Photoemission Angular Distribution Beyond the Single Wavevector Description of Photoelectron Final States

We develop a novel simulation procedure for angle-resolved photoemission spectroscopy (ARPES), where a photoelectron wave function is set to be an outgoing plane wave in a vacuum associated with the emitted photoelectron wave packet. ARPES measurements on the transition metal dichalcogenide $1T$-$\mathrm{Ti}\mathrm{S}_2$ are performed, and our simulations exhibit good agreement with experiments. Analysis of our calculated final state wave functions quantitatively visualizes that they include various waves due to the boundary condition and the uneven crystal potential. These results show that a more detailed investigation of the photoelectron final states is necessary to fully explain the photon-energy- and light-polarization-dependent ARPES spectra.Comment: 6+14 pages, 4+15 figure

Observations of exciton and carrier spin relaxation in Be doped p-type GaAs

<span lang="EN-US" new="" style="font-family: ;" times=""><font color="#000000">We have investigated the exciton and carrier spin relaxation in Be-doped p-type GaAs. Time-resolved spin-dependent photoluminescence (PL) measurements revealed spin relaxation behaviors between 10 and 100K. Two PL peaks were observed at 1.511 eV (peak 1) and 1.497 eV (peak 2) at 10K, and are attributed to the recombination of excitons bound to neutral Be acceptors (peak 1) and the band-to-acceptor transition (peak 2). The spin relaxation times of both PL peaks were measured to be 1.3-3.1 ns at 10-100K, and found to originate from common electron spin relaxation. The observed existence of a carrier density dependence of the spin relaxation time at 10-77K indicates that the Bir-Aronov-Pikus process is the dominant spin relaxation mechanism. (C) 2014 AIP Publishing LLC.</font></span

Self-propagating calciferous particles detected in a human cell line Kasumi-6

Tiny particles were found in the medium in the presence of the human leukemia cell line Kasumi-6. The particles were separated from human cells by filtration and incubated in RPMI1640 supplemented with 10% fetal calf serum at 37 C. The particles increased in number very slowly in the liquid medium but did not reveal any biological activity. Transmission electron microscopy of the particles showed a spheroid or ovoid shape in ultrathin section. No specific polypeptides from the purified particles were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), except for bovine fetuin that adsorbed to the surface of the particles. X-ray diffractometry as well as Fourier transform infrared spectrometry suggested the particles consisted of hydroxyapatite. The mechanism of self-propagation of the hydroxyapatite particles in liquid medium is currently unknown. This type of particle has been overlooked for a long period because it is noncultivable. It will be necessary to examine its biological effects to the cultured cells