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 Titel: Refractive index changes in lithium niobate crystals by high-energy particle radiation
Article abstract
Abstract: Irradiation of lithium niobate crystals with 41 MeV 3He ions causes strong changes of the ordinary and extraordinary refractive indexes. We present a detailed study of this effect. Small fluence of irradiation already yields refractive index changes about 5×10-4; the highest values reach 3×10-3. These index modulations are stable up to 100°C and can be erased thermally, for which temperatures up to 500°C are required. A direct correlation between the refractive index changes and the produced lattice vacancies is found.
Article authors
Autor: K. Peithmann1 , M.R. Zamani-Meymian1 , M. Haaks1 , K. Maier1, B. Andreas2, I. Breunig2
Refrence
Ref: J. Opt. Soc. Am. B 23 (2006) 2107
Authors address
1 Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14–16, 53115 Bonn, Germany

 Titel: Fabrication of embedded waveguides in lithium-niobate crystals by radiation damage
Article abstract
Abstract: Irradiation of lithium-niobate crystals (LiNbO3) with fast, high-energy 3He ions changes the refractive index in the interaction region where the ions speed through the material. Thus an inhomogeneous flux density profile can be used for a tailored modification of the optical properties of LiNbO3 crystals, without employing ion implantation. A new method to fabricate embedded, polarization sensitive channel waveguides in LiNbO3 utilizing accelerated 3He ions with an energy of 40 MeV is demonstrated.
Article authors
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
Authors address
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
Article abstract
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.
Article authors
M R Zamani-Meymian1, K Peithmann1, K Maier1, H Schmid2 and W Mader2
Refrence
Ref: J. Phys.: Condens. Matter. 21 (2009) 075402
Authors address
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
Article abstract
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.
Article authors
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
Authors address
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
Article abstract
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.
Article authors
AuthorT Vitova1, M R Zamani-Meymian2, K Peithmann2, K Maier2 and J Hormes1
Refrence
Ref: J. Phys.: Condensed Matter. Vol. 21 (2009) 495401
Authors address
Affiliations1 Institute of Physics, University of Bonn, Nußallee 12, 53115 Bonn, Germany

 The probability changes of Ag surface Atoms Ionization by Cs deposition
Article abstract
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
Article authors
Zamani Meymian, Mohammad Reza1;Wucher, Andreas2
Refrence
physics conference of iran 1390
Authors address
1 Department of Physics, Iran University of Science and Technolog, Tehran

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