Analytical methods for document dating

Posted by / 23-Aug-2018 05:13

Analytical methods for document dating

These spectra are useful for characterizing and identifying (e.g. X-ray fluorescence is commonly used for solids in which secondary X-ray emission is generated by excitation of a sample with X-rays.The technique has found extensive applications in determining the elemental profile of the ink and paper of suspect currency.The morphology of ink lines on paper is examined with the help of optical microscopy that uses visible light for illumination, and glass lenses for magnifying and focusing.This may allow classification of inks being examined, discrimination between inks being compared, or may, in rare occasions, individualize the writing instrument through its performance characteristics.It should be stressed, however, that, if the components of interest are analyzed without isolating from the matrices, their chemical identification is practically impossible; as a rule, only characterization of the major functional groups of the compound can be accomplished.

Energy dispersive X-ray microanalysis combined with scanning electron microscopy (SEM-EDX) is an important analytical method due to its ability to examine surface morphology with high resolution and depth of field, and to produce qualitative and quantitative elemental analyses of selected microareas by detection of characteristic X-rays.The method allows discrimination between similarly colored inks at a considerably higher degree of certainty than it could be done using optical microscopy or evaluation by the unaided eye.Microspectrofluorimetry has been used for measuring the emission spectra of ink on paper and of some additives to paper (fluorescent fibers, optical brighteners).Many writing and printing inks contain detectable elements that can be used for characterization and comparison by SEM-EDX.In addition some writing inks have detectable trace rare organometallic compounds added which indicate the year of its production.

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