الفهرس 
الغلاف العربىOnly 14 pages are availabe for public view
 |  | from | 173 |  |  |
| | | from | 173 | | |
Abstract
Forensic examination of questioned documents involves numerous types of analysis, for example, handwriting, ink, and paper analysis. Historically, the comparison of paper was based on physical properties such as dimensions, colour, and weight. More recently, it has focused on the elements present as a result of the manufacturing and handling processes, as well as impurities in the starting materials.
IOn (Cs +) was added intentionally during paper -ufacture for protecting the papers against forgery and counterfeiting by
sorbing cesium ions (es+) on kaolin, used as special filler in papemaking. Selection of Cs + as taggant primarily depends on the absence of natural kaolin from cesium and it has the feature to help document examiners to identifY fraud in sensitive documents.
The sorption of Cs + from their aqueous solutions by kaolin was studied as a function of pH, shaking time, cesium initial concentration, and mass of kaolin using batch technique. The results showed that solution Coutaining 10 mg/L Cs + and 250 mg of Kaolin at pH 6 can be used to modifY the kaolin.
Paper hand sheets were prepared containing vanous percentages of the modified kaolin. The mechanical and optical properties of paper handsheets were studied. The prepared paper handsheets were irradiated by gamma irradiation using five doses (3, 6, 9, 12 and 15 kGy) at dose rate 0.817 Gy/s. Fourier transform infra-red (FTIR) spectroscopy was used to study the effect of kaolin modification by Cs + and gamma irradiation on paper handsheets properties. The results indicated that modified kaolin enhanced the mechanical and optical properties of paper handsheets. The maximum y-irradiation dose used in these series of experiments (15 kGy) did not have any negative effect on paper handsheets properties. Electron spin resonance (ESR) spectroscopy and laser induced breakdown spectroscopy (UBS) were also used. They provided rapid, sensitive and nondestructive techniques in differentiating between the paper handsheets containing native kaolin and that having modified kaolin with Cs +. This study presents a new concept in manufacturing security papers and anti-counterfeiting applications.
Keywords
Forensic document examination, Ion exchange, Cesium (Cs +), Kaolin, Security paper, Anti-counterfeiting, FTIR spectroscopy, ESR Spectroscopy, and UBS.