Shinsuke Fujiwara

Position-dependent stopping powers of the (100) surfaces of NaCl-type crystals for MeV light ions

Abstract Energy losses of MeV H and He ions after interaction of clean surfaces of several NaCl-type crystals at glancing-angle of incidence are investigated. From the most probable energy losses of ions reflected from the surface atomic plane, position-dependent stopping powers of the (100) surfaces of NaCl, KCl, KBr, SnTe, PbSe and PbTe for MeV H and He ions are determined. The results are explained by a sum of the stopping caused by dynamic response of valence electrons to fast ions in vacuum and that due to single ion-electron collisions.

Archaeon Pyrococcus kodakaraensis KOD1: application and evolution

Archaea is the third domain which is phylogenetically differentiated from the other two domains, bacteria and eucarya. Hyperthermophile within the archaea domain has evolved most slowly retaining many ancestral features of higher eukaryotes. Pyrococcus kodakaraensis KOD1, which grows at 95 degrees C optimally, is a newly isolated hyperthermophilc archaeon. The KOD1 strain possesses a circular genome, whose size is estimated to be approximately 2,036 kb. KOD1 enzymes involved in the genetic information processing system, such as DNA polymerase, Rec protein, aspartyl tRNA synthetase and molecular chaperonin, share features of eukaryotic enzymes. Rapid and accurate PCR method by KOD1 DNA polymerase and enzyme stabilization system by KOD1 chaperonin are also introduced in this article.

Energy Losses of 12-32 keV H^+, He^+ and N^+ Ions at Glancing Angle Scattering from Clean Surfaces of Silicon Crystals

The energy spectra of scattered ions of 12–32 keV H + , He + and N + have been measured at glancing angle incidence on the clean (001) and (111) surfaces of Si. A similar formula of the position-dependent stopping power which has been derived for high energy light ions was used to analyze the present results of low energy ions.

Process of epitaxial growth of PbSe on SnTe (001) studied by glancing angle scattering of MeV He ions

Abstract Process of epitaxial growth of PbSe on SnTe (001) under UHV condition is studied with the use of glancing angle scattering of MeV He ions and transmission electron microscopy. An empirical relationship of the mean separation of misfit dislocations on the PbSe/SnTe interface and the thickness of the layer is derived from TEM observation. Anomalous broadening of the angular distribution of scattered He ions from the surface of PbSe is observed when the thickness of the PbSe layer is between 1 and about 20 nm. From the simulation of ion trajectories at glancing angle scattering from several model surfaces, this anomaly is attributed to the surface wrinkles caused by a square-net of misfit edge dislocations.

Position-dependent charge-exchange and energy-loss processes for MeV He ions near a crystal surface

Abstract Inelastic interaction of fast ions at glancing angles of incidence on a low index crystal surface is described by the probabilities, which depend on the distance of the ion from the surface; the charge state and energy distributions of the scattered ions are found to result from position-dependent interactions along their trajectories in vacuum. A stochastic equation to describe the charge exchange and energy loss of specularly reflected ions is proposed. Taking account of ion scattering at surface steps, the theory is applied to derive the position-dependent probabilities of electron loss and electron capture of MeV ions from the observed charge state and energy distributions of the scattered ions at glancing angle incidence on the (100) surface of SnTe.