Administrator Portal
Persian German English


Anzahl der auf Ihren Besuch: 20
Anzahl der insgesamt zu besuchen: 10259


 
Artikel abstrakten
Artikel Autoren
Refrence
Autoren-Adresse

 
Artikel abstrakten
Artikel Autoren
Autor: K. Peithmann1 , M.R. Zamani-Meymian1 , M. Haaks1 , K. Maier1, B. Andreas2, K. Buse2, H. Modrow3
Refrence
Ref: Appl. Phys. B 82 (2006) 419
Autoren-Adresse
1 Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14–16, 53115 Bonn, Germany

 Direct visualization of damage cascades in lithium niobate crystals caused by high-energy ions
Artikel abstrakten
Abstract Congruently melting undoped lithium niobate crystals are irradiated with 20 MeV 3He ions which penetrate the entire crystal volume. Radiation damage effects are directly visualized by transmission electron microscopy (TEM) where damage zones with diameters of 4 nm give rise to circular Fresnel fringe contrasts. These regions of modified material, appearing circular in cross-section, are interpreted as damage cascades inflicted by fast Nb and O atoms displaced in knock-on collisions with primary 3He ions. This two-step displacement process results in local density changes manifested by the contrast behaviour of Fresnel fringes observed in TEM images.
Artikel Autoren
M R Zamani-Meymian1, K Peithmann1, K Maier1, H Schmid2 and W Mader2
Refrence
Ref: J. Phys.: Condens. Matter. 21 (2009) 075402
Autoren-Adresse
Affiliations1 Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14-16, D-53115 Bonn, Germany

 Thermal and long-term stability of fast-ion-irradiation-induced refractive index changes in lithium niobate crystals
Artikel abstrakten
Abstract Irradiation of congruently melting, nominally undoped lithium niobate crystals (LiNbO3) with high-energy, low-mass 3He ions, which are transmitted through the crystal, causes large and stable changes of the refractive index. In the irradiated regions, the extraordinary index is increased whereas the ordinary index is diminished. The decay of these changes upon annealing treatments up to 400°C is investigated, exhibiting a strongly non-monoexponential decay behaviour. Long-term measurements of the refractive index changes yield no pattern erasure on a timescale of four years.
Artikel Autoren
Mohammad-Reza Zamani-Meymian, Lena Jentjens, Niels L. Raeth, Konrad Peithmann and Karl Maier
Refrence
Ref: Appl. Phys. A: Materrials Science & Processing Vol. 98 (2010) 909
Autoren-Adresse
Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14-16, D-53115 Bonn, Germany

 Atomic displacement and disorder in LiNbO3 single crystal caused by high-energy 3He ion irradiation: an x-ray absorption spectroscopy study
Artikel abstrakten
Abstract Nb K-edge x-ray absorption fine structure spectra from a single lithium niobate (LN) crystal irradiated with high-energy 3He ions of 41 MeV and from unexposed crystal as the reference material are compared. The differences in the x-ray absorption near edge structure (XANES) spectra are interpreted by simulating Nb K-edge XANES spectra with the FEFF8.2 code. It is found that displacements of Nb and Li atoms, as well as Li and O vacancies, are likely to cause structural disorder leading to change in the refractive index of LN and to diminished birefringence. This finding is in agreement with previous results obtained from SRIM-2003 simulations and transmission electron microscopy measurements.
Artikel Autoren
AuthorT Vitova1, M R Zamani-Meymian2, K Peithmann2, K Maier2 and J Hormes1
Refrence
Ref: J. Phys.: Condensed Matter. Vol. 21 (2009) 495401
Autoren-Adresse
Affiliations1 Institute of Physics, University of Bonn, Nußallee 12, 53115 Bonn, Germany

 Oberflächenanalztik an Cäsiumbedeckten Metalloberflächen
Artikel abstrakten
Electrons work function change while solid surface atoms are covered by other particles. This change is caused the probability change of atom ionization. Covering of solid surface by electronegative (electropositive) atoms increases (decreases) the work function. In this paper experimentally examined the deposition of Cs on Ag & by measurement of layer thickness, the relation between the ionization probability of surface atoms with the thickness layers of Cs & is investigated. PACS No.: 73.00, 68.35
Artikel Autoren
Zamani Meymian, Mohammad Reza1;Wucher, Andreas2
Refrence
physics conference of iran 1390
Autoren-Adresse
1 Department of Physics, Iran University of Science and Technolog, Tehran

Alle Rechte vorbehalten