Spin Properties of Germanium-Vacancy Centers in Bulk and Near-Surface Regions of Diamond

Germanium-vacancy (GeV) centers are now studied extensively due to perspectives of their applications in quantum information processing, nanometrology and nanoscale magnetic resonance imaging. One of the important requirements for these applications is a detailed understanding of the hyperfine interactions in such systems. Quantum chemistry simulation of the negatively charged GeV− color center in diamond is the primary goal of this paper in which we present preliminary results of computer simulation of the bulk H-terminated cluster C[Formula: see text][GeV−]H[Formula: see text], as well as of the surface cluster C[Formula: see text][GeV−]H[Formula: see text]_(100)_H[Formula: see text] having one dangling bond at (1 0 0) surface using the DFT/PW91/RI/def2-SVP level of theory.

Study on Influence of Silicon Crystal Dislocation on Removal in Atmospheric Pressure Plasma Polishing

Compared to perfect crystal lattice, typical edge dislocation structure has been modeled by quantum chemistry simulation in order to analyze the influence of crystal structure defects on removal process in atmospheric pressure plasma polishing (APPP). The Partial density of states (PDOS), number of states, average number of bonding electrons and energy have been calculated and analyzed further for these models. The analysis results reveal that silicon crystal with edge dislocation can be etched more easily than that of perfect crystal lattice. It is also found that the removal rate of sample with higher dislocation density is larger than that of lower dislocation density in the same experiment conditions. Thus, theoretical simulation demonstrates that structure dislocation is helpful for raising the etching rate, which accords well with testifying experiments results. But maybe structure dislocation could deteriorate surface roughness to some extent in initial stage of machining, as the dislocation structure is usually etched unevenly, although this is just a transition period.

Potassium Sulfate Nanoparticles in Water Solutions: Experiment and Quantum Chemistry Simulation

Pure potassium sulfate single crystals are transparent in a wide spectral range up to 155 nm and do not show fluorescence and absorption over a wide spectral range of 200-800 nm before and after X-ray irradiation of the samples. The centers of luminescence in thallium-doped potassium sulfate crystals showed a maximum absorption 216 nm and emission 285 nm at room temperature. These centers are singly charged thallium ions. It is interesting to research the optical properties with decreasing size of crystals (size effects). For this, we used a supersaturated aqueous solution of potassium sulfate, in which the crystallization begins. The results of computer simulations using Scigress quantum chemistry package show that the occurrence of macromolecules in a cooled supersaturated solution should result in an increased absorption. In supercooled saturated aqueous solutions of ionic crystals nucleation occurs. A decrease of transparency of saturated solutions with decreasing temperature is clearly seen. This is due to absorption and scattering in the medium with the growing small crystals in the solution.