The Greenhouse Gases Observing Satellite (GOSAT) monitors carbon dioxide (CO(2)) and methane (CH(4)) globally from space using two instruments. The Thermal and Near Infrared Sensor for Carbon Observation Fourier-Transform Spectrometer (TANSO-FTS) detects gas absorption spectra of the solar short wave infrared (SWIR) reflected on the Earth's surface as well as of the thermal infrared radiated from the ground and the atmosphere. TANSO-FTS is capable of detecting three narrow bands (0.76, 1.6, and 2.0 microm) and a wide band (5.5-14.3 microm) with 0.2 cm(-1) spectral resolution (interval). The TANSO Cloud and Aerosol Imager (TANSO-CAI) is an ultraviolet (UV), visible, near infrared, and SWIR radiometer designed to detect cloud and aerosol interference and to provide the data for their correction. GOSAT is placed in a sun-synchronous orbit 666 km at 13:00 local time, with an inclination angle of 98 degrees . A brief overview of the GOSAT project, scientific requirements, instrument designs, hardware performance, on-orbit operation, and data processing is provided.

We investigated the elastic properties of the iron-based superconductor Ba(Fe 1Àx Co x ) 2 As 2 with eight Co concentrations. The elastic constant C 66 shows a large elastic softening associated with structural phase transition. C 66 was analyzed on the basis of the localized and itinerant pictures of Fe-3d electrons, which shows a strong electronlattice coupling and a possible mass enhancement in this system. The results are similar to those of unconventional superconductors, where the properties of the system are governed by quantum fluctuations associated with the zerotemperature critical point of long-range order, namely, the quantum critical point (QCP). In this system, the inverse of C 66 behaves just like the magnetic susceptibility in magnetic QCP systems. Although the QCPs of these existing superconductors are all ascribed to antiferromagnetism, our systematic studies on the canonical iron-based superconductor Ba(Fe 1Àx Co x ) 2 As 2 have revealed that there is a signature of ''structural quantum criticality'' in this material, which thus far has had no precedent. The elastic constant anomaly is suggested to concern with the emergence of superconductivity. These results highlight the strong electron-lattice coupling and effect of the band in this system, thus challenging the prevailing scenarios that focus on the role of iron 3d orbitals.

An ordered phase showing remarkable electronic anisotropy in proximity to the superconducting phase is now a hot issue in the field of high-transition-temperature superconductivity. As in the case of copper oxides, superconductivity in iron arsenides competes or coexists with such an ordered phase. Undoped and underdoped iron arsenides have a magnetostructural ordered phase exhibiting stripe-like antiferromagnetic spin order accompanied by an orthorhombic lattice distortion; both the spin order and lattice distortion break the tetragonal symmetry of crystals of these compounds. In this ordered state, anisotropy of in-plane electrical resistivity is anomalous and difficult to attribute simply to the spin order and/or the lattice distortion. Here, we present the anisotropic optical spectra measured on detwinned BaFe 2 As 2 crystals with light polarization parallel to the Fe planes. Pronounced anisotropy is observed in the spectra, persisting up to an unexpectedly high photon energy of about 2 eV. Such anisotropy arises from an anisotropic energy gap opening below and slightly above the onset of the order. Detailed analysis of the optical spectra reveals an unprecedented electronic state in the ordered phase.anisotropic electronic state | iron pnictide | optical spectrum H igh-transition-temperature (high-T c ) superconductivity realized in both copper oxides and iron arsenides shares common features, namely, the superconducting phase is in close proximity to a symmetry-breaking phase and these phases coexist under certain circumstances, but apparently compete with each other. The close proximity suggests that our understanding of high-T c superconductivity will greatly improve once the nature of this proximate phase is revealed. The parent compounds of iron-arsenide superconductors, with BaFe 2 As 2 as a representative example, are unique metals that undergo a tetragonal-toorthorhombic structural phase transition at temperature T s with a shorter b axis and a longer a axis in the orthorhombic phase always accompanied by antiferromagnetic (AF) spin order at temperature T N . T N is equal to T s in some compounds (1-3) and slightly lower than T s in others (4). BaFe 2 As 2 exhibits stripe-like AF order in which Fe spins align antiferromagnetically in the a-axis direction in the Fe plane and ferromagnetically in the b-axis direction. Anisotropic electronic properties have been experimentally examined by various methods, such as neutron scattering (5), scanning tunneling microscopy (STM) (6), and angleresolved photoemission spectroscopy (ARPES) (7,8). These experiments suggest strong anisotropy of spin excitation and of the shape of Fermi surfaces. However, most of the experiments were performed on twinned crystals with randomly oriented domains, which inhibit the observation of genuine anisotropy.Recently, anisotropic resistivity has been measured on detwinned crystals (9, 10). The anisotropy of resistivity is quite anomalous in that the resistivity along the spin-ferromagnetic (FM) direction with a shorter b axis is...

We investigated the optical spectrum of Ba(Fe1−xCox)2As2 single crystals with various doping levels. It is found that the low-energy optical conductivity spectrum of this system can be decomposed into two components: a sharp Drude term and a broad "incoherent" term. For the compounds showing magnetic order, a gap appears predominantly in the "incoherent" component, while an swave like superconducting gap opens in both components for highly doped compounds. The Drude weight steadily increases as doping proceeds, consistent with electron doping in this system. On the other hand, the "incoherent" spectral weight is almost doping independent, but its spectral feature is intimately connected with the magnetism. We demonstrate that the presence of two distinct components in the optical spectrum well explains the doping and temperature dependences of the dc resistivity.

We investigated the in-plane resistivity anisotropy for underdoped Ba(Fe(1-x)Co(x))(2)As(2) single crystals with improved quality. We demonstrate that the anisotropy in resistivity in the magnetostructural ordered phase arises from the anisotropy in the residual component which increases in proportion to the Co concentration x. This gives evidence that the anisotropy originates from the impurity scattering by Co atoms substituted for the Fe sites, rather than the so far proposed mechanisms such as the anisotropy of Fermi velocities of reconstructed Fermi surface pockets. As doping proceeds to the paramagnetic-tetragonal phase, a Co impurity transforms to a weak and isotropic scattering center.

We show that the Fermi surface (FS) in the antiferromagnetic phase of BaFe(2)As(2) is composed of one hole and two electron pockets, all of which are three dimensional and closed, in sharp contrast to the FS observed by angle-resolved photoemission spectroscopy. Considerations on the carrier compensation and Sommerfeld coefficient rule out existence of unobserved FS pockets of significant sizes. A standard band structure calculation reasonably accounts for the observed FS, despite the overestimated ordered moment. The mass enhancement, the ratio of the effective mass to the band mass, is 2-3.

Centimeter sized platelet single crystals of KFe2As2 were grown using a self-flux method. An encapsulation technique using commercial stainless steel container allowed the stable crystal growth lasting for more than 2 weeks. Ternary K-Fe-As systems with various starting compositions were examined to determine the optimal growth conditions. Employment of KAs flux led to the growth of large single crystals with the typical size of as large as 15 mm × 10 mm × 0.4 mm. The grown crystals exhibit sharp superconducting transition at 3.4 K with the transition width 0.2 K, as well as the very large residual resistivity ratio exceeding 450, evidencing the good sample quality.

We investigated the transport properties of BaFe 2 As 2 single crystals before and after annealing with BaAs powder. The annealing remarkably improves transport properties, in particular, the magnitude of residual resistivity, which decreases by a factor of more than 10. From the resistivity measurement on detwinned crystals, we found that the anisotropy of the in-plane resistivity is remarkably diminished after annealing, indicative of dominant contributions to the charge transport from the carriers with isotropic and high mobility below magnetostructural transition temperature T s and the absence of nematic state above T s . We found that the Hall resistivity shows strong nonlinearity against magnetic field, and the magnetoresistance becomes very large at low temperatures. These results give evidence for the manifestation of multiple carriers with distinct characters in the ordered phase below T s . By analyzing the magnetic-field dependences, we found that at least three carriers equally contribute to the charge transport in the ordered phase, which is in good agreement with the results of recent quantum oscillation measurements.