Non-destructive method for species identification of historical wooden statues using NIR spectroscopy：Analysis using wood samples of the internationally authorized collection

Abstract

To identify wood species of historically valuable wooden artifacts in a non-invasive manner, the applicability of near infrared（NIR）spectroscopy was examined using reference wood samples（ sample number：TWTw） from the wood library of the Forestry and Forest Products Research Institute. Diffuse-reflectance NIR spectra were obtained from five standard wood samples of the 10 tree species：five softwood species of Chamaecyparis obtusa, Cryptomeria japonica, Sciadopitys verticillata, Thujopsis dolabrata, and Torreya nucifera, and five hardwood species of Aesculus turbinata, Cercidiphyllum japonicum, Cinnamomum camphora, Prunus jamasakura, and Zelkova serrata . A principal component analysis（PCA）model was developed from the second derivative spectra of two different regions of wavelength 830－1150 nm and 1300－2500 nm. By PCA using the wavelength region 830－1150 nm, the score plot of the first two components clearly showed separation of the data of Torreya nucifera from the data of other samples. By PCA using the wavelength region 1300－2500 nm of wavelength, the score plot of the first two components clearly showed separation of the wood sample data into softwood and hardwood clusters. These results imply that NIR spectroscopy combined with PCA is a possible technique for the identification of historically valuable wooden artifacts.