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Instantaneous identification of hazardous explosive-related materials using laser induced photoacoustic spectroscopy

Yasser H. El-Sharkawy, Sherif Elbasuney, Ashraf El-sherif, Mohamed Eltahlawy, H.S. Ayoub
Trends in analytical chemistry 2018 v.106 pp. 151-158
acoustics, algorithms, ammonium nitrate, ammonium perchlorate, fertilizers, photoacoustic spectroscopy, urea nitrate
Common fertilizers have the oxidizing and the reducing elements on the same molecule; therefore they have an explosiveness nature. Reliable approach for fast recognition of such compounds is an urgent need. Laser induced photoacoustic spectroscopy is an interesting technology as it can offer characteristic thermal, acoustical, and light absorption coefficient. The paper deals with a photoacoustic spectroscopy technique to record the characteristic photoacoustic frequency-response of common explosive-related materials. The proper stimulating light was generated using pulsed Q-switched Nd:YAG laser at 1064 nm. Photoacoustic signature for each investigated material was recorded using high response piezoelectric transducer. The captured signal was processed using novel digital algorithm designed for time and frequency domain analysis to achieve good discrimination between different explosive-related materials. Each investigated material demonstrated a characteristic absorption coefficient as well as frequency response with maximum amplitude at 47.9, 49, and 46 MHz for urea nitrate, ammonium nitrate, and ammonium perchlorate respectively.