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Indium nitride is one of the very few semiconductors which is known to have a superconducting phase at temperatures of Tc > 1 K. Superconductivity occurs in a window of carrier densities of approximately  1018–1020 cm−3. This is a very low density when compared to other superconductors (i.e. metals, alloys, high Tc oxides) and thus raises interesting fundamental questions as well as technological possibilities. In this paper we address one key question about the dimensionality of the superconducting state of InN by using angle dependent critical field measurements. Our samples were grown by two different growth techniques (chemical vapour deposition and plasma-assisted molecular beam epitaxy) on c-oriented sapphire, with and without a GaN buffer layer. In both cases we find that for film thicknesses much larger than the coherence length d ≫ ξ, the angle dependence of the critical field (down to T < 280 mK) with respect to the c-axis continues to be clearly two-dimensional, demonstrating a characteristic cusp when the angle crosses 90° with respect to the c-axis. This indicates that the superconducting electrons are most likely confined to a layer much thinner than the thickness of the InN film. Further we find the magnitude of the gap to be 2Δ(0)/kBTc = 3.6, very close to the BCS prediction.

The quenching of the fluorescence of 1-aminopyrene (1-Ap) by reduced graphene oxide (rGO) has been investigated using spectroscopic techniques. In spite of the upward curvature in the Stern-Volmer plot, the unchanged spectral signature of the absorption of 1-Ap in the presence of rGO and the decrease in fluorescence lifetime with increasing rGO concentration point toward the dynamic nature of the quenching. Detailed analysis of steady state and time-resolved spectroscopic data has shown that the quenching arises due to the photoinduced electron transfer from 1-Ap to rGO. This is again supported by estimating the Gibb's free energy change for the ground as well as excited state electron transfer. Ab initio calculations under the density functional theory (DFT) formalism reveal that the possibility of π-π stacking is very slim in the 1-Ap-rGO system and the electron density resides completely on 1-Ap in the highest occupied molecular orbital (HOMO) and on graphene in the lowest unoccupied molecular orbital (LUMO), supporting the experimental findings of the intermolecular electron transfer between 1-Ap and rGO in the excited state.

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