RDX remote Raman detection on NATO SET-237 samples

Abstract

Ultraviolet Raman spectroscopy measurements have been taken at DLR in Lampoldshausen to detect NATO SET-237 standard samples of RDX. The main goal was to quantify the minimum requirements for an unambiguous identification in remote detection (60 cm distance) with a commercial Czerny–Turner spectrometer coupled with a CCD camera. Well-defined distribution of explosives on surfaces was tested as standardized samples. Therefore, Raman spectra of RDX have been acquired for different sample concentrations (50, 250 and 1000 μg/cm2, respectively) and under several laser energies (1.5, 3.0 and 5.0 mJ/pulse, respectively) at 355 nm excitation wavelength. The lowest possible reproducible surface concentration (50 µg/cm2) was detected with excitation energy of 3 mJ/pulse in the described configuration.

Explosives and warfare agents remote Raman detection on realistic background samples

“…A detailed description of this methodology is provided by Schnürer et al [14]. The new set of samples requested was in smaller concentration comparing the previous one prepared on 2019 [7]. Smaller concentrations (50, 30, 20, 10, 5 and 1 µg/cm 2 , respectively) were required to further test the sensitivity limits.…”

“…Native fluorescence was summing up to the room light adding extra disturbances. Native fluorescence can come from the measured compounds (in this case only from the warfare agents' simulants, since it was demonstrated that none of the tested explosives offered detectable fluorescence signal [7]) and from the substrates simultaneously. The fluorescence interference can play a very significant role since the lased-induced fluorescence (LIF) signal is much stronger than the Raman [1].…”

“…Raman spectroscopy was selected for its unique capability of being fast-responsive, highly sensitive, selective and able to identify different explosive compounds [3,4], precursors [5] and chemical warfare agents [6]. As previously demonstrated by Gallo et al [7], perhydro-1,3,5-trinitro-1,3,5-triazine (RDX) [8] was possible to be detected in the µg range at about 60 cm distance using well-defined homogeneous samples over an polished aluminum background. This work is a follow-up of that study.…”

“…This work is a follow-up of that study. In this new development, RDX and trinitrotoluene (TNT) [9] were tested again over new NATO-237 standard samples, prepared with lower concentrations with respect to the previous study [7] and used as reference. The purpose was to detect the minimum possible explosive amount over an ideal polished surface with a homogeneous distribution of the chemical under examination.…”

Quasi-CW Pumping of a Single-Frequency Fiber Amplifier for Efficient SHG in PPLN Crystals with Reduced Thermal Load

“…High-power single-frequency laser systems have become increasingly attractive thanks to their high spatial and temporal coherence, which has enabled technological advances in many applications such as high-resolution spectroscopy, remote sensing, non-linear frequency conversion, and holography. In particular, remote Raman spectroscopy [1,2] is witnessing increasing use, especially in military and defense applications, to detect and identify chemical, biological, radiological, nuclear, or explosive materials [3]. The Raman signal strength (intensity) is directly proportional to the power of the laser used to excite the sample, and inversely proportional to the laser wavelength [4].…”