Comparative Study of Nd:YAG Laser-Induced Breakdown Spectroscopy And Transversely Excited Atmospheric CO2 Laser-Induced Gas Plasma Spectroscopy on Chromated Copper Arsenate Preservative-Treated Wood

摘要

Taking advantage of the specific characteristics of a transversely excited atmospheric (TEA) CO2 laser, asophisticated technique for the analysis of chromated copper arsenate (CCA) in wood samples has beendeveloped. In this study, a CCA-treated wood sample with a dimension of 20 mm× 20 mm and a thicknessof 2 mm was attached in contact to a nickel plate (20 mm× 20 mm× 0.15 mm), which functions as asubtarget. When the TEA CO2 laser was successively irradiated onto the wood surface, a hole with adiameter of approximately 2.5 mm was produced inside the sample and the laser beam was directly impingedonto the metal subtarget. Strong and stable gas plasma with a very large diameter of approximately10mm was induced once the laser beam had directly struck the metal subtarget. This gas plasmathen interacted with the fine particles of the sample inside the hole and finally the particles were effectivelydissociated and excited in the gas plasma region. By using this technique, high precision and sensitiveanalysis of CCA-treated wood sample was realized. A linear calibration curve of Cr was successfullymade using the CCA-treated wood sample. The detection limits of Cr, Cu, and As were estimated to beapproximately 1, 2, and 15 mg∕kg, respectively. In the case of standard LIBS using the Nd:YAG laser, theanalytical intensities fluctuate and the detection limit was much lower at approximately one-tenth thatof TEA CO2 laser.