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Alloy nanoparticles due to their possibility of regulation, the region of absorption peak and consequently their optical and electrical properties, have a specific significance. In this research, nanosecond laser pulses of Nd:YAG laser with 532 nm wavelength that is close to absorption peak of gold and zinc nanoparticles, were used for synthesis of alloy. Atomic absorption spectrum UV-Visible, X-ray diffraction analysis and transmission electron microscopy images were utilized for characterization as well. For synthesis of Au-Zn alloy nanoparticles, zinc and gold nanoparticles were prepared separately by laser ablation method and then the mixture of their colloidal solutions with specified ratio was exposed to laser radiation. Thereby, gold and zinc nanoparticles were combined by absorbing of laser beam and gaining of required energy for melting, and Au-Zn alloy nanoparticles were formed. Wavelength of 532 nm is more effective in the formation of alloy than 1064 nm because of being close to wavelength of surface plasmon resonance of gold and zinc nanoparticles. Increase of concentration of gold nanoparticles compared to zinc nanoparticles in the mixed solution causes that gold nanoparticles absorb the most of the energy of laser and then larger gold particles are created, so alloy nanoparticles are not formed. The best time duration for irradiation and accomplishment of alloy formation is 30 min.

Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) images of graphene reveal either a triangular or honeycomb pattern at the atomic scale depending on the imaging parameters. The triangular patterns at the atomic scale are particularly difficult to interpret, as the maxima in the images could be every other carbon atom in the six-fold hexagonal array or even a hollow site. Carbon sites exhibit an inequivalent electronic structure in HOPG or multilayer graphene due to the presence of a carbon atom or a hollow site underneath. In this work, we report small-amplitude, simultaneous STM/AFM imaging using a metallic (tungsten) tip, of the graphene surface as-grown by chemical vapor deposition (CVD) on Cu foils. Truly simultaneous operation is possible only with the use of small oscillation amplitudes. Under a typical STM imaging regime the force interaction is found to be repulsive. Force–distance spectroscopy revealed a maximum attractive force of about 7 nN between the tip and carbon/hollow sites. We obtained different contrast between force and STM topography images for atomic features. A honeycomb pattern showing all six carbon atoms is revealed in AFM images. In one contrast type, simultaneously acquired STM topography revealed hollow sites to be brighter. In another, a triangular array with maxima located in between the two carbon atoms was acquired in STM topography.

We performed nanomachining combined with photoluminescence spectroscopy to understand the depth distribution of nitrogen-vacancy (NV) centers formed by low energy nitrogen ion irradiation of the diamond surface. NVand NV 0 fluorescence signals collected from the surface progressively machined by a diamond tip in an atomic force microscope (AFM) initially rise to a maximum at 5 nm depth before returning to background levels at 10 nm. This maximum corresponds to the defect depth distribution predicted by a SRIM simulation using a 2.5 keV