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Development of Advanced Raman Spectroscopy Methods and Databases for the Evaluation of Trace Evidence and the Examination of Questioned Documents-Phase II

NCJ Number
Date Published
May 2013
119 pages
A multidisciplinary collaboration furthered the application of Raman spectroscopy and non-destructive, surface-enhanced Raman scattering (SERS) analysis techniques as applied to the evaluation of trace evidence and the examination of questioned documents.
Through the sharing of instrumentation, reference materials, and their respective research expertise, the team assembled a reference database of spectra for forensic applications and optimized new techniques for non-destructive SERS analysis. This was Phase II of a project that in Phase I demonstrated that SERS can be applied to the identification of organic colorants present in inks, paints, and textile fibers. The techniques developed in Phase I are especially suited for handling microscopic samples; textile dyes were identified from samples as small as a 1-millimeter section of a single silk fibril of 50-micrometer diameter and even from textiles severely degraded by burial. Analytical procedures for SERS of a number of representative dyes were developed, and the core of a high-quality spectral database was assembled as a proof of concept experiment, and innovative non-destructive approaches were investigated. Phase II, which is covered in the current report, further explored the application of Raman spectroscopy to the evaluation of trace evidence and the examination of questioned documents. The objective was to solve the problems that have so far limited the applicability of this technique to the identification of organic colorants and other materials in trace amounts. Phase II optimized a highly reproducible method of producing silver nanoparticles based on a microwave-assisted reduction of silver sulfate with glucose in the presence of sodium citrate as a capping agent. The development of the SERS database continued by adding spectra of several more natural and synthetic dyes as well as controlled substances. A non-destructive sampling approach was refined, and validation studies were conducted on the methods developed. 60 figures, 3 tables, 32 references, and a listing of dissemination presentations and publications

Date Published: May 1, 2013