Search

Low energy Ag ions were implanted into silicon and annealed at different temperatures in order to generate plasmonic active silicon hybrids. It was found that as the ion fluence of irradiation was increased, a monotonic decrease in the absorption spectra in the ultraviolet region occurs, due to amorphization and macrostructuring of the Si surface. At the same time, the optical spectra are characterized by a strong band after implantation presenting the contribution of the surface plasmon resonance (SPR) of Ag nanoparticles. After heat treatment at 500 and 600ºC, the SPR peak shifts to lower wavelengths, as compared to as implanted samples, whereas the plasmon position shifts to higher wavelengths for annealing at 700°C. This observation can be explained by either an out-diffusion of Ag or by stress relaxation and recrystallization of silicon. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45005]

The present study deals with CrN films irradiated at room temperature (RT) with 200 keV Ar+ ions. The CrN layers were deposited by d.c. reactive sputtering on Si (100) wafers, at nitrogen partial pressure of 5×10-4 mbar, to a total thickness of 280 nm. The substrates were held at 150ºC during deposition. After deposition the CrN layers were irradiated with 200 keV Ar+ ions to the fluences of 5×1015 - 2×1016 ions/cm2. Structural characterization was performed with Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM) and X-ray diffraction (XRD). Spectroscopic ellipsometry measurements were carried out in order to study optical properties of the samples. The irradiations caused the microstructrual changes in CrN layers, but no amorphization even at the highest argon fluence of 2×1016 ions/cm2. Observed changes in microstructure were correlated with the variation in optical parameters. It was found that both refractive index and extinction coefficient are strongly dependent on the defect concentration in CrN layers. [Projekat Ministarstva nauke Republike Srbije, br. III 45005]

Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5-7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO(2) into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence.

Introduction: The concern is present worldwide as the tobacco use and smoking is becoming more and more common in young generation. Spread of tobacco use epidemics is a global problem with serious consequences to social, economic and ecological life a well as on health., Objective: To collect information about tobacco use in students aged 13-15 years in school in Subotica, their knowledge and standing about smoking as well as level of advertisement and availability of purchasing tobacco and tobacco products. It should include the level of passive smoking, i.e. exposure to tobacco smoke and health education in curriculum., Method: Application of statistical study involving 327 students aged 13-15 years in 4 elementary and 2 high schools in Subotica, in October 2003. "Global youth tobacco survey" was the statistical study that was used after required permits had been granted., Results: A total of 41.5% of students tried cigarette smoking, more girls (43.4%) than boys (38.6%; p > 0.05); 52.6% of first grade of high school students, 37.6% of eighth grade and 33.9% seventh grade students (X2 = 9.081; DF = 2; p < 0.05). 7.4% students were regular smokers, and 14.8% smoked at least 3 weeks in the last month. Knowledge of students about the harmful effect of smoking was not satisfactory. Advertisement of tobacco product is highly present in media, and cigarettes are available easily. The level of passive smoking was also very high: 24.8% of parents were smokers, i.e. fathers accounted for 23.2%, and mothers accounted for 17% of cases. 28.7% of teachers smoked in school building. Educational and health programs in the schools are not satisfactory., Conclusion: The research shows that the use of tobacco products in student population is serious. It seems necessary to make an effective program which will control the use of tobacco products in early age of student population.