To overcome the shortcomings
of low detection sensitivity and high
spectral line background noise of traditional laser-induced breakdown
spectroscopy (LIBS), a method of combining flat mirrors with gold
nanoparticles (Au-NPs) was proposed. First, independent plane mirror
and Au-NPs experiments were performed by using aluminum alloy samples.
After that, the samples were placed under four conditions (None-LIBS;
Three mirrors-LIBS; 20 nm Au-NPs-LIBS; 20 nm Au-NPs and Three mirrors-LIBS),
and the differences between various spectral parameters were analyzed.
The experimental results show that the optimal number of plane mirrors
is 3, and the optimal size of gold nanoparticles is 20 nm. When 20
nm Au-NPs and Three mirrors are used in combination, the plasmonic
spectral intensity can be effectively enhanced. The enhancement factor
is up to 2.98 (Fe II 240.45 nm), and the signal-to-noise ratio (SNR)
is significantly improved up to 10.03. The variation of the plasma
temperature between 1 and 5 μs was also investigated, and the
experimental results showed that the plasma temperature could be increased
by the flat mirror, while the electron temperature was almost unchanged
under the action of Au-NPs. It is shown that the combination of the
two enhancement methods can effectively increase the spectral intensity
and improve the signal-to-noise ratio, which will help to improve
the detection performance of the LIBS system.