In this paper, we demonstrate the feasibility of microwave holographic imaging application based on spintronic microwave sensors. By adapting the rapid phase detection technique, a magnetic tunnel junction can achieve a real-time measurement of both the amplitude and phase of the scattered microwave using a lock-in amplifier. The built system has a capability to detect not only the existence of the concealed objects but also their shapes, allowing the concealed threat to be distinguished along with other hidden objects. The system is also able to estimate the distance of target by a broadband measurement. Anticipating the phase-detection of the dielectric function of the targets, we have also carried out extensive density functional theory calculations for a number of condensed phase energetic materials to determine their dielectric response in the microwave range.
Recently, preliminary experimental results of solar-to-hydrogen generation by wafer level InGaN nanowires were
reported [Z. Mi et al. Nano Lett., 2011, 11 (6), pp 2353-2357]. In the present paper we report a theoretical investigation
on the dissociation process of water molecules on wurtzite GaN (100) surface (M-Plane) using the density functional
theory (DFT). We calculated the structure and energetic of the water adsorption, reaction barrier energies and pathway
for water dissociation. The results suggest that the absorption of H2O is more favorable near Gallium atoms than near
Nitrogen atoms and we determined the likely binding sites of water molecules on GaN (100) surface. We also analyzed a
model for hydrogen evolution reaction on GaN (100) that involves three steps, where a water molecule first dissociates
into a hydrogen atom plus the OH group, followed by the dissociation of the hydroxyl group, and finally the two
hydrogen atoms recombine to form molecular hydrogen. For these reactions, the atomic positions and the reaction
barriers were determined.