Total energy calculation of high pressure selenium: The origin of incommensurate modulations in Se-IV and the instability of proposed Se-II

We present calculation of the high pressure crystal structures in selenium, including rational approximants to the recently reported incommensurate phases. We show how the incommensurate phases can be intuitively explained in terms of imaginary phonon frequencies arising from Kohn anomalies in the putative undistorted phase. We also find inconsistencies between the calculated and experimental Se-II phase - the calculations show it to be a metastable metal while the experiment finds a stable semiconductor. We propose that the experimentally reported structure is probably in error.Comment: 4 pages 4 figure

Critical Point Dewetting : the role of the gravity and the long-range force

この論文は国立情報学研究所の電子図書館事業により電子化されました。研究会報告通常、2液相分離系においては、臨界点近くで片方の液相が固体基板を覆ういわゆる臨界点濡れ現象(critical point wetting)が観測される。ところが、液体-基板間の強い長距離相互作用と重力ポテンシャルとが競合している場合、全く逆の"critical point dewetting"とも呼ぶべき現象が起こりうる。我々は、液体Se-Tl系と石英基板の間の濡れの振る舞いを調べ、その結果、この"critical point dewetting"現象を観測した

EICO measurements of inner-core excited mixed rare-gas clusters

The spectra of deep inner-core excited mixed rare-gas clusters were recorded by using electron ion coincidence (EICO) and multi-hit momentum imaging (MHMI) techniques. The EICO spectra for Ar99Kr1 clusters reveal that singly charged ions are emitted from the inner-core excited clusters in addition to the multiple charged ions. The dependence of the EICO spectra on photon energy and cluster size suggests that the holes created through vacancy cascade on the krypton atoms are transferred to the surrounding atoms, and that the singly charged ions are the primary product of the krypton photoabsorption. Charge localization is suggested for the inner-core excited mixed rare-gas clusters from the analysis of the EICO peak width. The MHMI measurements give us direct evidence for the strong charge migration from X-ray absorbing atoms to surrounding atoms. The photon energy dependence of the PSD image for fragment ions suggests that the momentum of the fragment ions depends on the number of charges generated by the vacancy cascade