Laser-Induced Breakdown Spectrosocopy with Supercontinuum Enhancement

Abstract

Agriculture has been one of the most critical industries since ancient times. However, severe food shortages are predicted in the near future due to a rapid increase in population and climate change. One strategy to address this challenge is the implementation of smart agricultural practices, which involves integrating modern technology into farming to improve crop yields and efficiency. A key component of this approach is soil analysis, which involves studying the elemental composition of field soil to evaluate nutrient availability or detect potential contamination. A technique gaining attention is laser-induced breakdown spectroscopy (LIBS), which generates a plasma on the sample surface and analyzes the emitted photons to determine the elemental composition. LIBS is rapid and reliable, yet it still faces challenges in detecting certain elements with sufficient sensitivity. To address this limitation, the present work proposes the combination of LIBS with a supercontinuum light source to illuminate the plasma and thereby enhance detection rates.

Atomic emission and absorption spectroscopy were performed using two supercontinuum lasers: a self-built nanosecond supercontinuum laser and a commercial picosecond supercontinuum laser. Sodium and potassium samples on graphite substrates were analyzed through signal-to-noise ratio (SNR) and standard deviation evaluations.

Picosecond supercontinuum illumination enhanced emission spectra by up to 18 % provided higher SNR, stability, and reproducibility than the nanosecond source. Potassium showed greater enhancement, yet standard deviation analysis revealed that averaging hundreds of measurements was necessary due to plasma fluctuations. Absorption measurements revealed only broadband continuum absorption, likely caused by high plasma density masking element-specific transitions.