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Low-energy electron diffraction

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Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006655
EISBN: 978-1-62708-213-6
... Abstract Low-energy electron diffraction (LEED) is a technique for investigating the crystallography of surfaces and overlayers adsorbed on surfaces. This article provides a brief account of LEED, covering the principles and measurements of diffraction from surfaces. Some of the processes...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001769
EISBN: 978-1-62708-178-8
... Abstract Low-energy electron diffraction (LEED) is a technique for investigating the crystallography of surfaces and overlayers adsorbed on surfaces. This article describes the principles of diffraction from surfaces, and elucidates the method of sample preparation to achieve diffraction...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006660
EISBN: 978-1-62708-213-6
... is generally quite low. The low contrast is a result of the collection of not only the electrons that have diffracted from the sample but also the unintended but unavoidable collection of the electrons that have undergone larger energy-loss interactions. To compensate for the low contrast, there are...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006628
EISBN: 978-1-62708-213-6
... sample manipulator with stepping motors (custom made), (4 ) preamplifier, (5 ) amplifier, (6) four-channel multiple-stop time-to-digital converter (time resolution 10 ns), (7) pulse generator (100 kHz, 50 V), (8 ) low-energy electron diffraction (LEED) optics and Auger electron spectroscopy (AES...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006654
EISBN: 978-1-62708-213-6
.... 5 ), 1990 , p 387 – 391 , 10.1107/S0021889890005568 32. Macchi P. , Cryo-Crystallography: Diffraction at Low Temperature and More , Topics in Current Chemistry , Rissanen K. , Ed., Springer , Berlin, Heidelberg , 2011 , p 33 – 67 10.1007/128_2011_207 33...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001765
EISBN: 978-1-62708-178-8
... compensate for the low neutron flux on samples, instrumentation is being constructed to greatly increase the volume of diffraction space that can be sampled at one time. The single-crystal diffractometer at Argonne National Laboratory's Intense Pulsed Neutron Source, for example, has a 30- × 30-cm (12- × 12...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006667
EISBN: 978-1-62708-213-6
... corresponds to the start time for the TOF determination. In both reactor sources and spallation, the neutrons produced have too-high kinetic energy (fast neutrons) for scattering and must therefore be attenuated in moderators. These are reservoirs containing an appropriate low- Z material with weak...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006656
EISBN: 978-1-62708-213-6
..., but the signal-to-noise ratio will be low. Errors in diffraction ring positions due to instrument misalignment, improper calibration, and detector resolution can affect accuracy in the determination of d -spacings. With careful sample preparation and proper data collection and peak searching...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003251
EISBN: 978-1-62708-199-3
.... Phases formed by low-temperature deposition processes and solid state transformations, however, frequently have much finer grains whose sizes can be estimated from the widths of their diffraction peaks ( Fig. 9 ). Fig. 9 Effect of crystallite size on peak width. Source: Ref 1 Crystal...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001758
EISBN: 978-1-62708-178-8
... yield low values of R , generally from 0.02 to 0.07. If a proposed structure has the atoms placed near their correct positions, an R less than 0.40 should be obtained. A crude structural model can be improved if an electron density map is calculated using the observed structure amplitudes | F o...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006631
EISBN: 978-1-62708-213-6
... with the crystal. If the sample will be cooled, it is possible to use inert viscous liquids (e.g., motor or Vaseline oil), which will not crystallize at low temperatures. Then the crystalline sample should be placed for data collection into a single-crystal x-ray diffractometer. Today there are...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001757
EISBN: 978-1-62708-178-8
.... Measurements conducted using a Guinier camera implementing an internal-standard technique exhibit excellent reproducibility and precision. The camera is well suited to studying complex diffraction patterns of mixtures of phases and low-symmetry materials. The Guinier method is often the only technique for...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003528
EISBN: 978-1-62708-180-1
... strains, equivalent strains and stresses, etc.) The results identify high- and low-stressed areas and stress gradients. The locations with high priority for residual-stress measurements are the highest-tensile-stressed areas, that is, the areas that are most susceptible to localized yielding or...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006768
EISBN: 978-1-62708-295-2
... Berkley S.G. , Residual Stress Relaxation in Nickel Based Alloys Subjected to Low Cycle Fatigue , Proc. ICRS6 ( Oxford ), 2000 , p 144 – 151 54. Verpoort C.M. , and Gerdes C. , Shot Peening Theory and Application , IITT-International , 1989 , p 11 – 70 55. Berkley...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006638
EISBN: 978-1-62708-213-6
...-3_4 11. Newbury D.E. and Ritchie N.W.M. , Electron-Excited X-Ray Microanalysis at Low Beam Energy: Almost Always an Adventure! , Microsc. Microanal. , Vol 22 ( 4 ), 2016 , p 735 – 753 , 10.1017/S1431927616011521 12. Newbury D.E. and Ritchie N.W.M...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001766
EISBN: 978-1-62708-178-8
... the square of the incident-beam energy. Therefore, for a specified thickness of a given material, elastic scattering is more probable in high atomic number materials at low beam energy. Elastic scattering is responsible for both electron diffraction (thin foils) and the generation of backscattered...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006681
EISBN: 978-1-62708-213-6
... related to the square of the incident beam energy. Therefore, for a specific thickness of a given material, elastic scattering is more probable in high-atomic-number materials at low beam energy. Elastic scattering is responsible for both electron diffraction (thin foils) and the generation of BEs (bulk...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001770
EISBN: 978-1-62708-178-8
... to conduct elevated-temperature studies or to maintain a low vapor pressure for the sample. Some systems combine other techniques, such as XPS, SIMS, LEISS, low-energy electron diffraction (LEED), and reflection high-energy electron diffraction (RHEED), to obtain complementary information. Modem...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006657
EISBN: 978-1-62708-213-6
... XPS, energy-dispersive x-ray spectroscopy (EDS), secondary ion mass spectroscopy, low-energy ion-scattering spectroscopy, low-energy electron diffraction (LEED), and reflection high-energy electron diffraction, to obtain complementary information. Among the most common combination systems with AES are...
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001768
EISBN: 978-1-62708-178-8
... bookkeeping to avoid misidentifying low-intensity peaks as minor or trace elements when they are in fact higher order lines related to another parent peak. The multiplicity of diffraction orders can also lead to spectral interference. However, because x-rays of two different energies may be diffracted at the...