Effect of Multiple Scattering and Thermal Vibrations on the Reflection of Ions from the Face of a Single Crystal

Author(s):  
É. S. Parilis ◽  
N. Yu. Turaev ◽  
V. M. Kivilis
2016 ◽  
Vol 48 (2) ◽  
pp. 143-148
Author(s):  
Kittipong Seingsanoh ◽  
◽  
Pruittipol Limkitjaroenporn ◽  
Jakrapong Kaewkhao ◽  
◽  
...  

1968 ◽  
Vol 46 (6) ◽  
pp. 543-550 ◽  
Author(s):  
E. Uggerhøj ◽  
J. U. Andersen

The emission yield from single crystals doped with β emitters is investigated. In the axis direction, energetic electrons emitted from a lattice position show a peak in yield up to 2.4 times the normal yield, whereas positrons emitted from the same positions show a dip by a factor of 4 from the normal yield. Electrons emitted from interstitial positions show no peak in yield. Energetic electrons transmitted through a thin single crystal experience increased multiple scattering when the incoming beam is aligned with an axis direction. The influence of atomic planes on the motion of electrons and positrons is also investigated. Furthermore, the electron peak and positron dip have been used for the localization of foreign atoms in single crystals.


1997 ◽  
Vol 04 (03) ◽  
pp. 469-478 ◽  
Author(s):  
W. MORITZ ◽  
J. LANDSKRON ◽  
T. GRÜNBERG

The multiple scattering theory of LEED is briefly reviewed, and recent developments concerning the analysis of thermal vibrations with LEED and the analysis of lattice modulations in incommensurate layers are discussed. Usually only isotropic thermal vibrations have been considered in LEED structure analyses. This restriction can be overcome by an extension of the theory to anisotropic and anharmonic vibrations, allowing not only a higher precision in the determination of structure parameters but also the study of dynamical processes with LEED. In the case of incommensurate layers the satellite reflections arise from multiple diffraction as well as from modulations in the adsorbate or substrate lattice. It is shown that an approximation can be introduced in the multiple scattering formalism to calculate the satellite intensities. The method can be applied to incommensurate layers as well as to higher order commensurate layers.


2006 ◽  
Vol 62 (4) ◽  
pp. i103-i105 ◽  
Author(s):  
Akihiko Nakatsuka ◽  
Osamu Ohtaka ◽  
Hiroshi Arima ◽  
Noriaki Nakayama ◽  
Tadato Mizota

The crystal structure of the low-temperature (LT) modification of LaBO3 has been redetermined from single-crystal X-ray data; the resulting structure confirms the previous study [Abdullaev, Dzhafarov & Mamedov (1976). Azerbaidzhanskii Khim. Zh. pp. 117–120], but with improved precision. LT-LaBO3 crystallizes in space group Pnma and adopts the aragonite-type structure. Except for one O atom, which is situated on a general position, all other atoms (one La, one B and a second O atom) lie on mirror planes. The structure is composed of LaO9 polyhedra with an average La—O distance of 2.593 Å and trigonal BO3 groups with an average B—O distance of 1.373 Å. Slight anisotropies of the thermal vibrations of La and B atoms suggest that the electrostatic La...La and La...B interactions across the shared edges are weak.


Author(s):  
Дмитрий Петрович Бернацкий ◽  
Виктор Георгиевич Павлов

С помощью полевой десорбционной микроскопии исследована десорбция атомов цезия с квазисферической науглероженной поверхности монокристалла иридия. Получены полевые электронные и десорбционные изображения поверхности при образовании графена на грани (100) иридия. Полевые электронные изображения поверхности эмиттера до интеркалирования и после интеркалирования графена атомами цезия не изменяются. Электрическое поле стимулирует десорбцию атомов цезия из интеркалированного состояния, вследствие разрыва связей крайних атомов углерода с поверхностью грани (100) иридия. С помощью покадровой регистрации показана возможность наблюдения локализации дефектов графенового слоя на поверхности полевого эмиттера. Показано, что полевая десорбция атомов цезия из интеркалированного состояния начинается с дефектов графена расположенных по периметру островка графена. Обнаружено, что десорбционные центры могут располагаться не только по периметру графенового островка, но и в центральной его части в случае образования неупорядоченного графена. The desorption of caesium atoms from the quasi-spherical carbonized surface of an iridium single crystal was studied using the field desorption microscopy. Field electron and desorption images of the surface during the formation of graphene on the (100) iridium face are obtained. The field electron images of the emitter surface before intercalation and after intercalation of graphene with caesium atoms do not change. The electric field stimulates the desorption of caesium atoms from the intercalated state, due to the breaking of the bonds of the extreme carbon atoms with the surface of the face (100) of iridium. Using frame-by-frame recording, the possibility is shown of observing the localization of graphene layer defects on the surface of the field emitter. It is also shown that the field desorption of caesium atoms from the intercalated state begins with graphene defects located along the perimeter of the graphene island. It is found that desorption centers can be located not only along the perimeter of the graphene island, but also in its central part in the case of the disordered graphene formation.


Sign in / Sign up

Export Citation Format

Share Document