Coherent transfer of light polarization to electron spins in a semiconductor

We demonstrate that the superposition of light polarization states is coherently transferred to electron spins in a semiconductor quantum well. By using time-resolved Kerr rotation we observe the initial phase of Larmor precession of electron spins whose coherence is transferred from light. To break the electron-hole spin entanglement, we utilized the big discrepancy between the transverse g-factors of electrons and light holes. The result encourages us to make a quantum media converter between flying photon qubits and stationary electron spin qubits in semiconductors.Comment: 4 pages. Submitted to Physical Review Letter

Electron-energy-loss function of LiTaO3 and LiNbO3 by x-ray photoemission spectroscopy: Theory and experiment

We report experimental energy-loss structures in x-ray photoemission spectra of single crystalline LiTaO3 and LiNbO3, and then compare these with theoretical electron-energy-loss functions calculated from first principles using the full-potential linearized augmented plane-wave method in the local-density approximation. The energy-loss structure of core electrons can be approximated by a sum of four components: for LiTaO3, the peaks positioned at 8.0, 13.4, 15.8, and 22.6 eV; for LiNbO3, those positioned at 7.0, 12.0, 14.5, and 21.8 eV. The momentum matrix elements between Bloch functions were evaluated to determine the electron energy-loss functions. The theoretical electron-energy-loss functions agreed fairly well with the experimental one. The experimental peaks positioned at 8.0, 13.4, and 15.8 eV for LiTaO3 and those at 7.0, 12.0, and 14.5 eV for LiNbO3 were assigned to the interband transitions from the valence band to the conduction bands. The peaks at 22.6 eV for LiTaO3 and 21.8 eV for LiNbO3 were ascribed to the electron excitation from the O 2s level to the lower conduction band

Photoelectron energy-loss functions of SrTiO3, BaTiO3, and TiO2: Theory and experiment

We compare experimental O 1s electron energy-loss structures below 30 eV of single crystalline SrTiO3 ,BaTiO3, and TiO2 with their theoretical electron energy-loss functions. The photoelectron energy-loss structuresof in situ fractured surface in ultrahigh vacuum can be approximated by a sum of four components forSrTiO3 and BaTiO3, and of three components for TiO2. Electronic structures were calculated from first principlesusing the full-potential linearized augmented plane-wave method in the local-density approximation. Themomentum matrix elements between Bloch functions were evaluated to determine the electron energy-lossfunctions. The theoretical electron energy-loss functions agree well with experimental spectra except a structureat around 20 eV of SrTiO3 and that at around 18 eV of BaTiO3. The difference of high binding energypeaks is explained from the positions of semicore states

Large-scale CO (J=4-3) Mapping toward the Orion-A Giant Molecular Cloud

We have mapped the Orion-A Giant Molecular Cloud in the CO (J=4-3) line with the Tsukuba 30-cm submillimeter telescope.The map covered a 7.125 deg^2 area with a 9' resolution, including main components of the cloud such as Orion Nebula, OMC-2/3, and L1641-N. The most intense emission was detected toward the Orion KL region. The integrated intensity ratio between CO (J=4-3) and CO (J=1-0) was derived using data from the Columbia-Univ. de Chile CO survey, which was carried out with a comparable angular resolution. The ratio was r_{4-3/1-0} ~ 0.2 in the southern region of the cloud and 0.4-0.8 at star forming regions. We found a trend that the ratio shows higher value at edges of the cloud. In particular the ratio at the north-eastern edge of the cloud at (l, b) = (208.375 deg, -19.0 deg) shows the specific highest value of 1.1. The physical condition of the molecular gas in the cloud was estimated by non-LTE calculation. The result indicates that the kinetic temperature has a gradient from north (Tkin=80 K) to south (20 K). The estimation shows that the gas associated with the edge of the cloud is warm (Tkin~60 K), dense (n_{H_2}~10^4 cm^{-3}), and optically thin, which may be explained by heating and sweeping of interstellar materials from OB clusters.Comment: 12 pages, 11 figures; Accepted for publication in PAS

Electronic structure and electrical properties of amorphous OsO2

The valence-band spectrum of an amorphous OsO2 film deposited by glow discharge of OsO4 vapor can be predicted well with calculated electronic band structure of crystalline OsO2 from first principles using the liner-muffin-tin-orbital method with the local-density approximation. Resistivity of the amorphous OsO2 was less than 631023 V cm at 80 K, and it was almost temperature independent, but the temperature coefficient of resistivity was negative. The Hall coefficient of the amorphous OsO2 increased with temperature, and was saturated at around 220 K. Temperature dependence of the Hall mobility was proportional to T3/2, and it implies that the scattering of charged carriers by ionized atoms is dominant below 220 K

CO oxidation on perovskite-type LaCoO3 synthesized using ethylene glycol and citric acid

In order to synthesize perovskite-type LaCoO3 with good surface crystallinity, the gel prepared by adding both ethylene glycol (EG) and citric acid (CA) to the aqueous solution of La(NO3)3 center dot 6H(2)O and Co(NO3)(2) center dot 6H(2)O was fired at 600 degrees C in air for 3 h. The transmission electron microscopy (TEM) observation indicated that the particles of LaCoO3 tended to have a uniform shape at EG/CA = 4. Although, the specific surface area of LaCoO3 synthesized using both EG and CA was slightly smaller than that of LaCoO3 synthesized using only CA, the catalytic activity of CO oxidation became higher by adding EG