Detection of Explosives and Fire Gases

The goal of security research is to develop novel technologies to ensure the security of citizens from threats while respecting fundamental human rights. Laser spectroscopic methods play an increasingly important role in the research of safety and security systems.

Application of spectroscopy includes both the identification and quantification of substances. In this context, vibrational spectroscopic techniques such as Raman spectroscopy, which provide high structural information content, are of particular interest. A great disadvantage in any application of Raman spectroscopy is low sensitivity caused by the inherent weak Raman process.

: Atomic force microscope (AFM) image of the self-made SERS surface

The sensitivity can be increased by up to 14 orders of magnitude by the Surface Enhanced Raman Scattering (SERS) effect. Therefore, it was possible to reach single-molecule detection. The SERS effect does mainly emerge at noble metals whose surface possesses a nanostructure. Due to the single-molecule detection and the prerequisite nanostructured surface, Surface Enhanced Raman Spectroscopy (SERS) is a true nanotechnology.

As a result of the high sensitivity, SERS is predestined for the analysis of explosives and hazardous gases as it provides the identification of trace amounts of substances.

The key impediment for the practical use of SERS-based sensors is the lack of robust and facile fabrication strategies for reproducible SERS substrates with large and stable Raman enhancement. Thus, the objective of the project “Evaluation of the Limits and Potentials of the Detection of Explosives by Surface Enhanced Raman Scattering” is to develop a device for the detection of explosives and hazardous gases based on SERS.

: Breadboarding for the detection of explosives

Within the project, low cost SERS-active substrates with high reproducibility were generated. The principle of the device is the re-sublimation of the explosives on the nanostructured SERS-substrate. The approach is in particular of interest for the detection of triacetone triperoxid (TATP), as several detection devices detect only conventional explosives, but fail to detect triacetone triperoxide.

: Chemical structure of triaceton triperoxid (TATP)

This highly explosive material can not only cause fatal explosions, it is also fairly easy to obtain. These characteristics have led to an increased usage of triacetone triperoxide in terrorist bombings.

The project is part of the network “Nanostructured Photonic Gas Sensors” short NanoSens (InnoNet 16 IN0463) supported by BMWi via VDI/VDE-IT.