Date of Graduation
Eberly College of Arts and Sciences
Forensic and Investigative Science
Keith B. Morris
The inelastic scattering effects seen in Normal Raman (NR) spectroscopy were first observed in 1928 by Raman and Smekal. One problem encountered with Raman spectroscopy was the Raman scattering being masked by the intense fluorescence produced when the sample was exposed to the laser. One discovery in 1974 by Fleischmann et al. helped to maximize the Raman signal and came to be known as surface-enhanced Raman spectroscopy (SERS). In this research, spectral libraries of dyes used in pens and Raman spectra produced from the analysis of inks were evaluated in order to determine the extent to which inks can be discriminated using Raman spectra. The acid dyes were analyzed at 532 nm using NR and SERS and at 785 nm using NR. The results of the acid dye analyses indicated that there was not a single method that could generate usable spectra for all the dyes. NR at 532 nm produced the most usable spectra. The inks were analyzed both in situ and by extraction with methanol. They were analyzed at 532 nm using NR and SERS. The in situ analyses only produced usable results for 7 of the inks analyzed. The results of the ink analyses showed the potential for SERS to produce enhanced spectra over NR. Extraction SERS yielded usable spectra for 28 of the 31 inks analyzed, compared to 7 inks and 2 inks for in situ NR and extraction NR, respectively. The extent of the SERS enhancement varied between samples, and some of the spectra generated could not be differentiated.
Elswick, Patricia T., "Evaluation of the Use of Raman Spectroscopic Techniques in Ink Analyses" (2012). Graduate Theses, Dissertations, and Problem Reports. 555.