Nanoparticle Enhanced Laser Induced Breakdown Spectroscopy for Improving the Detection of Molecular Bands

Abstract

Enhancement of molecular band emission in laser-induced plasmas is important for improving sensitivity and limits of detection in molecular sensing and molecular isotope analysis. In this work we introduce the use of Nanoparticle Enhanced Laser Induced Breakdown (NELIBS) for the enhancement of molecular band emission in laser-induced plasmas, and study the underlying mechanisms responsible for the observed enhancement. The use of Ag nanoparticles leads to an order of magnitude enhancement for AlO (B2Σ+ → Χ+ Σ+) system emission from an Al-based alloy. We demonstrate that the mechanism responsible for the enhancement of molecular bands differs from that of atomic emission, and can be traced down to the increased number of atomic species in NELIBS which lead to AlO molecular formation. These findings showcase the potential of NELIBS as a simple and viable technology for enhancing molecular band emission in laser-induced plasmas

Perspective on the use of nanoparticles to improve LIBS analytical performance: nanoparticle enhanced laser induced breakdown spectroscopy (NELIBS)

“…The higher number density of the NELIBS plasma can cause a faster decrease of the excitation temperature. As a consequence, at the beginning of plasma expansion, the excitation temperature in NELIBS is higher than in LIBS and within some hundreds of nanoseconds the situation inverts [22], as reported in Tab1. During the plasma evolution, the enhancement ratio of different transitions is different [7].…”

“…During the plasma evolution, the enhancement ratio of different transitions is different [7]. For this reason, in order to estimate the actual enhancement, we determined the total number density of emitters in NELIBS and LIBS by assuming a Boltzmann distribution for their population at the experimental temperature [7,22]. Table 2 shows the dependence of the intensity enhancement on laser wavelength.…”

Improving the Detection Sensitivity for Laser-Induced Breakdown Spectroscopy: A Review

“…In addition, Wu et al [75] achieved a LOD of 13 ppb for K by combining amphiphiles with nanoparticles for adsorption and enrichment of K in KCl solution. The application of nanoparticles for molecular bands detection was studied by Koral et al [76] An order of magnitude enhancement of AlO signal was achieved by 20 nm Ag nanoparticles when detecting aluminum alloy. Metal nanoparticles are simple to use and can greatly improve the detection sensitivity; however, metal nanoparticles will contaminate samples.…”

Nanoparticle enhanced laser induced breakdown spectroscopy of liquid samples by using modified surface-enhanced Raman scattering substrates

“…In later years, the NELIBS approach has been studied in detail by the inventors and other researchers (e.g. [3][4][5][6][7][8][9][10][11]). It was shown, that the metal the NPs are made of, the surface concentration, as well as the laser wavelength and irradiance all have a great impact on the signal enhancement achievable [3].…”

“…This led to the realization that in mainstream LIBS instruments working with significantly longer gate widths (e.g. ms), only smaller signal enhancement factors can be attained [3,5] and that the enhancement also depends on the excitation potential of the electronic transition of the element studied [2][3][4]. It was also demonstrated that the NELIBS analysis of liquid samples is also possible, if they are dried onto substrates formerly prepared by NP deposition [4,6,7] or by NP embedding [11].…”