Spectra of two-step gamma cascades following the thermal 162Dy(n,gamma)163Dy reaction have been measured. Distinct peaklike structures observed at the midpoints of these spectra are interpreted as a manifestation of the low-energy isovector M1 vibrational mode of excited 163Dy nuclei.

Precisely engineered changes in Fermi levels of graphene-based materials are of high importance for their applications in electronic and electrochemical devices. Such applications include photoelectrochemical reactions or enhanced electrochemical performance toward reduction of oxygen. Here we describe a method for scalable and tunable boron doping of graphene via thermal exfoliation of graphite oxide in BF 3 atmosphere at different temperatures. The temperature and atmospheric composition during exfoliation influences the kinetics of decomposition of the reactants and levels of doping, which range from 23 to 590 ppm. The resulting materials were characterized by prompt γ-ray analysis, X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron microscopy. Recent claims on enhanced catalytic properties of boron-doped graphenes toward the reduction of oxygen were addressed, as well as similar claims on enhanced capacitance.

The fabrication of graphenes doped with electron withdrawing/donating elements can be realized through the synthesis procedures reported in this paper. Doping of the graphenes occurs during the thermal exfoliation step of graphite oxide in the presence of the dopant containing gas (BF 3 or NH 3 ).The materials are extensively characterized by high-resolution X-ray photoelectron spectroscopy, prompt gamma-ray activation analysis and Raman spectroscopy. Their electrical and electrochemical properties related to heterogeneous electron transfer rates and oxygen reductions are investigated. The doped materials display significant differences in their electronic properties where graphenes doped by electron donating dopants exhibit the largest conductivity as compared to those doped by electron accepting dopants. The scalable method reported here is able to successfully implant B and N into the graphene lattice and hence presented important future implications for the production of these materials on an industrial scale. ApparatusA JEOL 7600F eld-emission scanning electron microscope (JEOL, Japan) was used to acquire images under normal SEM mode and gentle-beam mode (GB). The samples were prepared

In the EXILL campaign a highly efficient array of high purity germanium (HPGe) detectors was operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of γ-rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 108 n s−1cm−2 at the target position and negligible neutron halo. The target was surrounded by an array of eight to ten anti-Compton shielded EXOGAM Clover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr3:(Ce) detectors from the FATIMA collaboration. The detectors were arranged in an array of rhombicuboctahedron geometry, providing the possibility to carry out very precise angular correlation and directional-polarization correlation measurements. The triggerless acquisition system allowed a signal collection rate of up to 6 × 105 Hz. The data allowed to set multi-fold coincidences to obtain decay schemes and in combination with the FATIMA array of LaBr3:(Ce) detectors to analyze half-lives of excited levels in the pico- to microsecond range. Precise energy and efficiency calibrations of EXILL were performed using standard calibration sources of 133Ba, 60Co and 152Eu as well as data from the reactions 27Al(n,γ)28Al and 35Cl(n,γ)36Cl in the energy range from 30 keV up to 10 MeV.

Chemical synthesis of graphene relies on the usage of various chemical reagents. The initial synthesis step, in which graphite is oxidized to graphite oxide, is achieved by a combination of chemical oxidants and acids. A subsequent chemical reduction step eliminates/reduces most oxygen functionalities to yield graphene. We demonstrate here that these chemical treatments significantly contaminate graphene with heteroatoms/metals, depending on the procedures followed. Contaminations with heteroatoms (N, B, Cl, S) or metals (Mn, Al) were present at relatively high concentrations (up to 3 at%), with their chemical states dependent on the procedures. Such unintentional contaminations (unwanted doping) during chemical synthesis are rarely anticipated and reported, although the heteroatoms/metals may alter the electronic and catalytic properties of graphene. In fact, the levels of unintentionally introduced contaminants on graphene are often higher than typical levels found on intentionally doped graphene. Our findings are important for scientists applying chemical methods to prepare graphene.