NASDA Space Program In Japan

The National Space Development Agency of Japan, NASDA, was established on October 1, 1969, under the NASDA Law as the nucleus of the nation\u27s space development effort in order to promote space development and utilization for peaceful purposes. NASDA, in a sense, is the equibalent of NASA in the United States, or ESA ( European Space Agency ) in Europe. In accordance with the basic program for space development decided by the Prime Minister, NASDA is undertaking (1) the development, launching and tracking of satellites and satellite launch vehicles and (2) the development and consolidation of software, equipment and facilities needed for launching and tracking. So far, NASDA has succeeded in launching four satellites by means of its N Launch vehicle from the Tanegashima Space Center, three of them into 1,000 km circular orbit and one into geosynchronous orbit. NASDA succeeded also in the insertion of three satellites into geosynchronous orbits at their projected positions after having been launched by US NASA\u27s Delta 2914 from ETR under the reimbursable launch contract. NASDA activities in general will be overviewed in this report

Optimizing picene molecular assembling by supersonic molecular beam deposition

Here we report an investigation of the growth of picene by supersonic molecular beam deposition on thermal silicon oxide and on a self-assembled monolayer of hexamethyldisiloxane (HMDS). In both cases film morphology shows a structure with very sharp island edges and well-separated islands which size and height depend on the deposition conditions. Picene films growth on bare silicon covered with hydrophobic HDMS shows islands characterized by large regular crystallites of several micrometers; on the other hand, films growth on silicon oxide shows smaller and thicker islands. We analyzed the details of the growth model and describe it as a balancing mechanism involving the weak interaction between molecules and surface and the strong picene-picene interaction that leads to a different Schwoebel-Ehrlich barrier in the first layer with respect to the successive one. Finally, we study the charge transport properties of these films by fabricating field-effect transistors devices in both top and bottom contact configuration. We notice that substrate influences the electrical properties of the device and we obtained a maximum mobility value of 1.2 cm2 V-1 s-1 measured on top contact devices in air. © 2012 American Chemical Society

Fabrication of C₆₀ field-effect transistors with polyimide and Ba_0.4Sr_0.6Ti_0.96O₃ gate insulators

Flexible C60 field-effect transistor (FET) device has been fabricated with polyimide gate insulator on the poly(ethylene terephthalate) substrate, and n-channel normally-off FET properties are observed in this FET device. The field-effect mobility, ?, is estimated to be ~10-2 cm2 V-1 s-1 at 300 K. Furthermore, the C60 FET has been fabricated with high dielectric Ba0.4Sr0.6Ti0.96O3 (BST) gate insulator, showing n-channel properties; the ? value is estimated to be ~10-4 cm2 V-1 s-1 at 300 K. The FET device operates at very low gate voltage, VG, and low drain-source voltage, VDS. Thus these C60 FET devices possess flexibility and low-voltage operation characteristic of polyimide and BST gate insulators, respectively.</p

Fabrication of field-effect transistor device with higher fullerene, C₈₈

A fullerene field-effect transistor (FET) device has been fabricated with thin films of C88, and n-channel normally-on depletion-type FET properties have been found in this FET device. The C88 FET exhibited a high mobility, &#956;, of 2.5 x 10-3 cm2 V-1 s-1 at 300 K, in fullerene FETs. The carrier transport showed a thermally-activated hopping transport. The n-channel normally-on FET properties and the hopping transport reflect the small mobility gap and low carrier concentration in the channel region of C88 thin-films.</p

Superconductivity in a new layered triangular-lattice system Li2IrSi2

We report on the crystal structure and superconducting properties of a novel iridium-silicide, namely Li2IrSi2. It has a Ag2NiO2-type structure (space group R-3m) with the lattice parameters a = 4.028 30(6) Å and c = 13.161 80(15) Å. The crystal structure comprises IrSi2 and double Li layers stacked alternately along the c-axis. The IrSi2 layer includes a two-dimensional Ir equilateral-triangular lattice. Electrical resistivity and static magnetic measurements revealed that Li2IrSi2 is a type-II superconductor with critical temperature (Tc) of 3.3 K. We estimated the following superconducting parameters: lower critical field Hc1(0) ~ 42 Oe, upper critical field Hc2(0) ~ 1.7 kOe, penetration depth λ0 ~ 265 nm, coherence length ξ0 ~ 44 nm, and Ginzburg–Landau parameter κGL ~ 6.02. The specific-heat data suggested that superconductivity in Li2IrSi2 could be attributed to weak-coupling Cooper pairs

Role of dynamic Jahn-Teller distortions in Na2C60 and Na2CsC60 studied by NMR

Through 13C NMR spin lattice relaxation (T1) measurements in cubic Na2C60, we detect a gap in its electronic excitations, similar to that observed in tetragonal A4C60. This establishes that Jahn-Teller distortions (JTD) and strong electronic correlations must be considered to understand the behaviour of even electron systems, regardless of the structure. Furthermore, in metallic Na2CsC60, a similar contribution to T1 is also detected for 13C and 133Cs NMR, implying the occurence of excitations typical of JT distorted C60^{2-} (or equivalently C60^{4-}). This supports the idea that dynamic JTD can induce attractive electronic interactions in odd electron systems.Comment: 3 figure

Evidence for phase formation in potassium intercalated 1,2;8,9-dibenzopentacene

We have prepared potassium intercalated 1,2;8,9-dibenzopentacene films under vacuum conditions. The evolution of the electronic excitation spectra upon potassium addition as measured using electron energy-loss spectroscopy clearly indicate the formation of particular doped phases with compositions K$_x$dibenzopentacene ($x$ = 1,2,3). Moreover, the stability of these phases as a function of temperature has been explored. Finally, the electronic excitation spectra also give insight into the electronic ground state of the potassium doped 1,2;8,9-dibenzopentacene films.Comment: 6 pages, 5 figures. arXiv admin note: text overlap with arXiv:1201.200

Multipurpose High Frequency Electron Spin Resonance Spectrometer for Condensed Matter Research

We describe a quasi-optical multifrequency ESR spectrometer operating in the 75-225 GHz range and optimized at 210 GHz for general use in condensed matter physics, chemistry and biology. The quasi-optical bridge detects the change of mm wave polarization at the ESR. A controllable reference arm maintains a mm wave bias at the detector. The attained sensitivity of 2x10^10 spin/G/(Hz)1/2, measured on a dilute Mn:MgO sample in a non-resonant probe head at 222.4 GHz and 300 K, is comparable to commercial high sensitive X band spectrometers. The spectrometer has a Fabry-Perot resonator based probe head to measure aqueous solutions, and a probe head to measure magnetic field angular dependence of single crystals. The spectrometer is robust and easy to use and may be operated by undergraduate students. Its performance is demonstrated by examples from various fields of condensed matter physics.Comment: submitted to Journal of Magnetic Resonanc

Electronic structure of pristine and K-doped solid picene: Non-rigid-band change and its implication for electron-intramolecular-vibration interaction

We use photoemission spectroscopy to study electronic structures of pristine and K-doped solid picene. The valence band spectrum of pristine picene consists of three main features with no state at the Fermi level (EF), while that of K-doped picene has three structures similar to those of pristine picene with new states near EF, consistent with the semiconductor-metal transition. The K-induced change cannot be explained with a simple rigid-band model of pristine picene, but can be interpreted by molecular orbital calculations considering electron-intramolecular-vibration interaction. Excellent agreement of the K-doped spectrum with the calculations points to importance of electron-intramolecular-vibration interaction in K-doped picene.Comment: This article is accepted by Physical Review