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Raman Spectroscopy as a New Technique for Determining the Asequence of Intersecting Lines

NCJ Number
Problems of Forensic Sciences Volume: 53 Dated: 2003 Pages: 60-73
Ewa Fabianska; Marcin Kunicki
Date Published
14 pages
This forensic research examined the usefulness of Raman spectroscopy as a nondestructive method for determining the sequence in which intersecting lines were made in creating inscriptions on a document.
The research found that Raman spectroscopy was ineffective and untrustworthy in determining the sequence in which intersecting lines were made. There was an insufficient number of positive results. There were 54.9 percent positives for heterogeneous intersections (those made with different types of instruments) and 29.1 percent positives for homogeneous intersections (those made with the same type of instrument). Also, some of the trials produced misleading results. Successive modification of parameters intended to eliminate the misleading results were unsuccessful. Intersections of homogeneous and heterogeneous lines were created with widely available writing instruments, i.e., ballpoint pens, fiber-tip pens, and roller ball pens. Also included in the examination was the intersection of a line drawn by one of the aforementioned instruments and a line created by an inkjet printer. Five inkjet printers were used. Raman spectroscopy registers two components in inelastic photons scattering on particles of the studied substance, which not only enables discriminating analysis, but in some cases identification of the substance. The spectrum obtained is characteristic for the given sample. In the current research, the Raman spectroscopy used a Foster and Freeman FORAM 685-2 spectroscope with a 685 nm wavelength laser. Measurements of spectra were conducted using a 20x objective, applying 25 percent and 100 percent of the power of the laser. Each individual investigation was begun with measurements of pure writing materials, selecting an integration time that would enable the maximum permitted intensity of peaks to be achieved. Spectra were then collected within the intersection area for the surface layer and lower layer of the intersection. Experiments were conducted no later than 1 day after the inscriptions were made. 4 tables, 6 figures, and 8 references