The study of modern writing means on documents with spectroscopic methods

Abstract

Material analysis of writing means is very important part of forensic examination of the questioned documents. Mostly is it used to confirm/refute the authenticity of the document or dating the time of document formation. Nowadays, commonly used writing means can be divided to ballpoint, ink and gel pens, according to the nature of their writing fluid cartridge. The various group of writing means differ in ink composition and principle of supplying writing materials on a substrate. During examination of the document usually routine analysis such as optical microscopic methods are applied first. Their preliminary results can facilitate the choice of other methods which are needed to submit a sample. Widely used are spectroscopic (mostly non-destructive) and chromatographic (destructive) methods. The aim of our study was to utilize a combination of suitable spectroscopic methods in IR region and XRF spectroscopy in order to develop the most appropriate methods of measurement and subsequent data processing in identification of the writing resource. The database of 19 model samples of different kinds of blue pens applied on paper substrate was created. More attention was fixed on micro-FTIR and FTIR analysis. We focused on searching for the optimum technique enabling the analysis of thin lines on a paper substrate and subsequent separation of the spectrum of writing means. It was established what is the minimum required number of measurements from a single sample. In the spectra, the correlation/difference between groups of writing means (ball, gel and roller ball pens) and between individual means within a particular group were studied. The results were supplemented by elemental analysis and by XRF method.