Determination of the sequence of intersecting lines from laser toner and seal ink by Fourier transform infrared microspectroscopy and scanning electron microscope / energy dispersive X-ray mapping

The aim of this study was to verify that the combination of Fourier transform infrared microspectroscopy and scanning electron microscope / energy dispersive X-ray mapping could be applied to line intersection problems. The spectral data of red seal ink, laser toner and their intersections, such as peak location and peak intensity, were described. Relative peak height ratios of different chemical components in intersecting lines were used to distinguish the sequences. Energy dispersive X-ray mapping characteristics of intersecting areas were also detailed. The results show that both the laser toner and the seal ink appear on the surface of intersections, regardless of the sequence. The distribution of the two inks on the surface is influenced not only by the sequence of heterogeneous lines but also by diffusion. Fourier transform infrared microspectroscopy and scanning electron microscope/energy dispersive X-ray mapping are able to explore the chemical components and the corresponding elemental distribution in the intersections. The combination of these two techniques has provided a reliable method for sequencing intersecting lines of red seal ink and laser toner, and more importantly, this method may be a basis for sequencing superimposed lines from other writing instruments.