Determination of Deposition Order of Toners, Inkjet Inks, and Blue Ballpoint Pen Combining MeV-Secondary Ion Mass Spectrometry and Particle Induced X-ray Emission

Abstract

Determination of the deposition order of different writing tools is very important for the forensic investigation of questioned documents. Here we present a novel application of two Ion Beam Analysis (IBA) techniques: Secondary Ion Mass Spectrometry using MeV ions (MeV-SIMS) and Particle Induced X-ray Emission (PIXE) to determine the deposition order of intersecting lines made of ballpoint pen ink, inkjet printer ink and laser printer toners. MeV-SIMS is an emerging mass spectrometry technique where incident heavy MeV ions are used to desorb secondary molecular ions from the uppermost layers of an organic sample. In contrast, PIXE provides information about sample elemental composition through characteristic X-ray spectra coming from greater depth. In the case of PIXE, the information depth depends on incident ion energy, sample matrix and self-absorption of X-rays on the way out from the sample to the X-ray detector. The measurements were carried out using heavy ion microprobe at the Ruđer Bošković Institute. Principal Component Analysis (PCA) was employed for image processing of the data. We will demonstrate that MeV-SIMS alone was successful to determine the deposition order of all intersections not involving inkjet printer ink. The fact that PIXE yields information from deeper layers was crucial to resolve cases where inkjet printer ink was included due to its adherence and penetration properties. This is the first time the different information depths of PIXE and MeV-SIMS have been exploited for a practical application. The use of both techniques, MeV-SIMS and PIXE allowed the correct determination of deposition order for four out of six pairs of samples.

Depth profiling of Cr-ITO dual-layer sample with secondary ion mass spectrometry using MeV ions in the low energy region

“…Secondary Ion Mass Spectrometry using MeV ions (MeV SIMS) 1 is a fairly new Ion Beam Analysis (IBA) technique that is being increasingly used for the analysis and imaging of organic materials in various fields, such as forensics (fingerprints 2 and inks 3 – 5 ), cultural heritage (paints 6 ), biology (plants 7 and tissues 8 ), etc. Conventional keV SIMS, on the other hand, is a well-established technique used mainly in the analysis and depth profiling of inorganic materials, with the most popular application in the semiconductor industry, i.e.…”

Determining the chronological sequence of inks deposited with different writing and printing tools using ion beam analysis

“…Recently, ion beam analytical techniques, in particular MeV secondary ion mass spectrometry (MeV-SIMS) and particle-induced X-ray emission (PIXE), have been used for forensic analysis of inks/ laser toners deposited on the documents. The order of ink deposition was identified by the presence of a gap at the ink distribution map, for example, the ink deposited first showed a gap or discontinuity at the crossing and the ink deposited on top showing continuity [13][14][15][16].…”

Simple and Cost-Efficient Classification of Ballpoint Pen Inks Using Digital Color Analysis

“…Mass spectrometry provides accurate determination of a wide variety of components in writing materials with the help of mass spectra databases. , In addition, mass spectrometry solely or in tandem with X-ray methods (particle induced X-ray emission) can determine the deposition order of the inks from different writing tools. Relatively simple sample preparation and a small amount of material required for analysis are the indisputable advantages of this method.…”