ABSTRACT
A suitable way to modify the electronic properties of graphene-while maintaining the exceptional properties associated with its two-dimensional (2D) nature-is its functionalisation. In particular, the incorporation of hydrogen isotopes in graphene is expected to modify its electronic properties leading to an energy gap opening, thereby rendering graphene promising for a widespread of applications. Hence, deuterium (D) adsorption on free-standing graphene was obtained by high-energy electron ionisation of D2 and ion irradiation of a nanoporous graphene (NPG) sample. This method allows one to reach nearly 50 at.% D upload in graphene, higher than that obtained by other deposition methods so far, towards low-defect and free-standing D-graphane. That evidence was deduced by X-ray photoelectron spectroscopy of the C 1s core level, showing clear evidence of the D-C sp3 bond, and Raman spectroscopy, pointing to remarkably clean and low-defect production of graphane. Moreover, ultraviolet photoelectron spectroscopy showed the opening of an energy gap in the valence band. Therefore, high-energy electron ionisation and ion irradiation is an outstanding method for obtaining low defect D-NPG with a high D upload, which is very promising for the fabrication of semiconducting graphane on large scale.
ABSTRACT
Serious radiation damage due to the high energy neutron/gamma fluxes is expected for optical materials such as scintillators, windows, and lenses which will be part of the plasma diagnostics in future fusion devices. Radiation induced absorption represents a major concern for these components for which experimental validation under as near as possible reactor conditions becomes essential. A new experimental system has been developed at the CIEMAT Nayade 60Co gamma irradiation facility for in situ radiation induced optical absorption measurements, covering a spectral range between 370 and 730 nm. This setup consists in a rotating sample holder which allows one to collect incident light (reference signal) and transmitted light through the material to be tested as a function of irradiation dose. This is an advanced and robust system which overcomes the important experimental difficulties that radiation involves providing a valuable testing capability for transmission components and scintillators under realistic fusion conditions. A detailed description of the experimental arrangement, together with preliminary tests carried out for system validation is given in this paper.
