Fast and safe detection of sensitive explosives via pulsed Raman spectroscopy

Abstract

Raman spectroscopy is one of the most established methods for the rapid and reliable detection of explosives and other hazardous chemicals. It enables first responders to identify suspicious substances quickly and remotely, avoiding direct contact with potentially dangerous or explosive substances. Present systems available on the market nowadays are small and light enough for mobile use in many applications. However, the measurement of dark coloured substances like black powder or other sensitive explosives harbours the risk of ignition. This is particularly the case if the measurement spot is not changed during the procedure. High absorption of the laser energy usually leads to a strong heat development in the analysed material, leading to decomposition or even ignition of the substance. To overcome this challenge, this work focuses on experiments with a pulsed nanosecond laser with optimized repetition rate and beam fluence. Different sensitive explosive materials such as triacetone triperoxide (TATP), black powder and mixtures of both are irradiated with pulsed laser light to perform raman analyses. Results show the capability of the presented method to obtain high quality spectra in short measurement times without any observed ignition of the sensitive explosive material. In addition, the influence of ambient light on the detection performance is evaluated and can be minimised. Further efforts are being made to miniaturise the entire laboratory setup in order to take first steps towards the development of a portable device.