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Cantu, Luca and Gallo, Emanuela and Duschek, Frank (2021) REMOTE RAMAN SCATTERING DETECTION OF EXPLOSIVES. ODAS (ONERA-DLR Aerospace Symposium) -MOTAR (Measurement and Optical Techniques for Aerospace Research) 2021, 14-16 June 2021, Paris, France. (Submitted)

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An experimental setup for remote ultraviolet Raman spectroscopy with short pulse systems was optimized for the investigation of explosives on contaminated surfaces. 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. First results were presented in this study to identify the detection limits (laser energy and compound’s concentration) for RDX (explosive agent of C-4). Well-defined distributions of explosives on surface were tested as standardized samples (NATO SET-237). 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 Raman signature of the explosive corresponds to the signature of the pure substance known from the literature. The minimum detectable RDX was 4.4 μg with exciting laser energy of 3.0 mJ/pulse. With this pulse energy, the signal to noise ratio was found too low for a clear identification, so 5.0 mJ/pulse are suggested to avoid false alarms. Increasing further the concentration of RDX (at least 89.7 µg) provided always a clear identification of the explosive material even with the lowest chosen laser energies of 1.5 mJ/pulse. A further optimization of the system (pulse energies and pulse diameter, collecting optics, detection device) is suggested and it will be examined in order to further decrease the detectable amount limits. Moreover, the preparation and description of a suitable sample plays an essential role in determining the sensitivities of the employed technologies. Their specified standard concentration (µg/cm2) is discussed by means of an effective detection sensitivity, especially in the case of inhomogeneous surfaces with thick sample particles of random sizes and optical detection techniques. The proposed estimation of the sensitivity relies on homogeneous layers with a thickness equal to the penetration depth of the exciting laser light.

Item URL in elib:https://elib.dlr.de/141626/
Document Type:Conference or Workshop Item (Speech)
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Cantu, LucaLuca.Cantu (at) dlr.deUNSPECIFIED
Gallo, EmanuelaEmanuela.Gallo (at) dlr.deUNSPECIFIED
Duschek, FrankFrank.Duschek (at) dlr.deUNSPECIFIED
Date:23 April 2021
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:Raman spectroscopy, explosives, C4, RDX, remote detection
Event Title:ODAS (ONERA-DLR Aerospace Symposium) -MOTAR (Measurement and Optical Techniques for Aerospace Research) 2021
Event Location:Paris, France
Event Type:international Conference
Event Dates:14-16 June 2021
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Optical remote sensing
Location: Lampoldshausen
Institutes and Institutions:Institute of Technical Physics > Atmospheric Propagation and Effect
Deposited By: Gallo, Ph.D. Emanuela
Deposited On:07 Apr 2021 10:01
Last Modified:07 Apr 2021 10:01

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