Determination of the sequence of intersecting lines using Focused Ion Beam/Scanning Electron Microscope

Area of Science:

• Forensic Science
• Materials Science
• Analytical Chemistry

Background:

• Document examination traditionally relies on microscopy and chemical tests.
• Determining the sequence of ink or material application in document forgery is crucial.
• Advanced analytical techniques can offer higher precision and certainty.

Purpose of the Study:

• To validate the combined use of Focused Ion Beam (FIB) and Scanning Electron Microscopy/Energy-Dispersive X-ray (SEM/EDX) for analyzing document line crossings.
• To assess the accuracy and effectiveness of FIB/SEM/EDX in determining the order of heterogeneous line intersections.

Main Methods:

• Samples with intersecting lines (gel pen and red sealing ink) were prepared.
• Focused Ion Beam (FIB) milling was performed for cross-sectioning.
• Scanning Electron Microscopy (SEM) was used for high-resolution imaging.
• Energy-Dispersive X-ray (EDX) spectroscopy analyzed elemental composition and distribution at intersections.

Main Results:

• The FIB/SEM/EDX technique accurately determined the sequence of line crossings.
• 100% correctness was achieved when analyzing intersections of gel pen and red sealing ink.
• Elemental distribution analysis via EDX provided chemical evidence for the layering of materials.

Conclusions:

• The combination of FIB/SEM/EDX is a highly effective method for forensic document examination.
• This technique provides definitive evidence regarding the sequence of markings on documents.
• FIB/SEM/EDX offers a powerful tool for the overall examination and authentication of documents.