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Laser Induced Breakdown Spectroscopy (LIBS) has been applied to inked linen textile that belongs to a mummy's linen wrapping dated back to the Ptolemaic period (330 BC: 30 AD). The rarity of the ancient archeological piece introduced in this study has suggested the use of a model sample of currently manufactured linen for comparison purposes and optimization of the experimental conditions. The Nd:YAG laser operating at both wavelengths 532 and 1064 nm as our excitation source along with an Echelle spectrometer with an intensified charge-coupled device detector has been employed. Under the experimental conditions adopted throughout this work, the use of the visible 532 nm laser produced poorer S/B when compared to that produced by a 1064 nm laser which suggests the production of colder plasma leading to less atomization of the ablated material. Additionally, the 532 nm wavelength shows a negative behavior in ablating ink writings which was visually clear. Although, LIBS qualitative results are so comparable to that of SEM-EDX, some elements were detected only by LIBS which could be attributed to the irregularity of ink on linen. Thus, the capabilities of LIBS should be extensively exploited to the in situ measurements and analysis of archeological ink and fabrics.

An archeological Egyptian cartonnage dating back to the Greco-Roman period around the third century BC was elementally analyzed via the sample-friendly technique, Laser Induced Breakdown Spectroscopy (LIBS).

Because characterization of ink pens on documents represents an important forensic discipline, the need of legal systems for faster, in-situ and more accurate technique that identify and differentiate questioned documents involved in criminal or legal matters is of great interest. Laser-induced breakdown spectroscopy (LIBS) was experimentally proved to be a promising technique emerging in the field of forensic applications, specifically, questioned documents despite being from the same source or different source. However, the call for newly improved data analysis is unlimited and the need to know if the used ink has the same principal components or not. In the present work, the application of PCA has been demonstrated as statistics-based spectral analysis of the output resultant LIBS spectra for the forensic questioned documents analysis. The LIBS spectra were acquired from IR laser induced plasmas of black ink on regular document paper of ten brands of black gel inks commercially available in the Egyptian market. The idea behind principal component analysis is based on the loadings for the first three principal components. The obtained results have been shown to characterize ink pens used in the analysis. However, the first principal component encompasses the dominant characterization for the used pens. The results of this study indicate that Laser Induced Breakdown Spectroscopy (LIBS) of ink pens aided with PCA technique can promote the LIBS capability to faster, error-free and automatic elemental identification and differentiation for in-situ forensic purposes, specifically, questioned documents.

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