The configuration of La ions of La(2)@C(80) in the [80]fullerene cage was investigated by use of quantum chemical calculations. We found that the D(3)(d)() configuration is the global minimum in total energy, being more stable by 1.9 kcal/mol than the D(2)(h)() configuration, which has been considered to be the most stable. The potential energy surface calculation clarified that La ions travel between 10 equivalent D(3)(d)() positions through D(2)(h)() positions and consequently form pentagonal dodecahedral trajectory, which is in good agreement with the previous synchrotron radiation structural study. The experimental and theoretical investigation of the Raman spectrum revealed that the symmetry of molecular vibration is dramatically reduced simply by encapsulation of two La ions, and resulting vibrational modes were successfully assigned. The Raman peak at 163 cm(-)(1) was interpreted as the in-phase synchronously coupled mode of the [80]fullerene cage elongation and the La-La stretching, rather than a conventional and naive assignment as a metal-to-cage vibration mode.
The Engineering Materials Diffractometer “TAKUMI” is designed and has been constructed at Materials & Life Science Facility (MLF) of Japan Proton Accelerator Research Complex (J-PARC) to conduct various kinds of studies on materials science and engineering and to promote industrial applications, related with strain measurements. The commissioning of TAKUMI has been started from September 2008, and several user programs have been done. In the commissioning, a resolution Δd/d at high resolution mode (with incident beam collimation) of less than 0.2% was achieved in a diffraction experiment using 2 mm diameter thick annealed piano wire. The d-range measured by TAKUMI with single pulse frame, i.e. standard operation, was confirmed to be 0.05 nm to 0.27 nm, showing that the optimum range for materials research is covered by this machine. TAKUMI adopted an event mode data recording method. It was found that the recording method is very useful to manipulate data as we like, for instance, detector range, time of flight binning width and time resolved data, even after the experiment has been finished.
The small and wide angle neutron scattering instrument (TAIKAN) is designed to cover the wide q range of 0.005 < q < 15 Å-1 by using neutrons in the wide wavelength range of 0.5 < < 7.8 Å and four detector banks of small-, middle-, high-angle, and backward detector banks. The q resolution of TAIKAN was theoretically estimated to be about 5 % at q = 0.1 Å-1 with the small-angle detector bank and less than 2 % in the q range of q > 0.3 Å-1 with the other banks. The q resolution was compared with the values experimentally obtained from the widths of Bragg peaks of a standard sample, silver behenate. The results of the experiment were consistent with the theory. It was confirmed that TAIKAN was completed as was expected.
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