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Localized surface plasmon absorption features arise at high doping levels in semiconductor nanocrystals, appearing in the near-infrared range. Here we show that the surface plasmons of tin-doped indium oxide nanocrystal films can be dynamically and reversibly tuned by postsynthetic electrochemical modulation of the electron concentration. Without ion intercalation and the associated material degradation, we induce a > 1200 nm shift in the plasmon wavelength and a factor of nearly three change in the carrier density.

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Dense LLZO (Al-substituted Li7La3Zr2O12) pellets were processed in controlled atmospheres to investigate the relationships between the surface chemistry and interfacial behavior in lithium cells. Laser induced breakdown spectroscopy (LIBS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, synchrotron X-ray photoelectron spectroscopy (XPS) and soft X-ray absorption spectroscopy (XAS) studies revealed that Li2CO3 was formed on the surface when LLZO pellets were exposed to air. The distribution and thickness of the Li2CO3 layer were estimated by a combination of bulk and surface sensitive techniques with various probing depths. First-principles thermodynamic calculations confirmed that LLZO has an energetic preference to form Li2CO3 in air. Exposure to air and the subsequent formation of Li2CO3 at the LLZO surface is the source of the high interfacial impedances observed in cells with lithium electrodes. Surface polishing can effectively remove Li2CO3 and dramatically improve the interfacial properties. Polished samples in lithium cells had an area specific resistance (ASR) of only 109 Ω cm(2) for the LLZO/Li interface, the lowest reported value for Al-substituted LLZO. Galvanostatic cycling results obtained from lithium symmetrical cells also suggest that the quality of the LLZO/lithium interface has a significant impact on the device lifetime.

The manipulation of the bandgap of graphene by various means has stirred great interest for potential applications. Here we show that treatment of graphene with xenon difluoride produces a partially fluorinated graphene (fluorographene) with covalent C-F bonding and local sp(3)-carbon hybridization. The material was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, electron energy loss spectroscopy, photoluminescence spectroscopy, and near edge X-ray absorption spectroscopy. These results confirm the structural features of the fluorographane with a bandgap of 3.8 eV, close to that calculated for fluorinated single layer graphene, (CF)(n). The material luminesces broadly in the UV and visible light regions, and has optical properties resembling diamond, with both excitonic and direct optical absorption and emission features. These results suggest the use of fluorographane as a new, readily prepared material for electronic, optoelectronic applications, and energy harvesting applications.

The reduction potentials of five organic carbonates commonly employed in lithium battery electrolytes, ethylene carbonate ͑EC͒, propylene carbonate ͑PC͒, diethyl carbonate ͑DEC͒, dimethyl carbonate ͑DMC͒, and vinylene carbonate ͑VC͒ were determined by cyclic voltammetry using inert ͑Au or glassy carbon͒ electrodes in tetrahydrofuran/LiClO 4 supporting electrolyte. The reduction potentials for all five organic carbonates were above 1 V ͑vs. Li/Li ϩ ͒. PC reduction was observed to have a significant kinetic hindrance. The measured reduction potentials for EC, DEC, and PC were consistent with thermodynamic values calculated using density functional theory ͑DFT͒ assuming one-electron reduction to the radical anion. The experimental values for VC and DMC were, however, much more positive than the calculated values, which we attribute to different reaction pathways. The role of VC as an additive in a PC-based electrolyte was investigated using conventional constant-current cycling combined with ex situ infrared spectroscopy and in situ atomic force microscopy ͑AFM͒. We confirmed stable cycling of a commercial li-ion battery carbon anode in a PC-based electrolyte with 5 mol % VC added. The preferential reduction of VC and the solid electrolyte interphase layer formation therefrom appears to inhibit PC cointercalation and subsequent graphite exfoliation.

The interaction of Li(+) with single and few layer graphene is reported. In situ Raman spectra were collected during the electrochemical lithiation of the single- and few-layer graphene. While the interaction of lithium with few layer graphene seems to resemble that of graphite, single layer graphene behaves very differently. The amount of lithium absorbed on single layer graphene seems to be greatly reduced due to repulsion forces between Li(+) at both sides of the graphene layer.

In this paper we investigate the behavior of iteratively decoded low-density paritycheck codes over the binary erasure channel in the so-called "waterfall region." We show that the performance curves in this region follow a very basic scaling law. We conjecture that essentially the same scaling behavior applies in a much more general setting and we provide some empirical evidence to support this conjecture. The scaling law, together with the error floor expressions developed previously, can be used for fast finite-length optimization.