| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF-ThP |
| Session: | Thin Films Poster Session |
| Presenter: | Sarka Havlova, University of Chemistry and Technology Prague, Czech Republic |
| Authors: | S. Havlova, University of Chemistry and Technology Prague, Czech Republic P. Fitl, University of Chemistry and Technology Prague, Czech Republic M. Vrnata, University of Chemistry and Technology Prague, Czech Republic E. Maresova, University of Chemistry and Technology Prague, Czech Republic J. Vlcek, University of Chemistry and Technology Prague, Czech Republic D. Tomecek, University of Chemistry and Technology Prague, Czech Republic J. Herbst, University of Chemistry and Technology Prague, Czech Republic |
| Correspondent: | Click to Email |
In this work, we present optical gas sensors with thin film of polymer as an active layer for the detection of taggants in explosives. The thin films of polymeric active layers based on poly(methyl methacrylate) (PMMA), polystyrene (PS) and low density polyethylene (LDPE) were prepared on lapped silicon substrates by spin coating with thicknesses in a range of hundreds nanometers (100 - 500 nm). These films were exposed to taggants' vapors such as 2-nitrotoluene (2-NT), 4-nitrotoluene (4-NT) and 2,3-dimethyl-2,3-dinitrobutane (DMNB) and measured in a range of their concentration 1 - 1000 ppm. Changes of refractive index were observed compared to reference atmosphere - synthetic air. The change of refractive index and layer thickness appears due to a swelling of the polymeric film in present of analyte vapors.
Thin films of polymers were subsequently doped with organic luminescent agents (metal phthalocyanines) and inorganic nanoparticles of rare earths (holmium oxide) and prepared with similar thicknesses. Soluble sulphonated metal phthalocyanines were dissolved and mixed with polymer solution, thin films were then prepared by spin coating. Insoluble phthalocyanines were evaporated under high vacuum conditions on the top of polymeric layer and localized laser melting of polymer was used for submerging of phthalocyanine molecules into the polymer matrix. These luminescent films were also exposed to vapors of taggants and changes in UV-VIS absorption spectra and luminescence spectra were detected. The influence of toluene was also evaluated for a comparison of detection properties with a substance similar to selected taggants.
The results suggest that gas sensors with these sensitive layers and based on connected optical techniques such as a measurement of luminescence, absorption and refractive index are very promising for the detection of taggants in explosives.