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Andrzej Kwiatkowski, Marcin Gnyba, Janusz Smulko and Paweł Wierzba

Algorithms of Chemicals Detection Using Raman Spectra

Raman spectrometers are devices which enable fast and non-contact identification of examined chemicals. These devices utilize the Raman phenomenon to identify unknown and often illicit chemicals (e.g. drugs, explosives) without the necessity of their preparation. Now, Raman devices can be portable and therefore can be more widely used to improve security at public places. Unfortunately, Raman spectra measurements is a challenge due to noise and interferences present outside the laboratories. The design of a portable Raman spectrometer developed at the Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology is presented. The paper outlines sources of interferences present in Raman spectra measurements and signal processing techniques required to reduce their influence (e.g. background removal, spectra smoothing). Finally, the selected algorithms for automated chemicals classification are presented. The algorithms compare the measured Raman spectra with a reference spectra library to identify the sample. Detection efficiency of these algorithms is discussed and directions of further research are outlined.

Open access

Bartłomiej Dec, Mateusz Ficek, Michał Rycewicz, Łukasz Macewicz, Marcin Gnyba, Mirosław Sawczak, Michał Sobaszek and Robert Bogdanowicz

Abstract

The main subject of this study are molecular structures and optical properties of boron-doped diamond films with [B]/[C]ppm ratio between 1000 and 10 000, fabricated in two molar ratios of CH4-H2mixture (1 % and 4 %). Boron-doped diamond (BDD) film on the fused silica was presented as a conductive coating for optical and electronic purposes. The scanning electron microscopy images showed homogenous and polycrystalline surface morphology. The Raman spectroscopy confirmed the growth of sp3 diamond phase and sp2carbon phase, both regular and amorphous, on the grain boundaries, as well as the efficiency of boron doping. The sp3/sp2ratio was calculated using the Raman spectra deconvolution method. A high refractive index (in a range of 2.0 to 2.4 at λ= 550 nm) was achieved for BDD films deposited at 700 °C. The values of extinction coefficient were below 1.4 at λ= 550 nm, indicating low absorption of the film

Open access

Maciej J. Głowacki, Marcin Gnyba, Paulina Strąkowska, Mateusz Gardas, Maciej Kraszewski, Michał Trojanowski and Marcin R. Strąkowski

Abstract

Hydroxyapatite (HAp) has been attracting widespread interest in medical applications. In a form of coating, it enables to create a durable bond between an implant and surrounding bone tissues. With addition of silver nanoparticles HAp should also provide antibacterial activity. The aim of this research was to evaluate the composition of hydroxyapatite with silver nanoparticles in a non-destructive and non-contact way. For control measurements of HAp molecular composition and solvent evaporation efficiency the Raman spectroscopy has been chosen. In order to evaluate dispersion and concentration of the silver nanoparticles inside the hydroxyapatite matrix, the optical coherence tomography (OCT) has been used. Five samples were developed and examined ‒ a reference sample of pure HAp sol and four samples of HAp colloids with different silver nanoparticle solution volume ratios. The Raman spectra for each solution have been obtained and analyzed. Furthermore, a transverse-sectional visualization of every sample has been created and examined by means of OCT.