Surface ionization study of the non- stoichiometric LnFn-1 (n = 4 – 6) clusters

In this study we are presenting the results of the surface ionization of LinFn-1 (n=4- 6) clusters on rhenium surface impregnated with fullerenes using the magnetic mass spectrometer. The Li5F4 nanocubic cluster was detected for the first time. We determined values of ionization energies for Li4F3 and Li6F5, they are 4,3±0,2 eV, 4,0±0,2eV, respectively. The ionization energies agreed with theoretical ionization energies obtained by ab initio method, which indicates the excess electron localized in a specific site for non-stoichiometric clusters. The first ionization energy value for the Li4F3 was in accordance with earlier results obtained experimentally using photoionization time-of-flight mass spectrometer. There are currently no reliable experimental data for the ionization energy of Li6F5 cluster.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Study of the vaporization of LiI, LiI/C-70, LiI/LiF/C-70 from a Knudsen cell located in the ionization chamber of a mass spectrometer

The vaporization of LiI, LiI/C-70 and LiI/LIF/C-70 was studied using a Knudsen cell located in the ionization chamber of a magnetic sector mass spectrometer in the temperature range from 350 degrees C to 850 degrees C. The ion species, LinI+ (n = 2, 3, 4 or 6) were identified from the mixture LiI/C-70, while the clusters LinI+ and LinF+ (n = 2, 3, 4, 5 or 6) were detected from a mixture LiI/LiF/C-70. The intensities of LinI+ were higher than the emission of LinF+ cluster when the ratio of LiI to LiF was 2:1. By contrast, the emission of LinF+ is favored when the ratio of LiI to LiF was 1:2. These results show that the vaporization of a mixture LiI/LIF/C-70 from a Knudsen cell located in the ionization chamber of a mass spectrometer represents an efficient and simple way to obtain and investigate clusters of the type LinX, X = F or I. In this work, it was also shown that the trends of the In (Intensity, arb. units) versus temperature for all LinI+ clusters below and above the melting point of LiI were not same. This suggested that the manner of formation of these clusters could be different due to changes in temperature

Fractal nature Heywang model contribution and BaTiO3-ceramics semiconducting phenomena

Well known material with ferroelectric properties, BaTiO3-ceramics, have many advanced applications. Fractal approach in analyzing of these structures can be one of the solution for investigation of morphology. It is known that a wide range of disordered systems can be characterized by the fractal nature over a microscopic correlation length, and on a small scale the energy transformations are permitted. Due to the lack of energy, priorities of the future frontiers in ceramics science is to expand the knowledge even down to nano and towards new and alternative energy sources. Fractal configuration nature of BaTiO3 and other ceramics is based on phenomena that ceramic grains have fractal shape; there are pores and inter-granular space and there is particles Brownian fractal motion inside the material, during and after sintering, in the form of micro-particles flow, which is the most important. These important facts are in function of further developing of knowledge of energy harvesting and storage

Modeling the thermal and electrical conductivity relation of synthesized diamonds within fractal nature analysis

Improvement of novel materials could be very good development base for enhancement of new technologies. One of the most promising material of modern science is undoubtedly synthesized diamond. Because of variety of modern applications, the research in this area is becoming intensive. Utilization of this material made great step forward in many areas, beside the most known jewelry, also in producing microcomponents, in medical-surgery, as well as in high professional industry. These and others specific application of polycrystal diamonds, require permanently research and improvement of their properties. Although, the first synthesized diamond was created half a century ago using high pressure - high temperature (HPHT) method, diamonds created by chemical vapor deposition (CVD) method were much more convenient for application in so many areas. By applying CVD method, microcrystalline diamond (MCD) with grain size approximately 100 nm were created. Due to some disadvantages of MCD films, like values of hardness and Young’s modulus, new nanocrystalline (NCD) and ultra-nanocrystalline (UNCD) diamond materials were developed, with average grains size of 5-100 nm and 3-5 nm, respectively. The properties of polycrystalline diamonds can vary depending on the consolidation process like composition and pressure of applied gases, filament setup and reactor geometry. In that sense, changing the parameters of consolidation process, there is a possibility to change the microstructure of thin films and understanding its fundamentals. Also, fractal nature analysis could contribute to the revealing possibilities for improvement of polycrystalline diamond films. During carried out experiments, it was observed that there is the influence of grain size on thermal and electrical conductivity - when the thermal conductivity is increasing then electro conductivity is decreasing and opposite. Relation between the structures and final properties of synthetized diamonds can be achieved by explaining these phenomena based on fractal nature

Tims and maldi tof of endohedral 99mTc@C60 metallofullerene

Mass spectral studies (both TIMS – thermal ionization and MALDI TOF – matrixassisted laser desorption time-of-flight mass spectrometry) of the endohedral metallofullerenes, 99mTc@C60 and 99mTc@C70, provided detailed structural and reactivity information about these unusual species. MS experiment revealed that both fullerenes and endohedral metallofullerenes fragment by multiple C2 loss. However, a difference in the terminal fragmentation products was observed for metallofullerene relative to C60, suggesting that the encapsulation metal strongly impacts the fragmentation product. Singly charged cations of the metallofullerenes (M@Cn + ) were completely unreactive in the gas phase with oxygenated compounds such as ethylene oxide: however, the corresponding neutral species appear to react readily with oxygenated species. Collisional dissociation of the ionized endohedral fullerenes listed above revealed multiple C2 loss (either as sequential C2 loss or larger C2n eliminations) to generate similar terminal fragmentation products, which might be predicted due to the similar ionic radii of the encapsulated metals. The observed ionization energies of endohedral molecules were, 5.1 ± 0.1 eV and 5.3 ± 0.1 eV, respectively.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Supplementary data for article: Đokić-Stojanović, D. R.; Todorović, Z. B.; Troter, D. Z.; Stamenković, O. S.; Veselinović, L. M.; Zdujić, M. V.; Manojlović, D. D.; Veljković, V. B. Triethanolamine as an Efficient Cosolvent for Biodiesel Production by Cao-Catalyzed Sunflower Oil Ethanolysis: An Optimization Study. Hemijska Industrija 2019, 73 (6), 351–362. https://doi.org/10.2298/HEMIND190822033D

Supplementary material for: [https://doi.org/10.2298/HEMIND190822033D]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3797

Triethanolamine as an efficient cosolvent for biodiesel production by cao-catalyzed sunflower oil ethanolysis: An optimization study

Triethanolamine was applied as an efficient „green“ cosolvent for biodiesel production by CaO-catalyzed ethanolysis of sunflower oil. The reaction was conducted in a batch stirred reactor and optimized with respect to the reaction temperature (61.6-78.4 °C), the ethanol-to-oil molar ratio (7:1-17:1) and the cosolvent loading (3-36 % of the oil weight) by using a rotatable central composite design (RCCD) combined with the response surface methodology (RSM). The optimal reaction conditions were found to be: the ethanol-to-oil molar ratio of 9:1, the reaction temperature of 75 °C and the cosolvent loading of 30 % to oil weight, which resulted in the predicted and actual fatty acid ethyl ester (FAEE) contents of 98.8 % and 97.9±1.3 %, respectively, achieved within only 20 min of the reaction. Also, high FAEE contents were obtained with expired sunflower oil, hempseed oil and waste lard. X-ray diffraction analysis (XRD) was used to understand the changes in the CaO phase. The CaO catalyst can be used without any treatment in two consecutive cycles. Due to the calcium leaching into the product, an additional purification stage must be included in the overall process.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3798

Supplementary data for article: Đokić-Stojanović, D. R.; Todorović, Z. B.; Troter, D. Z.; Stamenković, O. S.; Veselinović, L. M.; Zdujić, M. V.; Manojlović, D. D.; Veljković, V. B. Triethanolamine as an Efficient Cosolvent for Biodiesel Production by Cao-Catalyzed Sunflower Oil Ethanolysis: An Optimization Study. Hemijska Industrija 2019, 73 (6), 351–362. https://doi.org/10.2298/HEMIND190822033D

Supplementary material for: [https://doi.org/10.2298/HEMIND190822033D]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3797

Phonon-induced spin relaxation of conduction electrons in aluminum

Spin-flip Eliashberg function $\alpha_S^2F$ and temperature-dependent spin relaxation time $T_1(T)$ are calculated for aluminum using realistic pseudopotentials. The spin-flip electron-phonon coupling constant $\lambda_S$ is found to be $2.5\times 10^{-5}$. The calculations agree with experiments validating the Elliott-Yafet theory and the spin-hot-spot picture of spin relaxation for polyvalent metals.Comment: 4 pages; submitted to PR

Influence of various cosolvents on the calcium oxide-catalyzed ethanolysis of sunflower oil

Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-hexane, triethylamine, ethylene glycol dimethyl ether, glycerol, tetrahydrofuran and dioxane) were applied as cosolvents in the CaO-catalyzed ethanolysis of sunflower oil performed in a batch stirred reactor under the following reaction conditions: temperature 70 °C, ethanol-to-oil mole ratio 12:1, initial catalyst concentration 1.374 mol·L -1 and amount of cosolvent 20 % based on the oil amount. The main goals were to assess the effect of the used cosolvents on the synthesis of fatty acid ethyl esters (FAEE) and to select the most efficient one with respect to the final FAEE content, reaction duration and safety profile. In the absence of any cosolvent, the reaction was rather slow, providing a FAEE content of only 89.7±1.7 % after 4 h. Of the tested cosolvents, diethanolamine, triethanolamine and ethylene glycol significantly accelerated the ethanolysis reaction, whereby the last two provided a final FAEE content of 93.1±2.1 and 94.1±1.5 %, respectively, within 0.5 h. However, because of its safety profile, triethanolamine was selected as the best cosolvent for the ethanolysis of sunflower oil catalyzed by calcined CaO