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.

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.

In order to explore the similarity and difference between the absorbance calculated by the Mie theory (A Mie ) and the Maxwell-Garnett (MG) effective medium approximation (A MG ), both were calculated using the Drude dielectric function for a range of volume fractions f V and bulk plasma frequencies (ω P ). For each case, the optical path length L was adjusted such that f V * L was kept constant. In this way, the total volume of the absorbing material is kept constant, resulting in comparable absorbance values for all f V . The mean-square-difference (MSD) between A Mie and A MG is shown in Fig. S1.

Analysis of the transmittance and reflectance of transparent conducting oxide thin films and nanocrystal films can be accurately modeled using the Drude free electron theory to extract electrical transport properties if enough care is taken. However, several fits starting from different initial guesses are needed before confidence in the extracted Drude parameters can be obtained. Film thickness, optical carrier concentration, and optical carrier mobility can be reliably derived when using either a fully empirical or semiempirical model for the ionized impurity scattering. The results are in good agreement with those based on more arduous spectroscopic ellipsometry measurements. Furthermore, fitting the reflectance along with the transmittance reduces the uncertainty, but does not significantly affect the values of the extracted parameters.

Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for pulse length of 100 µs at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were taken with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target's racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic pre-sheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons' E × B drift velocity, which is about 10 5 m/s and shows structures in space and time.