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41.
42.
Matilda Vojnović Ana J. Šetrajčić-Tomić Siniša M. Vučenović Jovan P. Šetrajčić 《Optical and Quantum Electronics》2018,50(4):198
Recent research in nano-optical engineering and in nanomedicine as well, seeks for methods of construction of various types of nano-markers, nano-carriers, and ways to deliver drugs to the exactly determined regions of body. In this process it is important to find methods of recognition of certain types of molecules. It is obvious that optical recognition would be the easiest and the most effective way to do it. Our research presents a model of a molecular ultrathin crystalline film and generated exciton system inside it and corresponding methodology of analysis of their optical characteristics. Properties of these spatially very restricted structures are very sensitive to their surrounding surfaces. Using the two-time Green’s functions adapted for crystalline structures with symmetry breaking, and graphical-numerical software, we have calculated the energy spectra and possible exciton states. We have shown that the appearance and the presence of localized states on the surfaces and in the boundary layers of the film depend on the thickness of the film and the film surroundings, presented through the perturbation of parameters on surfaces. Optical properties in these structures demonstrate discrete and very selective resonant absorption spectra, depending on the perturbation on their surfaces. 相似文献
43.
Boris Rajčić Silvana B. Dimitrijević Marijana Petković Marija Nišavić Mario Cindrić Filip Veljković Suzana Veličković 《Optical and Quantum Electronics》2018,50(5):218
In this work, a simple way for study the possibility of formation a vapor cluster species of tetrachloroauric acid (HAuCl4), using the laser ablation in the absence of a buffer or reactive atmosphere, and without a postablation supersonic expansion on a commercial matrix assisted laser desorption/ionization time-of-flight mass spectrometer, is reported. Tetrachloroauric acid is known as precursor for the synthesis of gold nanostructures and the complex salts; therefore it is an important task to discover and quantify the species arising from HAuCl4, in order to understand their role in the gold assisted reactions. Mass spectrum of HAuCl4 in a reflector negative-ion mode contains the hydrated mono- and dinuclear gold clusters in the m/z range 286–436, and gold chloride clusters in the m/z range 447–795. In the first part of spectrum, m/z range 286–436, the hydrated gold cluster species of type Au n ? (H2O)m (n?=?1–2; m?=?1, 2, 5, 7, 8) and [Aun(OH)k]?(H2O)m (n?=?1–2; k?=?1–2; m?=?1, 4–8) were found. Besides that, there are gold chloride clusters with general formula [AuHr(HCl)2]?(H2O)m (m?=?1–5; 8–9; r?=?0–2) in this part of spectrum. In the second part of spectrum, the m/z range 447–795, only gold chloride clusters were obtained. Their general formulae can be written as [AuClt(HCl)v]?(H2O)m (t?=?1–4; v?=?5–8; m?=?2–4, 6–8) and [Aun(HCl)v]?(H2O)m (n?=?1–2, v?=?4–5, m?=?1–2, 5, 7). The analysis of concentration effects on the LDI mass spectra of gold clusters reveals that the relative intensities of signals for the mono- and dinuclear Au clusters increase with decreasing the concentration of water HAuCl4 solutions. 相似文献
44.
Marko Obradović Janez Kovač Suzana Petrović Vladimir Lazović Branislav Salatić Jovan Ciganović Dejan Pjević Momir Milosavljević Davor Peruško 《Optical and Quantum Electronics》2018,50(6):257
The possibility of interlayer mixing in a Ti/Ta multilayer system, induced by laser irradiation, was the main purpose of these experiments. Ti/Ta multilayer system, consisting of ten alternating Ti and Ta thin films and covered by slightly thicker Ti layer, was deposited on Si (100) wafers to a total thickness of 205 nm. Laser irradiation was performed in air by picoseconds Nd:YAG laser pulses in defocused regime with fluences of 0.057 and 0.11 J cm?2. Laser beam was scanned over the 5?×?5 mm surface area with different steps along y-axes. Structural and compositional characterisation was done by auger electron spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy. Laser processing at lower fluence caused only oxidation of the top Ti layer, despite of the number of applied laser pulses. Interlayer mixing was not observed. Application of laser pulses at fluence of 0.11 J cm?2 caused partial and/or complete ablation of deposited layers. In partially ablated regions considerable mixing between Ti and Ta films was registered. 相似文献
45.
46.
N. V. Veličko 《Georgian Mathematical Journal》1995,2(6):653-657
Some relations between cardinal invariants ofX andC(X) are established in the weak topology, whereC(X) is the space of continuous real-valued functions onX in the compact-open topology. 相似文献
47.
Giaimo JM Lockard JV Sinks LE Scott AM Wilson TM Wasielewski MR 《The journal of physical chemistry. A》2008,112(11):2322-2330
Perylene-3,4:9,10-bis(dicarboximide) (PDI) and its derivatives are robust organic dyes that strongly absorb visible light and display a strong tendency to self-assemble into ordered aggregates, having significant interest as photoactive materials in a wide variety of organic electronics. To better understand the nature of the electronics states produced by photoexcitation of such aggregates, the photophysics of a series of covalent, cofacially oriented, pi-stacked dimers and trimers of PDI and 1,7-bis(3',5'-di-t-butylphenoxy)perylene-3,4:9,10-bis(dicarboximide) (PPDI) were characterized using both time-resolved absorption and fluorescence spectroscopy. The covalent linkage between the chromophores was accomplished using 9,9-dimethylxanthene spacers. Placing n-octyl groups on the imide nitrogen atoms at the end of the PDI chromophores not attached to the xanthene spacer results in PDI dimers having near optimal pi-stacking, leading to formation of a low-energy excimer-like state, while substituting the more sterically demanding 12-tricosanyl group on the imides causes deviations from the optimum that result in slower formation of an excimer-like excited state having somewhat higher energy. By comparison, PPDI dimers having terminal n-octyl imide groups have two isomers, whose photophysical properties depend on the ability of the phenoxy groups at the 1,7-positions to modify the pi stacking of the PPDI molecules. In general, disruption of optimal pi-stacking by steric interactions of the phenoxy side groups results in excimer-like states that are higher in energy. The corresponding lowest excited singlet states of the PDI and PPDI trimers are dimer-like in nature and suggest that structural distortions that accompany formation of the trimers are sufficient to confine the electronic interaction on two chromophores within these systems. This further suggests that it may be useful to build into oligomeric PDI and PPDI systems some degree of flexibility that allows the structural relaxations necessary to promote electronic interactions between multiple chromophores. 相似文献
48.
Jozef?KurucEmail author Dávid?Harvan Du?an?Galanda L’ubomír?Mátel Monika?Jerigová Du?an?Veli? 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):611-615
Electrodeposited natural uranium films prepared by electrodeposition from solution of uranyl nitrate UO2(NO3)2·6H2O on stainless steel discs in electrodeposition cell. Solutions of NaHSO4, and Na2SO4 and electric current from 0.50 up to 0.75 A were used in this study. Recalculated weights and surface’s weights of 238U from the alpha activities and secondary ion mass spectrometry (SIMS) intensities resulted in a linear regression. A dependency
between of 238U surface’s weights recalculated from alpha activities and signal intensity of 238U in SIMS was investigated in order to determine a potential of SIMS in quantitative analysis of surface samples containing
uranium. In the SIMS spectra of electrodeposited uranium films we found that upper layer consist not only from isotopes of
uranium (ions 234U+, 235U+, and 238U+). In the positive polarity SIMS spectra, various molecules ions of uranium were suggested as UH+, UH2
+, UO+, UOH+, UO2
+, UO2H+, UO2H2
+, as well as possibly ions UNO+ and UNOH+. 相似文献
49.
Rates of convergence in certain limit theorem for extreme values 总被引:1,自引:0,他引:1
Pavle Mladenovi? Jovan Vukmirovi? 《Journal of Mathematical Analysis and Applications》2010,363(1):287-295
Let be independent random variables with the common negative binomial distribution with parameters r>0 and 1/n, where r is not necessarily an integer. We determine the limiting distribution of the random variable as n→∞, corresponding normalizing constants and the rate of convergence. For an integer r the connection with certain waiting time problems is indicated. 相似文献
50.
Dilute mixtures of n-octanal in synthetic air (up to 100 ppm) were photolyzed with fluorescent UV lamps (275-380 nm) at 298 K. The main photooxidation products were 1-hexene, CO, vinyl alcohol, and acetaldehyde. The photolysis rates and the absolute quantum yields were found to be slightly dependent on the total pressure. At 100 Torr, Φ(100) = 0.41 ± 0.06, whereas at 700 Torr the total quantum yield was Φ(700) = 0.32 ± 0.02. Two decomposition channels were identified: the radical channel C(7)H(15)CHO → C(7)H(15) + HCO and the molecular channel C(7)H(15)CHO → C(6)H(12) + CH(2)═CHOH, having absolute quantum yields of 0.022 and 0.108 at 700 Torr. The product CH(2)═CHOH tautomerizes to acetaldehyde. Carbon balance data lower than unities suggest the existence of unidentified decomposition channel(s) which substantially contributes to the photolysis. On the basis of experimental and theoretical evidence, n-octanal photolysis predominantly proceeds to form Norrish type II products as the major ones. 相似文献