Fig. 1. Schematic diagram of LIBS experimental scheme

Fig. 2. The spectra of air when charcoal is burning

Fig. 3. The spectra of smoke aerosol

Fig. 4. The spectra of fruit charcoal

Fig. 5. The spectra of ash

Fig. 6. Comparison of characteristic spectral lines of (a) C and (b) H in the fruit charcoal and ash

Fig. 7. PCA results of air with and without combustion. (a) Principal component contribution rate and cumulative contribution rate; (b) Result of differentiation

Fig. 8. PCA results of fruit charcoal and ash. (a) Principal component contribution rate and cumulative contribution rate; (b) Result of differentiation