Chemical etching method assisted double-pulse LIBS for the analysis of silicon crystals

Abstract

Two Nd:YAG lasers working in pulsed modes are combined in the same direction (collinear arrangement) to focus on silicon (Si) crystals in reduced oxygen atmosphere (0.1 mbar) for double-pulse laser-induced breakdown spectroscopy (DP-LIBS) system. Silicon crystals of (100) and (111) orientations were investigated, and Si samples were measured either without prior treatment (''untreated'') or after fabrication of nano-pores (''treated''). Nano-pores are produced by metal coating and by chemical etching. DP-LIBS spectra were compared for different Si samples (untreated, treated, (100) and (111) orientations), for double-pulse (DP) (with 266 nm pulse followed by 1064 nm pulse) excitation and for different delay times (times between the excitation laser pulse and the detection ICCD gate); treatment by chemical etching has been studied as well. The intensity of the atomic line Si I at 288.16 nm was enhanced by a factor of about three by using the DP-LIBS signals as compared to the single-pulse (SP) signal which could increase the sensitivity of the LIBS technique. This study proved that an optimized value of the etching time of Si during etching by chemical processes and short delay times are required. Plasma parameters [the electron temperature (T e ) and the electron number density (N e )] were calculated from measured SP-and DP-LIBS spectra. The most important result of this study is the much higher DP-LIBS intensity observed on Si (100) as compared to Si (111) for measurements under the same experimental conditions. This study could provide important reference data for the design and optimization of DP-LIBS systems involved in plasma-facing components diagnostics.

Qualitative and semi-quantitative analysis of health-care pharmaceutical products using laser-induced breakdown spectroscopy

“…Usually, standard samples are required prior to qualitative analysis using LIBS to calibrate the system. However, several calibration-free LIBS techniques have been developed [13], [14], [15], [16].…”

Tungsten ion source under double-pulse laser ablation system

“…where I ik,z is the relative intensity due to electron moving from a high level i to a lower level k in an atom with ionization z, E i,z corresponds to the upper energy level, and g i,z is its statistical weight, A ik,z is the probability of transition, λ ik,z is the spectral line wavelength, U z (T ) is the atomic partition function at temperature T , L is the characteristic plasma length, N z is the emitting atoms density, T is the plasma temperature, and k B is the Boltzmann constant. [42,43] Moreover, the degree of harmonization among single examine data is enforced by using large sampling of the homogeneous object. The laser pulses are averaged to stabilize the variance of spatial overlap of laser spots on the W-target.…”

Green Synthesis of Silica- Polysaccharides Nano- composites from Sodium Silicate and Aloe Vera gel for Self-cleaning of Solar Mirrors

“…Therefore the produced compounds which have siloxane group can be used in self-cleaning process of solar mirrors to form hydrophobic surfaces using the Nano-silica composites. This will be bene t for a lot of industrial applications [53][54][55][56][57][58][59][60] .…”