Silver phthalocyanine thin films carrying gold, palladium and silver nanoparticles for detection of taggants in explosives

Publication date: Available online 31 October 2016
Source:Thin Solid Films
Author(s): D. Tomeček, P. Fitl, E. Marešová, J. Vlček, J. Hofmann, M. Vrňata
Our work deals with thin films of silver phthalocyanine (AgPc) combined with gold, palladium and silver nanoparticles. These films were applied for the indirect detection of 2-nitrotoluene which is used as a taggant in explosives. The films were deposited by an Organic Molecular Evaporation and a DC magnetron sputtering. The growth of metallic nanoparticles was continuously monitored through in-situ resistance measurements to detect the percolation threshold. We varied composition of the nanoparticles, their amount (the sputtered equivalent thickness was in the range from 1 to 50nm) and also the geometry of sensing layers: geometry i) bottom AgPc + top nanoparticles, geometry ii) top AgPc layer + bottom nanoparticles. The sensors with geometry i) exhibited good recovery capabilities, those with geometry ii) seemed to better preserve phthalocyanine sensing properties. For the best combination, the AgPc(50nm)/Au(10nm) sensor, its dc-response rose to the value of 373 for 190ppm of 2-nitrotoluene. This suggests that 2-nitrotoluene can be detected in the sub-ppm concentrations by these films.