Influence of Planar Mirror Confinement and Temperature Control upon the Elemental Analysis of Soil by Laser-Induced Breakdown Spectroscopy

To improve the signal-to-noise ratio of laser-induced breakdown spectroscopy, an enhancement combining planar mirror constraint and temperature control is reported. Theoretical analysis of planar mirror constraint and temperature control reveals that the interaction of the two mechanisms further enhances the spectral response. The spectral intensities and signal-to-noise ratios of samples with and without the enhancements were compared. The results showed that the enhancement factors for Cd, Fe, Al, and Pb were 2.50, 2.78, 2.66, and 2.47, respectively. The corresponding signal-to-noise ratio enhancement factors were 1.83, 2.11, 1.98, and 1.91. The coefficients of determination R-2 for Cd and Pb were 0.912 and 0.962 without enhancement but were 0.969 and 0.990 with the dual mechanism. The limits of detection for Cd and Pb were 74.6 mg/kg and 62.3 mg/kg without enhancement but were 58.4 mg/kg and 46.7 mg/kg with the dual mechanism. This study shows that the enhancement with planar mirror constraint and temperature control improved the signal-to-noise ratio and accuracy.