Elemental Analysis and Plasma Diagnostics of Black Seed Using Laser-Induced Breakdown Spectroscopy

Abstract

Laser-Induced Breakdown Spectroscopy (LIBS) was employed for elemental analysis and plasma diagnostics of black seed. Plasma was generated using a Q-switched Nd: YAG laser, and emission spectra were recorded over a wide spectral range. The spectral analysis revealed the presence of major elements including C, Mg, Ca, Sr, Na, Ba, H, N, O, K, along with molecular CN bands. The influence of laser energy on plasma characteristics was systematically investigated. Emission intensity was observed to increase with laser energy due to enhanced ablation, excitation, and ionization processes, while slight saturation at higher energies was attributed to plasma shielding effects. Plasma parameters were evaluated to gain deeper insight into plasma behavior. The electron temperature, calculated using the intensity ratio method, varied from ~26,000 K to ~28,000 K with increasing laser energy. The electron number density, determined from Stark broadening of the Hα line, increased from 4.08 × 10¹⁷ cm⁻³ to 6.59 × 10¹⁷ cm⁻³. Correspondingly, the plasma frequency was found to increase from 5.75 × 10¹² Hz to 7.30 × 10¹² Hz. The results demonstrate that LIBS is a rapid, reliable, and effective technique for elemental characterization and plasma diagnostics of agricultural materials, with strong potential for applications in food quality assessment and biomedical studies.