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to play a crucial role as essential building blocks in future high-tech devices. [1][2][3][4][5][6][7][8] Already in the late 1960s, early studies on the structural and electronic properties of bulk TMDs had started and are detailed in a report by Wilson and Yoffe. [9] TMDs are layered materials which combine a transition metal (M: Mo, W, Ti, Zr, etc.) and a chalcogen (X: S, Se, or Te) in the general formula MX 2 with one layer of M atoms sandwiched between two layers of X atoms. [10] Group VIB TMDs with a 2H structural phase (e.g., MoSe 2 ) are the most explored representatives of such systems. They are characterized by an intrinsic bandgap within the visible and near-infrared regions. [11] Furthermore, the material system exhibits a transition from an indirect to a direct bandgap located at the K or K′ points of the hexagonal Brillouin zone, linked to a decrease in the number of layers from the bulk crystal to a monolayer. [12,13] Moreover, such materials also possess a strong spin-orbit interaction due to the presence of a relatively heavy transition metal along with huge exciton binding energies [14][15][16] resulting from a strong Coulomb interaction and a lack of dielectric screening. These properties lead to a valence-band splitting that strongly affects Alloying semiconductors is often used to tune the material properties desired for device applications. The price for this tunability is the extra disorder caused by alloying. In order to reveal the features of the disorder potential in alloys of atomically thin transition-metal dichalcogenides (TMDs) such as Mo x W 1−x Se 2 , the exciton photoluminescence is measured in a broad temperature range between 10 and 200 K. In contrast to the binary materials MoSe 2 and WSe 2 , the ternary system demonstrates non-monotonous temperature dependences of the luminescence Stokes shift and of the luminescence linewidth. Such behavior is a strong indication of a disorder potential that creates localized states for excitons and affects the exciton dynamics responsible for the observed non-monotonous temperature dependences. A comparison between the experimental data and the results obtained by Monte Carlo computer simulations provides information on the energy scale of the disorder potential and also on the shape of the density of localized states created by disorder. Statistical spatial fluctuations in the distribution of the chemically different material constituents are revealed to cause the disorder potential responsible for the observed effects. A deeper understanding of the disorderinduced effects is vital for prospective TMD alloy-based devices.

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Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), laser Raman spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurements. It was observed that as-received fly ash was capable of producing CNFs in high yield by CCVD, starting at a relatively low temperature of 400°C. Laser Raman spectra and TGA thermograms showed that the carbonaceous products which formed were mostly disordered. Small bundles of CNTs and CNFs observed by TEM and energy-dispersive spectroscopy (EDS) showed that the catalyst most likely responsible for CNF formation was iron in the form of cementite; X-ray diffraction (XRD) and Mössbauer spectroscopy confirmed these findings.