel [15].…”

Desenvolvimento de sistema LIBS-LIF

“…Shen et al, 2009), nos quais são utilizados lasers e sistemas que permitem gerar diferentes comprimentos de onda (OPO -optical parametric oscillator) como luz de excitação, neste trabalho será construído e utilizado um sistema de laser de frequência simples. Tal escolha permite uma melhor interface do laser com o plasma e que o custo deste sistema seja consideravelmente reduzido, dado o interesse num elemento específico.…”