Silica Nanoparticle and Microwave Plasma Torch Effects on Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a commonly used elemental analysis technique, often combined with other methods to achieve effective detection of element concentrations in samples. In this work, we investigated the effects of silica nanoparticles and a microwave plasma torch (MPT) on the emission spectral signals of titanium (Ti) in LIBS. The laser energy was optimized, and the emission intensities at different silica nanoparticle concentrations were compared. Furthermore, the finite-difference time-domain (FDTD) method was employed to simulate variations in electric field intensity in order to verify the optimal nanoparticle concentration, and time-resolved experiments were conducted to explore the evolution of the emission spectra. The results silica nanoparticles significantly increase plasma electron density, which in turn enhances both emission intensity and signal-to-noise ratio (SNR). In addition, it demonstrates that the MPT extends the plasma lifetime, thereby enhancing the accumulated emission signal. When silica nanoparticles were combined with MPT using nanoparticle-enhanced laser-induced breakdown spectroscopy (MPT-NELIBS), it achieved substantial improvements in spectral intensity and SNR and reduce the dependence of NELIBS on nanoparticles. Ultimately, this method exhibited excellent performance in the quantitative detection of Ti, with the determination coefficient (R²) of the calibration curve increasing to 0.999 and the limit of detection (LOD) decreasing to 0.14 parts-per-million (ppm), highlighting its great potential for highly sensitive trace element analysis.