• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.322-329
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• 2007

The interaction of oxygen with the ordered $Ni_3Al(111)$ alloy surface at 800 K and 1000 K has been investigated using LEED, STM, HREELS, UPS, and PAX. The clean $Ni_3Al(111)$ surface exhibits a "$2{\times}2$" LEED pattern corresponding to the ordered bulk-like terminated surface structure. For an adsorption of oxygen at 800 K, LEED shows an unrelated oxygen induced superstructure with a lattice spacing of $2.93\;{\AA}$ in addition to the ($1{\times}1$) substrate spots. The combined HREELS and the UPS data point to an oxygen chemisorption on threefold aluminum sites while PAX confirms an islands growth of the overlayer. Since such sites are not available on the $Ni_3Al(111)$ surface, we conclude the buildup of an oxygen covered aluminum overlayer. During oxygen exposure at 1000 K, however, we observe the growth of ${\gamma}'-Al_2O_3$ structure on the reordered $Ni_3Al(111)$ substrate surface. This structure has been identified by means of HREELS and STM. The HREELS data will show that at 800 K the oxidation shows a very characteristic behavior that cannot be described by the formation of an $Al_2O_3$ overlayer. Moreover, the STM image shows a "Strawberry" structure due to the oxide islands formation at 1000 K. Conclusively, from the oxygen interaction with $Ni_3Al(111)$ alloy surface at 800 K and 1000 K an islands growth of the aluminum oxide overlayer has been found.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.97-102
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• 2018

In this work, the surface of gold nanoparticles (AuNPs) was modified with small molecules including mercaptoundecanoic acid (MUA) and L-lysine for the development of highly sensitive lateral flow (LF) sensors. Uniformly sized AuNps were synthesized by a modified Turkevich-Frens method, showing an average size of $16.7{\pm}2.1nm$. Functionalized AuNPs were then characterized by transmission electron microscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The stable conjugation of AuNPs and antibodies was obtained at pH 7.07 and the antibody concentration of $10{\mu}g/mL$. The functionalized AuNP-based LF sensor exhibited lower detection limit of 10 ng/mL for hepatitis B surface antigens than that of using the bare AuNP-based LF sensor (100 ng/mL).