Potential of Ultra-High Resolution and Low Voltage Sem for Dynamic Experiments

1995 ◽  
Vol 404 ◽  
Author(s):  
E D Boyes
Keyword(s):  
Low Voltage ◽  
High Vacuum ◽  
High Sensitivity ◽  
Ceramic Substrate ◽  
Particle Migration ◽  
In Situ Experiments ◽  
Dynamic Experiments ◽  
Resolution Imaging ◽  
New Generation

AbstractA new generation of ultrahigh resolution scanning electron microscope (UHRSEM) is designed to explore the potential for higher resolution imaging and chemical microanalysis from more representative bulk samples. A <0.5nm probe at 30kV and <2.5nm at 1kV have been integrated with high sensitivity energy dispersive x-ray spectrometry (EDX) [1] and a high vacuum (<3×10−8mbar) heating stage (to >1000°C). The sensitivity of surface imaging is generally enhanced at low beam energies. With low voltages and digitally integrated fast scan techniques, conductive coating of an electrically non-conducting sample, such as a ceramic substrate, is no longer a pre-requisite for SEM, and this opens up new possibilities for minimally invasive dynamic in-situ experiments. This paper focuses on metal particle migration and sintering on a ceramic substrate.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Are major instrumental developments in TEM still to be Expected?

1988 ◽  
Vol 46 ◽  
pp. 646-647
Author(s):  
K.D. van der Mast ◽  
A.J. Koster
Keyword(s):  
Surface Science ◽  
New Technologies ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Analytical Instrument ◽  
Electron Efficiency ◽  
In Situ Experiments ◽  
New Ideas

In general instrumental developments are caused either by new application demands or by the availability of new technologies. If we investigate the trends in application demands, some predictions can be made safely: More and more the TEM will be used as an analytical instrument. The number of desired signals (detectors) will increase and the quality of the signals must be improved in terms of noise and electron efficiency. Examples are parallel collection EELS and Auger detectors (Kruit and Venables, 1988).The first experiments on coincidence techniques are also promising (Kruit et al, 1984) and exciting new ideas are investigated today. Besides this, another area of applications will probably become more important: surface science in situ experiments. Especially for this type of experiments it is difficult to transfer the specimen to another system without spoiling the experiment. So these applications will lead to an ultra high vacuum specimen environment - constructed in a way that many accessories necessary for surface experiments can be added: Ion guns, preparation chamber, knudsen cells etc.

scholarly journals Direct focus sensing and shaping for high-resolution multi-photon imaging in deep tissue

2021 ◽  
Author(s):  
Jianan Qu ◽  
ZHONGYA QIN ◽  
ZHENTAO SHE ◽  
CONGPING CHEN ◽  
WANJIE WU ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
High Sensitivity ◽  
Deep Tissue ◽  
Non Invasive ◽  
Mouse Cortex ◽  
Intact Brain ◽  
Resolution Imaging

High-resolution optical imaging of deep tissue in-situ such as the living brain is fundamentally challenging because of the aberration and scattering of light. In this work, we develop an innovative adaptive optics three-photon microscope based on direct focus sensing and shaping that can accurately measure and effectively compensate for both low- and high-order specimen-induced aberrations and recover near-diffraction-limited performance at depth. A conjugate adaptive optics configuration with remote focusing enables in vivo imaging of fine neuronal structures in the mouse cortex through the intact skull up to a depth of 750 um below pia, making high-resolution microscopy in cortex near non-invasive. Functional calcium imaging with high sensitivity and accuracy, and high-precision laser-mediated microsurgery through the intact skull were demonstrated. Moreover, we also achieved in vivo high-resolution imaging of the deep cortex and subcortical hippocampus up to 1.1 mm below pia within the intact brain.

In-Situ Tem Observations of Electron Beam-Stimulated Reactions in NiO Under Oxidizing and Reducing Atmospheres

1991 ◽  
Vol 235 ◽  
Author(s):  
M. I. Buckett ◽  
L. D. Marks
Keyword(s):  
Radiation Damage ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
In Situ Tem ◽  
Transmission Electron ◽  
In Situ Experiments ◽  
Damage Process ◽  
Electron Stimulated Desorption ◽  
Surface Environment

ABSTRACT:L: NiO surfaces have been the subject of numerous investigations using a wide variety of techniques, including transmission electron microscopy (TEM). The findings, however, remain inconclusive regarding the relative contributions of irradiation effects such as ballistic erosion, electron-stimulated desorption (ESD) and electron-stimulated reaction (ESR), especially at incident electron energies exceeding 100 keV. In earlier studies it was suggested that the surface environment played a significant role in the radiation damage process. In this study, the effect of the surface environment is further illustrated by in-situ experiments in controlled sample environments. NiO surfaces were irradiated with electrons, ranging in energy from 3 keV to 300 keV, and examined in-situ under ultra-high vacuum (UHV) conditions (10−10 Torr), as well as in controlled oxidizing (oxygen) and reducing (CO) atmospheres. The nature of the surface reactions and their contribution to the overall radiation damage process in the various energy regimes is examined.

In Situ Dynamic Experiments and Modeling in Multiscale Kinetics of Damage-Failure Transition

2015 ◽  
Vol 784 ◽  
pp. 476-483
Author(s):  
Oleg Naimark
Keyword(s):  
Blow Up ◽  
Dissipative Structures ◽  
Collective Modes ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
Scaling Effects ◽  
In Situ Experiments ◽  
Dynamic Experiments ◽  
Collective Modes Of Defects

Scaling regularities that reveal the power law statistics of fragmentation and self-similarity of damage-failure transitions are linked to specific type of critical phenomena in ensembles of typical mesoscopic defects – structural-scaling transition. Taking into account nonlinearity of damage-failure transition the scaling effects were explained as the consequence of subjection of damage kinetics to the intermediate asymptotical (self-similar) solution. This solution has the nature of multiscale blow-up dissipative structures, represents the set of collective modes of defects responsible for the damage localization stage. Original in-situ experiments supported the assumption concerning the role of multiscale blow-up collective modes of defects in qualitative different scenario of dynamic crack propagation, failure of shocked materials, fragmentation statistics.

scholarly journals ETEM Issues and Opportunities for Dynamic In-situ Experiments

2004 ◽  
Vol 12 (4) ◽  
pp. 24-27 ◽  
Author(s):  
Edward D. Boyes ◽  
Pratibha L. Gai
Keyword(s):  
High Vacuum ◽  
Chemical Reactor ◽  
Dynamic Processes ◽  
Liquid Environment ◽  
Transmission Electron ◽  
In Situ Experiments ◽  
Differential Pumping ◽  
High Vacuum Environment ◽  
Multiple Stages

Many dynamic processes do not occur in nature, science or industry in a typical TEM high (and sometimes not so high) vacuum environment. Dynamic in-situ data related to the real world need to be obtained under Controlled conditions of gas/vapor/liquid environment and temperature. In the ETEM (Environmental Transmission Electron Microscope), the specimen - but nothing much else - is shared between the chemical reactor on the horizontal axis and the vertical microscope column (Fig.1). The original Philips CM30 column is highly modified with pressure limiting apertures around the beam and multiple stages of differential pumping (Fig.2).

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Hetero-Epitaxy of Group Va Metals on Sapphire

1972 ◽  
Vol 30 ◽  
pp. 492-493
Author(s):  
J. E. O'Neal ◽  
J. J. Bellina ◽  
B. B. Rath
Keyword(s):  
Thermal Contact ◽  
High Vacuum ◽  
Electron Beam Evaporation ◽  
Ultra High Vacuum ◽  
Backing Plate ◽  
Sapphire Substrates ◽  
Deposition Parameters ◽  
Polishing Damage ◽  
Reflection Electron Diffraction

Thin films of the bcc metals vanadium, niobium and tantalum were epitaxially grown on (0001) and sapphire substrates. Prior to deposition, the mechanical polishing damage on the substrates was removed by an in-situ etch. The metal films were deposited by electron-beam evaporation in ultra-high vacuum. The substrates were heated by thermal contact with an electron-bombarded backing plate. The deposition parameters are summarized in Table 1.The films were replicated and examined by electron microscopy and their crystallographic orientation and texture were determined by reflection electron diffraction. Verneuil-grown and Czochralskigrown sapphire substrates of both orientations were employed for each evaporation. The orientation of the metal deposit was not affected by either increasing the density of sub-grain boundaries by about a factor of ten or decreasing the deposition rate by a factor of two. The results on growth epitaxy are summarized in Tables 2 and 3.

Low-voltage, high-resolution scanning electron microscopy of polymers

1987 ◽  
Vol 45 ◽  
pp. 466-467 ◽  
Author(s):  
S. J. Krause ◽  
W.W. Adams ◽  
S. Kumar ◽  
T. Reilly ◽  
T. Suziki
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Voltage ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Resolution Limit ◽  
Crossover Point ◽  
New Generation ◽  
Beam Damage ◽  
Scanning Electron

Scanning electron microscopy (SEM) of polymers at routine operating voltages of 15 to 25 keV can lead to beam damage and sample image distortion due to charging. Imaging polymer samples with low accelerating voltages (0.1 to 2.0 keV), at or near the “crossover point”, can reduce beam damage, eliminate charging, and improve contrast of surface detail. However, at low voltage, beam brightness is reduced and image resolution is degraded due to chromatic aberration. A new generation of instruments has improved brightness at low voltages, but a typical SEM with a tungsten hairpin filament will have a resolution limit of about 100nm at 1keV. Recently, a new field emission gun (FEG) SEM, the Hitachi S900, was introduced with a reported resolution of 0.8nm at 30keV and 5nm at 1keV. In this research we are reporting the results of imaging coated and uncoated polymer samples at accelerating voltages between 1keV and 30keV in a tungsten hairpin SEM and in the Hitachi S900 FEG SEM.

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