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Microspectrophotometers are used for spectral analysis of inks and papers by UV-visible-NIR and fluorescence spectroscopy and imaging.
UV-visible-NIR spectra of two black inks
Microspectrophotometers are used to analyze pigments, dyes and additives of inks and papers.
Questioned documents are any type of document that needs to be analyzed. They may range from currency, passports, forgeries to historical documents. Most documents consist of the substrate, most commonly paper, and the ink.
Ink and other types of coating materials are used to impart information on the document. They consist of three main components plus any special additives required for create or maintain certain properties. The first component is the colorant which may either be a pigment or dye. The second is the Vehicle which acts as a binder to hold the ink together and to the surface upon application of the ink. Solvents are used to modify the viscosity and drying properties of inks whereas Additives can be anything from ultraviolet absorbers (UVA), designed to protect the paint from solar damage, to biocides to inhibit bacterial growth.
Paper is one of the most common substrates for printing. Spectroscopic analysis of the paper can yield everything from the identity of the wood pulp to various security features embedded within the sheet. The analysis of paper can be quite challenging due to its variability on the microscopic scale. However, properly designed instruments and experiments can eliminate this variable.
UV-visible-NIR microspectrophotometers, such as the 20/20 PV™, are used to analyze the dyes and pigments as well as the paper and many of the security features contained within such documents. The advantage of using microspectrophotometers is that they can be used to analyze even the smallest micro-printing and security features. This makes these instruments very useful for everything from forensic analysis to developing new ink and paper formulations.
UV-visible-NIR microscopes, such as the UVM-1™, are used to analyze documents and their security features. WIth true deep UV imaging, coupled with multiple light sources and NIR imaging out to 1700 nm, this system has far more discrimination than simple video systems. The 20/20 PV™ can also be equipped with this type of imaging to give you even more levels of discrimination.
Raman microspectrometers, such as the CRAIC Apollo™, are also used to analyze the dyes and pigments of the inks. Many of these can be analyzed in great detail with Raman spectroscopy.
To learn more about microspectroscopy and applications such as document examination, select one of the following links: