ABSTRACT
This article presents a sensing technique to characterize the growth of an alumina passive film on an aluminum micro structured layer in situ. The technique uses surface plasmon resonance (SPR) on aluminum coated gratings with spectroscopic measurements during electrochemical polarization in 0.02M Na2SO4. The structure of the sensor was first simulated and then fabricated by photolithography. The grating was then replicated by nanoimprint (NIL) in Sol-Gel before pure aluminum layer was deposited by RF magnetron sputtering to produce the samples used in this study. Coupled plasmonic and electrochemical measurements confirmed the feasibility of in situ characterization (thickness) of alumina passive film on aluminum-based gratings in neutral aqueous media. Combining both measurements with an appropriated SPR spectrum fitting lead to alumina thickness monitoring within a few nanometers' accuracy. The objectives and challenges of this study are to better characterize the alumina growth during electrochemical process combining in situ electrochemical process and SPR spectra in order to determine thin passive layer characteristics.
ABSTRACT
Nanoporous carbon nanospheres <150 nm in diameter have been fabricated for the first time by the transformation of amorphous carbon nanospheres under Joule heating. The process, initiated by current densities of 1.5-8 × 10(10) A m(-2), has been imaged in real time in situ in a transmission electron microscope. Significant atomic diffusion and carbon ordering results in the formation of a 3D network of buckled graphitic sheets bounding interlinked <5 nm diameter pores, with greatly enhanced conductivity. Porous carbon nanospheres offer new opportunities for biocompatible drug delivery, catalysis and energy storage.
