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2. ToF-SIMS depth profiling of metal, metal oxide, and alloy multilayers in atmospheres of ▫$H_2$▫, ▫$C_2H_2$▫, CO, and ▫$O_2$▫Jernej Ekar, Peter Panjan, Sandra Drev, Janez Kovač, 2022, original scientific article Keywords: Ions, Layers, Mass spectrometry, Metals, Oxides, SIMS depth profiling H2 C2H2 CO and O2 atmosphere gas flooding cluster secondary ions matrix effect Published in DiRROS: 18.10.2023; Views: 329; Downloads: 148 Full text (8,02 MB) This document has many files! More... |
3. Recombination of oxygen atoms on the surface of oxidized polycrystalline nickel—temperature and pressure dependencesDomen Paul, Miran Mozetič, Rok Zaplotnik, Jernej Ekar, Alenka Vesel, Gregor Primc, Denis Đonlagić, 2023, original scientific article Abstract: The recombination of neutral oxygen atoms in the ground state on the oxidized nickel samples was studied experimentally in the range of pressures where the maximum density occurs in weakly ionized low-pressure oxygen plasma, i.e. between 40 and 200 Pa. The recombination coefficient was determined in the flowing afterglow. The source of oxygen atoms was plasma sustained in a quartz tube of inner diameter 4.7 mm by a microwave discharge in the surfatron mode. The recombination coefficient was determined in the afterglow chamber, which was a Pyrex tube with an inner diameter of 36 mm. The density of oxygen atoms in the afterglow chamber was varied by adjusting the discharge power, the gas flow, the pressure, and the position of a recombinator. Such flexibility of the experimental system enabled adjustment of the temperature of the oxidized nickel samples independently from the O-atom density in its vicinity or other parameters. The density of oxygen atoms in the afterglow chamber at various system parameters was determined by the Šorli method, which is reliable, and has an accuracy of about 20%. The recombination coefficient was determined by calorimetry. The coefficient was inversely proportional to the square root of the pressure and exponentially to the sample temperature. Systematic measurements performed at various pressures and temperatures enabled empirical formula, which were explained qualitatively by recombination kinetics.
Keywords: heterogenous surface recombination, recombination coefficient, nickel, nickel oxide, temperature Published in DiRROS: 30.08.2023; Views: 332; Downloads: 197 Full text (2,44 MB) This document has many files! More... |
4. Loss of oxygen atoms on well-oxidized cobalt by heterogeneous surface recombinationDomen Paul, Miran Mozetič, Rok Zaplotnik, Jernej Ekar, Alenka Vesel, Gregor Primc, Denis Đonlagić, 2023, original scientific article Abstract: Calorimetry is a commonly used method in plasma characterization, but the accuracy of the method is tied to the accuracy of the recombination coefficient, which in turn depends on a number of surface effects. Surface effects also govern the kinetics in advanced methods such as atomic layer oxidation of inorganic materials and functionalization of organic materials. The flux of the reactive oxygen atoms for the controlled oxidation of such materials depends on the recombination coefficient of materials placed into the reaction chamber, which in turn depends on the surface morphology, temperature, and pressure in the processing chamber. The recombination coefficient of a well-oxidized cobalt surface was studied systematically in a range of temperatures from 300 to 800 K and pressures from 40 to 200 Pa. The coefficient increased monotonously with decreasing pressure and increasing temperature. The lowest value was about 0.05, and the highest was about 0.30. These values were measured for cobalt foils previously oxidized with oxygen plasma at the temperature of 1300 K. The oxidation caused a rich morphology with an average roughness as deduced from atomic force images of 0.9 µm. The results were compared with literature data, and the discrepancy between results reported by different authors was explained by taking into account the peculiarities of their experimental conditions. Published in DiRROS: 25.08.2023; Views: 319; Downloads: 155 Full text (3,59 MB) This document has many files! More... |