The Atomic-Scale Motion of Thiophene on Cu(111)

2014 ◽  
pp. 143-168
Author(s):  
Barbara A. J. Lechner
Keyword(s):  
Atomic Scale ◽  
Scale Motion

Dynamics of Electron and Photon Stimulated Desorption

1986 ◽  
Vol 68 ◽  
Author(s):  
R. E. Walkup ◽  
Ph. Avouris
Keyword(s):  
Crucial Role ◽  
Atomic Scale ◽  
Desorption Process ◽  
Trajectory Calculations ◽  
Positive Ions ◽  
Repulsive Interactions ◽  
Scale Motion ◽  
Electron And Photon

AbstractWe discuss specific examples of desorption due to electron or photon bombardment of solids, in which the repulsive interactions that result in particle expulsion can be clearly identified.A particularly interesting example is the desorption of positive ions from alkali-halides.Classical trajectory calculations are used to provide a picture of the atomic-scale motion during desorption.The results show that dynamic distortions of the lattice play a crucial role in the desorption process.

scholarly journals Imaging covalent bond formation by H atom scattering from graphene

Science ◽  
2019 ◽  
Vol 364 (6438) ◽  
pp. 379-382 ◽  
Author(s):  
Hongyan Jiang ◽  
Marvin Kammler ◽  
Feizhi Ding ◽  
Yvonne Dorenkamp ◽  
Frederick R. Manby ◽  
...  
Keyword(s):  
Bond Formation ◽  
Covalent Bond ◽  
Atomic Scale ◽  
Translational Energy ◽  
Elastic Channel ◽  
Atom Scattering ◽  
Covalent Bond Formation ◽  
Dynamics Simulations ◽  
Scale Motion ◽  
Intramolecular Vibrational Relaxation

Viewing the atomic-scale motion and energy dissipation pathways involved in forming a covalent bond is a longstanding challenge for chemistry. We performed scattering experiments of H atoms from graphene and observed a bimodal translational energy loss distribution. Using accurate first-principles dynamics simulations, we show that the quasi-elastic channel involves scattering through the physisorption well where collision sites are near the centers of the six-membered C-rings. The second channel results from transient C–H bond formation, where H atoms lose 1 to 2 electron volts of energy within a 10-femtosecond interaction time. This remarkably rapid form of intramolecular vibrational relaxation results from the C atom’s rehybridization during bond formation and is responsible for an unexpectedly high sticking probability of H on graphene.

Ultrafast X-ray measurements of inertial atomic-scale motion

2005 ◽  
Author(s):  
A.M. Lindenberg ◽  
K. Gaffney ◽  
J.B. Hastings ◽  
J. Larsson ◽  
O. Synnergren ◽  
...  
Keyword(s):  
Atomic Scale ◽  
X Ray ◽  
Scale Motion

High-Resolution Electron Microscopy of Grain Boundary Migration

2000 ◽  
Vol 652 ◽  
Author(s):  
K. L. Merkle ◽  
L. J. Thompson ◽  
Fritz Phillipp
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Elevated Temperatures ◽  
Boundary Migration ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Cooperative Effects ◽  
Resolution Electron ◽  
Scale Motion

ABSTRACTAtomic-scale grain boundary (GB) migration has been directly observed by high-resolution transmission electron microscopy (HREM). Atomic-scale motion of high-angle tilt GBs as well as twist and general GBs at gold island grains with a number of planar facets has been studied at ambient and elevated temperatures. GB migration mechanisms depend on GB structure and geometry. Strong indications for cooperative effects has been found. In this case, as has been proposed before, atoms may undergo small shifts in their lattice positions to be incorporated into the growing grain in a collective mode. At high temperature and in the absence of a strong driving force such small lattice regions are observed to fluctuate back and forth between the two grains. Faceted GBs typically move in spurts. This appears to be inherent to GB migration, whenever the motion is controlled by different structural entities. For some GB geometries the motion was found to proceed by the lateral propagation of atomic-scale steps.

Jumping, Rotating, and Flapping: The Atomic-Scale Motion of Thiophene on Cu(111)

2013 ◽  
Vol 4 (11) ◽  
pp. 1953-1958 ◽  
Author(s):  
Barbara A. J. Lechner ◽  
Marco Sacchi ◽  
Andrew P. Jardine ◽  
Holly Hedgeland ◽  
William Allison ◽  
...  
Keyword(s):  
Atomic Scale ◽  
Scale Motion

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

Structure and migration of planar defects in crystals observed in atomic scale

1978 ◽  
Vol 36 (1) ◽  
pp. 284-285 ◽  
Author(s):  
H. Hashimoto ◽  
Y. Sugimoto ◽  
Y. Takai ◽  
H. Endoh
Keyword(s):  
Electron Microscope ◽  
Rotation Angle ◽  
Crystal Surface ◽  
Electron Gun ◽  
Atomic Scale ◽  
Present Observation ◽  
Twist Boundary ◽  
Optical Magnification ◽  
Zinc Crystal ◽  
And Migration

As was demonstrated by the present authors that atomic structure of simple crystal can be photographed by the conventional 100 kV electron microscope adjusted at “aberration free focus (AFF)” condition. In order to operate the microscope at AFF condition effectively, highly stabilized electron beams with small energy spread and small beam divergence are necessary. In the present observation, a 120 kV electron microscope with LaB6 electron gun was used. The most of the images were taken with the direct electron optical magnification of 1.3 million times and then magnified photographically.1. Twist boundary of ZnSFig. 1 is the image of wurtzite single crystal with twist boundary grown on the surface of zinc crystal by the reaction of sulphur vapour of 1540 Torr at 500°C. Crystal surface is parallel to (00.1) plane and electron beam is incident along the axis normal to the crystal surface. In the twist boundary there is a dislocation net work between two perfect crystals with a certain rotation angle.

Resolution in the scanning tunneling microscope

1991 ◽  
Vol 49 ◽  
pp. 488-489
Author(s):  
R. J. Wilson ◽  
D. D. Chambliss ◽  
S. Chiang ◽  
V. M. Hallmark
Keyword(s):  
Scanning Tunneling Microscope ◽  
Fundamental Principle ◽  
Atomic Scale ◽  
Lateral Resolution ◽  
Scanning Tunneling ◽  
Electronic Noise ◽  
Vertical Resolution ◽  
Tunneling Microscopy ◽  
Spatial Profile ◽  
Theoretical Analyses

Scanning tunneling microscopy (STM) has been used for many atomic scale observations of metal and semiconductor surfaces. The fundamental principle of the microscope involves the tunneling of evanescent electrons through a 10Å gap between a sharp tip and a reasonably conductive sample at energies in the eV range. Lateral and vertical resolution are used to define the minimum detectable width and height of observed features. Theoretical analyses first discussed lateral resolution in idealized cases, and recent work includes more general considerations. In all cases it is concluded that lateral resolution in STM depends upon the spatial profile of electronic states of both the sample and tip at energies near the Fermi level. Vertical resolution is typically limited by mechanical and electronic noise.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

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