title: Feasibility for non-destructive discrimination of natural and beryllium-diffused sapphires using Raman spectroscopy.
abstract: Raman spectroscopy based non-destructive discrimination between natural and beryllium-diffused (Be-diffused) sapphires has been attempted. The initial examination of Raman image acquired on a sapphire revealed that microscopic structural and compositional heterogeneity was apparent in the sample, so acquisition of spectra able to represent a whole body of sapphire rather than a localized area was necessary for a reliable discrimination. For this purpose, a wide area illumination (WAI) scheme (illumination area: 28.3mm(2)) providing a large sampling volume was employed to collect representative Raman spectra of sapphires. Upon the diffusion of Be into a sapphire, the band shift originated from varied lattice structure by substitution of Be at cation sites was observed and utilized as a valuable spectral signature for the discrimination. In the domain of principal component (PC) scores, the groups of natural and Be-diffused sapphires were identifiable with minor overlapping and the cross-validated discrimination error was 7.3% when k-Nearest Neighbor (k-NN) was used as a classifier.
authors.affiliation: Analytical Spectroscopy Lab, Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 133-791, Korea.
authors.forename: Kyeol
authors.initials: K
authors.lastname: Chang
authors.affiliation: Analytical Spectroscopy Lab, Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 133-791, Korea.
authors.forename: Sanguk
authors.initials: S
authors.lastname: Lee
authors.affiliation: Analytical Spectroscopy Lab, Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 133-791, Korea.
authors.forename: Jimin
authors.initials: J
authors.lastname: Park
authors.affiliation: Analytical Spectroscopy Lab, Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 133-791, Korea. Electronic address: hoeil@hanyang.ac.kr.
authors.forename: Hoeil
authors.initials: H
authors.lastname: Chung
keywords: Be-diffused sapphire; Multivariate discrimination; Natural sapphire; Representative Raman sampling