Abstract
Raman spectroscopy has been shown to be a viable method for explosives detection. Currently most forensic Raman systems are either large, powerful instruments for laboratory experiments or handheld instruments for in situ point detection. We have chosen to examine the performance of certain benchtop Raman probe systems with the goal of developing an inexpensive, portable system that could be used to operate in a field forensics laboratory to examine explosives-related residues or samples. To this end, a rugged, low distortion line imaging dispersive Raman spectrograph was configured to work at 830 nm laser excitation and was used to determine whether the composition of thin films of plastic explosives or small (e.g., ≤10 μm) particles of RDX or other explosives or oxidizers can be detected, identified, and quantified in the field. With 300 mW excitation energy, concentrations of RDX and PETN can be detected and reconstructed in the case of thin Semtex smears, but further work is needed to push detection limits of areal dosages to the ~1 μg/cm2 level. We describe the performance of several probe/spectrograph combinations and show preliminary data for particle detection, calibration and detection linearity for mixed compounds, and so forth.
Highlights
There is an ever increasing need for inexpensive and reliable detection of trace chemicals on surfaces for security and military applications [1]
Our work suggests that Offnerbased dispersive spectrographs using macro-lens coupling designs will permit wide line laser-illumination, yet offer efficient recovery of Raman backscattering that can help view large areas at low magnification
A comparison of the prototype Raman response to the FTRaman data is presented in Figure 5; again the Fourier transform (FT)-Raman data were acquired with 300 mW of excitation power, and with averaging times of several minutes compared to a 20 scan summation of 1 s exposures for the prototype dispersive system
Summary
There is an ever increasing need for inexpensive and reliable detection of trace chemicals on surfaces for security and military applications [1]. Raman spectroscopy, in the visible and near-infrared (NIR) wavelengths, has emerged as a method to detect and identify materials in a rapid and inexpensive manner [2]. Often the analyte Raman spectra can be and quickly interpreted in terms of peak height and/or peak area comparisons with an appropriate database [2]. As a consequence, identifying the provenance of materials, especially explosives, becomes more straightforward. Raman spectroscopy has transitioned from the research laboratory to a field analytical technique since it can rapidly detect and identify, with the use of an appropriate spectral database, thousands of chemicals including weapons of mass destruction materials [2]. Especially those developed to study residual energetic materials, continue to evolve, becoming smaller, more reliable and lower in cost [4, 5]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call