Growth of pentacene molecules on Tsai-type quasicrystals and related crystal surfaces

Recent progress in the electron-mirror microscopy (EMM), e.g., an improvement of its resolving power together with an increase of the magnification makes it useful for investigating the ferroelectric domain physics. English has recently observed the domain texture in the surface layer of BaTiO3. The present authors ) have developed a theory by which one can evaluate small one-dimensional electric fields and/or topographic step heights in the crystal surfaces from their EMM pictures. This theory was applied to a quantitative study of the surface pattern of BaTiO3).

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In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087616 ◽

1991 ◽

Vol 49 ◽

pp. 660-661

Author(s):

Z. L. Wang ◽

J. Bentley

Keyword(s):

High Temperatures ◽

Image Resolution ◽

Atomic Processes ◽

Crystal Surfaces ◽

Beam Radiation ◽

Surface Areas ◽

Transmission Electron ◽

Reflection Electron Microscopy ◽

Gas Reactions

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.

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Various technic for the measurement of step thickness on crystal surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109331 ◽

1978 ◽

Vol 36 (1) ◽

pp. 438-439

Author(s):

C. Boulesteix ◽

C. Colliex ◽

C. Mory ◽

B. Pardo ◽

D. Renard

Keyword(s):

Critical Thickness ◽

Symmetric Case ◽

Transmitted Intensity ◽

Crystal Surfaces ◽

Bright Field ◽

Excited Wave ◽

Highly Sensitive ◽

Contrast Mechanisms ◽

Step Thickness ◽

Thickness Variations

Contrast mechanisms, which are responsible of the various types of image formation, are generally thickness dependant. In the following, two imaging modes in the 100 kV CTEM are described : they are highly sensitive to thickness variations and can be used for quantitative estimations of step heights.Detailed calculations (1) of the bright-field intensity have been carried out in the 3 (or 2N+l)-beam symmetric case. They show that in given conditions, the two important symmetric Bloch waves interfere most strongly at a critical thickness for which they have equal emergent amplitudes (the more excited wave at the entrance surface is also the more absorbed). The transmitted intensity I for a Nd2O3 specimen has been calculated as a function of thickness t. The capacity of the method to detect a step and measure its height can be more clearly deduced from a plot of dl/Idt as shown in fig. 1.

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Surface reactions observed by photoemission electron microscopy (PEEM)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121831 ◽

1992 ◽

Vol 50 (1) ◽

pp. 286-287

Author(s):

H.H. Rotermund

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Work Function ◽

Chemical Reactions ◽

Reaction Diffusion ◽

Dynamic Processes ◽

Clean Surface ◽

Crystal Surfaces ◽

Single Crystal Surfaces ◽

Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

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Attractive mode force microscopy of chiral liquid crystal surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121740 ◽

1992 ◽

Vol 50 (1) ◽

pp. 268-269

Author(s):

B.D. Terris ◽

R. J. Twieg ◽

C. Nguyen ◽

G. Sigaud ◽

H. T. Nguyen

Keyword(s):

Liquid Crystal ◽

Crystal Surfaces ◽

Free Surfaces ◽

Control Range ◽

Force Microscopy ◽

Liquid Crystal Films ◽

Chiral Liquid Crystal ◽

Crystal Films ◽

Electrostatic Charging ◽

And Shifts

We have used a force microscope in the attractive, or noncontact, mode to image a variety of surfaces. In this mode, the microscope tip is oscillated near its resonant frequency and shifts in this frequency due to changes in the surface-tip force gradient are detected. We have used this technique in a variety of applications to polymers, including electrostatic charging, phase separation of ionomer surfaces, and crazing of glassy films.Most recently, we have applied the force microscope to imaging the free surfaces of chiral liquid crystal films. The compounds used (Table 1) have been chosen for their polymorphic variety of fluid mesophases, all of which exist within the temperature control range of our force microscope.

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Contrasts of planar defects in reflection electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015085x ◽

1993 ◽

Vol 51 ◽

pp. 1004-1005

Author(s):

Feng Tsai ◽

J. M. Cowley

Keyword(s):

Electron Microscopy ◽

Surface Defects ◽

Practical Importance ◽

Theoretical Treatment ◽

Crystal Surfaces ◽

Planar Defects ◽

Surface Steps ◽

Surface Reconstructions ◽

Domain Boundaries ◽

Reflection Electron Microscopy

Reflection electron microscopy (REM) has been used to study surface defects such as surface steps, dislocations emerging on crystal surfaces, and surface reconstructions. However, only a few REM studies have been reported about the planar defects emerging on surfaces. The interaction of planar defects with surfaces may be of considerable practical importance but so far there seems to be only one relatively simple theoretical treatment of the REM contrast and very little experimental evidence to support its predications. Recently, intersections of both 90° and 180° ferroelectric domain boundaries with BaTiO3 crystal surfaces have been investigated by Tsai and Cowley with REM.The REM observations of several planar defects, such as stacking faults and domain boundaries have been continued by the present authors. All REM observations are performed on a JEM-2000FX transmission electron microscope. The sample preparations may be seen somewhere else. In REM, the incident electron beam strikes the surface of a crystal with a small glancing angle.

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Effects of chemisorbed sulphur on the hydrogen adsorption and evolution on metal single crystal surfaces

Journal de Chimie Physique ◽

10.1051/jcp/1991881423 ◽

1991 ◽

Vol 88 ◽

pp. 1423-1452 ◽

Cited By ~ 36

Author(s):

E Protopopoff ◽

P Marcus

Keyword(s):

Single Crystal ◽

Hydrogen Adsorption ◽

Crystal Surfaces ◽

Single Crystal Surfaces ◽

Metal Single Crystal

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Electronic and Vibrational Properties of Single Crystal Surfaces of NiAl

MRS Proceedings ◽

10.1557/proc-83-47 ◽

1986 ◽

Vol 83 ◽

Author(s):

S.-C. Lui ◽

J. M. Mundenar ◽

E. W. Plummer ◽

M. E. Mostoller ◽

R. M. Nicklow ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Nearest Neighbor ◽

Surface States ◽

Active Surface ◽

Atomic Displacement ◽

Inelastic Electron ◽

Crystal Surfaces ◽

Single Crystal Surfaces ◽

Nial Alloy ◽

Bulk Surface

ABSTRACTSurface and bulk electronic structure of the ordered NiAl alloy were measured using angle resolved photoelectron spectroscopy. The measured bulk d-bands (Ni like) were observed to be narrower than theoretically calculated d band widths which are 20 to 40% wider (depending upon what is used as a measure of the width). At least two surface states were observed on both the (110) and (111) surfaces. The nature of these surface states and their relationship to the bulk band structure is discussed. Dispersion of bulk phonons was measured by neutron scattering and fitted with a fourth nearest neighbor Born-von Karman model. Dipole active surface phonons on the (110) and (111) surfaces were observed by inelastic electron scattering and the frequencies also calculated assuming a truncated bulk surface. The calculated surface modes present a qualitative picture of the atomic displacement at each surface and also show that the surface phonon energy and intensity depends upon the structure of the surface.

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