Controlled doping of carbon nanotubes is elemental for their electronic applications. Here we report an approach to tune the polarity and degree of doping of single-walled carbon nanotubes via filling with nickelocene followed by encapsulated reactions. Using Raman, photoemission spectroscopy and transmission electron microscopy, we show that nickelocene molecules transform into nickel carbides, nickel and inner carbon nanotubes with reaction temperatures as low as 250 °C. The doping efficiency is determined for each chemical component. Synchronous charge transfer among the molecular components allows bipolar doping of the carbon nanotubes to be achieved in a broad range of ±0.0012 e(-) per carbon.

Transparent, highly percolated networks of regio-regular poly(3-hexylthiophene) (rr-P3HT) wrapped semiconducting single walled carbon nanotubes (s-SWNT) are deposited and the charge transfer processes of these nanohybrids are studied using spectroscopic and electrical measurements. The data discloses hole doping of s-SWNTs by the polymer, challenging the prevalent electron doping hypothesis. Through controlled fabrication, high to low-density

Pyroxenes ((Ca, Mg, Fe, Mn) 2 Si 2 O 6 ) belong to the most abundant rockforming minerals that make up the surface of rocky planets and moons. Therefore sputtering of pyroxenes by solar wind ions has to be considered as a very important process for modifying the surface of planetary bodies. In order to quantify this effect, sputtering of wollastonite (CaSiO 3 ) by He 2+ ions, which are seen as a very prominent contribution to solar wind potential sputtering, was investigated. Thin films of CaSiO 3 deposited on a quartz crystal microbalance were irradiated allowing precise in-situ real time sputtering yield measurements. Experimental results were compared with simulations with the code SDTrimSP, which were improved by adapting the used surface binding energy.On a freshly prepared surface He 2+ ions show a significant increase in sputtering compared to equally fast He + ions. The yield, however, decreases exponentially with fluence, reaching steady state at considerably lower values after sputtering of the first few monolayers.Experiments using Ar 8+ ions show a similar behavior and are qualitatively explained by a preferential depletion of surface oxygen due to potential sputtering. A corresponding quantitative model is applied, which is able to reproduce the observed potential sputtering behavior of both He and Ar very well. The results of these calculations support the assumption that mainly O atoms are affected by potential sputtering. We conclude that the defect-mediated model of potential sputtering is also well-suited for CaSiO 3 .

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We study the filling of single‐walled carbon nanotubes (SW‐ CNTs) with ferrocene molecules. Using e‐DIPS SWCNTs with a mean diameter of 1.7 nm, we obtain a filling factor as high as 90%. At elevated temperatures in high vacuum the filled SWCNTs are transformed to double‐walled carbon nanotubes (DWCNTs). Temperature dependence of inner tube growth is investigated by Raman spectroscopy. The electronic properties of the obtained nanostructures are studied by X‐ray photoelectron spectroscopy and near edge X‐ray absorption fine structure spectroscopy. It is found that the growth temperature is higher for larger diameter inner tubes. It is demonstrated that ferrocene filling leads to electron doping of SWCNTs.

The sputtering of wollastonite (CaSiO3) by solar wind-relevant ions has been investigated experimentally and the results are compared to the binary collision approximation (BCA) codes SDTrimSP and SRIM-2013. Absolute sputtering yields are presented for Ar projectiles as a function of ion impact energy, charge state and impact angle as well as for solar wind H projectiles as a function of impact angle. Erosion of wollastonite by singly charged Ar ions is dominated by kinetic sputtering. The absolute magnitude of the sputtering yield and its dependence on the projectile impact angle can be well described by SDTrimSP as long as the actual sample composition is used in the simulation. SRIM-2013 largely overestimates the yield especially at glancing impact angles. For higher Ar charge states, the measured yield is strongly enhanced due to potential sputtering. Sputtering yields under solar wind-relevant H + bombardment are smaller by two orders of magnitude compared to Ar. Our experimental yields also show a less pronounced angular dependence than predicted by both BCA programs, probably due to H implantation in the sample. Based on our experimental findings and extrapolations to other solar wind ions by using SDTrimSP we present a model for the complete solar wind sputtering of a flat wollastonite surface as a function of projectile ion impact angle, which predicts a sputtering yield of 1.29 atomic mass units per solar wind ion for normal impact. We find that mostly He and some heavier ions increase the sputtering yield by more than a factor of two as compared to H + bombardment only.

Carbon nanotubes are a natural choice as gas sensor components given their high surface to volume ratio, electronic properties, and capability to mediate chemical reactions. However, a realistic assessment of the interaction of the tube wall and the adsorption processes during gas phase reactions has always been elusive. Making use of ultraclean single-walled carbon nanotubes, we have followed the adsorption kinetics of NO2 and found a physisorption mechanism. Additionally, the adsorption reaction directly depends on the metallic character of the samples. Franck–Condon satellites, hitherto undetected in nanotube–NOx systems, were resolved in the N 1s X-ray absorption signal, revealing a weak chemisorption, which is intrinsically related to NO dimer molecules. This has allowed us to identify that an additional signal observed in the higher binding energy region of the core level C 1s photoemission signal is due to the C=O species of ketene groups formed as reaction byproducts . This has been supported by density functional theory calculations. These results pave the way toward the optimization of nanotube-based sensors with tailored sensitivity and selectivity to different species at room temperature.