Study of the relation between the plasma temperature and electron density with the spectral baseline by laser induced breakdown spectroscopy

• Grant number: 16/19065-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): December 01, 2016
• Effective date (End): February 28, 2019
• Field of knowledge: Physical Sciences and Mathematics - Physics - Atomic and Molecular Physics
• Principal Investigator: Paulino Ribeiro Villas Boas
• Grantee: Pedro Henrique Vaz Valois
• Host Institution: Embrapa Instrumentação Agropecuária. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). São Carlos , SP, Brazil
• Associated research grant: 13/07276-1 - CEPOF - Optics and Photonic Research Center, AP.CEPID

Abstract

Laser induced breakdown spectroscopy (LIBS) is a suitable atomic emission technique for rapid elemental analysis of materials in any physical state (solid, liquid or gaseous). In comparison with conventional analytical techniques, LIBS has several advantages, such as high spatial resolution, little or no sample preparation and remote detection. The spectra obtained via LIBS contain information of the plasma generated and its source matrix. However, since the plasma is formed by a combination of atoms, molecules, ions and electrons in rapid transformation, various effects arise from the combination of these particles. These are known as matrix effects and they constitute the most difficult problem to solve in LIBS. Thus, we intend to improve a calibration model for carbon by taking into account the background radiation in the plasma properties (which are related to the matrix effects). This study will be conducted by calculating the electron density and temperature (factors that can be determined spectrally by either transition lines or baseline intensity) of samples with varying carbon concentration in KBr and boric acid matrices. We will analyze the correlation between the baseline and plasma properties and the correlation between plasma properties and transition emission lines. The purpose of this analysis is to find ways to normalize carbon emission lines in function of the baseline and plasma properties. (AU)