Ultramicroscopy

Items from 1 to 20 out of 26 results

article

Analysis conditions of an industrial Al-Mg-Si alloy by conventional and 3D atom probes

F. Danoix, M.K. Miller, A. Bigot

Ultramicroscopy > 2001 > 89 > 1-3 > 177-188

Industrial 6016 Al-Mg-Si(Cu) alloys are presently regarded as attractive candidates for heat treatable sheet materials. Their mechanical properties can be adjusted for a given application by age hardening of the alloys. The resulting microstructural evolution takes place at the nanometer scale, making the atom probe a well suited instrument to study it.Accuracy of atom probe analysis of these aluminium...

article

Fundamental new results in the energetics and thermodynamics of charged metal surfaces

Richard G. Forbes

Ultramicroscopy > 2001 > 89 > 1-3 > 1-5

There should be close scientific relationships between the following: the bonding energy of an atom or molecule at a curved surface; the Laplace-Young equation (the 'equation for pressure difference across a curved surface'); the Kelvin equation (the 'equation for vapour pressure above a curved surface'); and the thermodynamics of surface diffusion. This paper briefly reports some surprising new theoretical...

article

Field-induced electron emission from electrically nanostructured heterogeneous (ENH) materials

Richard G. Forbes

Ultramicroscopy > 2001 > 89 > 1-3 > 7-15

This paper discusses the origins of field-induced electron emission from thin films of electrically nanostructured heterogeneous (ENH) materials. Such materials exhibit low macroscopic field (LMF) electron emission: as thin films on a conducting substrate, they emit electrons into vacuum when LMFs, typically about 1-10V/μm, are applied. An ENH material comprises: a dielectric matrix, which may contain...

article

Study of the frequency response of the thin film cold cathode electron source of a lighting element

S.Z. Deng, F. Qian, N.S. Xu, Jun Chen

Ultramicroscopy > 2001 > 89 > 1-3 > 123-128

Details of the recent experimental and theoretical studies of the frequency characteristic of the field emission electron source of a lighting element are given. The response times at different frequencies (0.02-200kHz) and applied gap fields, acting on cathode surface, have been studied. A correlation has been found to exist between the response time and the frequency of applied voltage pulse. The...

article

Numerical modelling of mass resolution in a scanning atom probe

A. Cerezo, D. Vaumousse

Ultramicroscopy > 2001 > 89 > 1-3 > 155-161

We have recently suggested a novel method for improving mass resolution in the scanning atom probe (SAP), based on a post-deceleration scheme. A two-conductor counter electrode is used, and the high voltage pulse is applied to the front conductor, with the rear conductor being held at ground. For a separation between the two conductors of 100μm or less, ions travel between the two while the pulse...

article

A new approach to the interpretation of atom probe field-ion microscopy images

F. Vurpillot, A. Bostel, D. Blavette

Ultramicroscopy > 2001 > 89 > 1-3 > 137-144

The field distribution and the ion trajectories close to the tip surface are known to mainly control the contrast of field-ion microscopy and the resolution of the three-dimensional atom probe. The proper interpretation of images provided by these techniques requires the electric field and the ion trajectories to be determined accurately.A model has been developed in order to compute the ion trajectories...

article

Subnanometer three-dimensional atom-probe investigation of segregation at MgO/Cu ceramic/metal heterophase interfaces

J.T. Sebastian, J. Rüsing, O.C. Hellman, D.N. Seidman, more

Ultramicroscopy > 2001 > 89 > 1-3 > 203-213

Three-dimensional atom-probe (3DAP) microscopy has been applied to the study of segregation at ceramic/metal (C/M) interfaces. In this article, results on the MgO/Cu(X) (where X=Ag or Sb) systems are summarized. Nanometer-size MgO precipitates with atomically clean and atomically sharp interfaces were prepared in these systems by internal oxidation. Segregation of the ternary component (Ag or Sb)...

article

Prototypes using metal, carbon fiber and composite field emission sources modulated by a laser beam

M.S. Mousa, M. Brugat, E.P. Sheshin, M.J. Hagmann

Ultramicroscopy > 2001 > 89 > 1-3 > 129-135

Field emission of electrons from a variety of metallic, carbon fiber and composite metal-insulator micropoint cathodes was employed in this study. Tungsten, carbon fiber and ZrC tips, were studied using a field emission microscope. These cathodes were characterized and the current-voltage (I-V) characteristics were determined. A variety of surface treatment procedures were carried out to increase...

article

Nanometer-scale solute segregation at heterophase interfaces and microstructural evolution of molybdenum nitride precipitates

Dieter Isheim, Ellen J. Siem, David N. Seidman

Ultramicroscopy > 2001 > 89 > 1-3 > 195-202

The interrelationship between coherency and solute segregation at metal/metal-nitride heterophase interfaces is studied on a subnanometer scale by both atom-probe field-ion and electron microscopies for molybdenum nitride precipitates in Fe-2at% Mo-X, where X=0.4at% Sb or 0.5at% Sn. Internal nitridation at 550 ^o C generates thin platelet-shaped molybdenum nitride precipitates, while nitridation...

article

New results in the theory of Fowler-Nordheim plots and the modelling of hemi-ellipsoidal emitters

Richard G. Forbes, Kevin L. Jensen

Ultramicroscopy > 2001 > 89 > 1-3 > 17-22

This paper reports further progress in understanding the theory of emission-area extraction from Fowler-Nordheim plots, and reports some useful interim results derived by modelling field electron emission from hemi-ellipsoidal emitters. The mathematical nature of the relationship between a new approach to emission-area extraction, recently proposed, and older approaches is demonstrated. The new approach...

article

Relationships among the physical parameters required to give a linear relation between slope and intercept of Fowler-Nordheim plots

Yasuhito Gotoh, Hiroshi Tsuji, Junzo Ishikawa

Ultramicroscopy > 2001 > 89 > 1-3 > 63-67

For field emitters with a given surface condition, but different apex radii, there exists an empirical linear relationship between the slopes and intercepts of their Fowler-Nordheim plots. This behavior is quite different from that predicted by the theory with the assumption of a smooth surface. We have already characterized the possible reasons for this discrepancy; one possibility is that the emission...

article

Confinement of surface state electrons on Cu and Au field emitters

Toyo Sakata, Hideaki Fujioka, Akira Sakai

Ultramicroscopy > 2001 > 89 > 1-3 > 89-94

Field-emission images of clean Cu and Au emitters show a peculiar halo-like ring centered at the {111} pole. Typical diameter and width of the ring are ~10nm and ~2nm, respectively. Since we found no geometrical features around the {111} pole that gives rise to such a ring pattern, we interpreted the ring pattern as representing enhanced emission from an annular terrace that resonantly confines surface...

article

In situ dynamic study of hydrogen oxidation on rhodium

T. Visart de Bocarmé, T. Bär, N. Kruse

Ultramicroscopy > 2001 > 89 > 1-3 > 75-82

The reaction of hydrogen/oxygen gas mixtures with rhodium single crystals was studied using video-FIM (Field Ion Microscopy) at temperatures between 350 and 550K and up to 2x10 ^- ² Pa total pressure. Imaging at 500K in a hydrogen rich gas mixture (H ₂ :O ₂ =9) revealed considerable morphological changes of the (001)-oriented field emitter tip, i.e. the growth of low-index...

article

Analysis of fiber probes of scanning near-field optical microscope by field emission microscopy

S.K. Sekatskii, B.N. Mironov, D.A. Lapshin, G. Dietler, more

Ultramicroscopy > 2001 > 89 > 1-3 > 83-87

It is shown that field emission microscopy and related methods can be used to analyze the metal coated fiber tips, which nowadays are the most frequently used sensor for the scanning near-field optical microscopy (SNOM). Metal free and thus non field-emitting aperture for the light transmission on the tip apex can be directly seen and its parameters can be measured, which is very important for the...

article

Measurements of field enhancement introduced by a local electrode

M. Huang, A. Cerezo, P.H. Clifton, G.D.W. Smith

Ultramicroscopy > 2001 > 89 > 1-3 > 163-167

Direct measurements of field enhancement introduced by a local electrode have been carried out on a scanning atom probe (SAP). The results show that an enhancement factor of more than 2 can be obtained simply by reducing the specimen-to-electrode distance from 1.5mm to 10μm. Further enhancement can be achieved if the electrode has a smaller aperture. This suggests that a specimen with tip radius of...

article

On the increase of the intensity ratio of doubly charged ions to singly charged ions for liquid gold and copper ion sources

Yasuhito Gotoh, Hiroshi Tsuji, Junzo Ishikawa

Ultramicroscopy > 2001 > 89 > 1-3 > 69-74

The reason for the increase of R ₂ ₁ which is defined by the intensity ratio of the doubly charged ions to the singly charged ions, was studied. Based on the conventional field evaporation theory, an increase in the electric field and/or the source temperature is considered to be attributable. We took the fact that R ₂ ₁ turned to decrease at the higher current regime into...

article

Fabrication of specimens of metamorphic magnetite crystals for field ion microscopy and atom probe microanalysis

K.R. Kuhlman, R.L. Martens, T.F. Kelly, N.D. Evans, more

Ultramicroscopy > 2001 > 89 > 1-3 > 169-176

Field ion specimens have been successfully fabricated from samples of metamorphic magnetite crystals (Fe ₃ O ₄ ) extracted from a polymetamorphosed, granulite-facies marble with the use of a focused ion beam. These magnetite crystals contain nanometer-scale, disk-shaped inclusions making this magnetite particularly attractive for investigating the capabilities of atom probe field ion...

article

Modeling the electron field emission from carbon nanotube films

V. Filip, D. Nicolaescu, M. Tanemura, F. Okuyama

Ultramicroscopy > 2001 > 89 > 1-3 > 39-49

A theoretical framework for the electron field emission from carbon nanotubes (CNTs) is discussed. Using the tunneling theory, the influence of the detailed electron energy dispersion is proven to be of little importance for the electron field emission. By means of numerical computations in a simplified model, the influence of the environment on the local field on a CNT is discussed for an aligned...

article

Microfabrication and characterization of gated amorphous diamond-based field emission electron sources

N.S. Xu, J.C. She, S.E. Huq, Jian Chen, more

Ultramicroscopy > 2001 > 89 > 1-3 > 111-118

Gated field emission electron sources of amorphous diamond (a-D) coated Si tips and a-D diodes on a rough Si substrate were studied, detailing the deposition and characterization of the thin film, the fabrication processes and the emission behavior of the electron sources. Mechanisms responsible for the emission process of the a-D coated devices are proposed. A comparison of the field emission performance...

article

Comparison between experimental and computer simulations of current-voltage (I-V) characteristics of dielectric-coated photon-stimulated field emitters

Alexandre Mayer, M.S. Mousa, Jean-Pol Vigneron

Ultramicroscopy > 2001 > 89 > 1-3 > 95-104

For the purpose of simulating photon-stimulated field emission by taking account of three-dimensional aspects, a transfer-matrix formulation of electronic scattering was combined with a Floquet expansion of the wave function for taking account of quanta exchanges between the electrons and the external radiation. With specific techniques to preserve numerical stability, this transfer-matrix formalism...

Number:
1-3
Volume:
89
Year:
2001

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Keywords

[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 61.16.FK (4)
FIELD EMISSION (3)
ATOM PROBE (2)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 07.78.+S (2)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 41.20.-Q (2)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 41.75.-I (2)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 79.70 (2)
3D ATOM PROBE (1)
3DAP (1)
AL-MG-SI (1)
AMORPHOUS CARBON-NITRIDE FILM (1)
AMORPHOUS DIAMOND (1)
ANALYSIS CONDITIONS (1)
ATOM PROBE MICROANALYSIS (1)
ATOM-PROBE FIELD-ION MICROSCOPY (1)
CERAMIC/METAL (1)
CHARGED SURFACES (1)
CU-FE (1)
ELECTRON ENERGY SPECTRUM (1)
ELECTRON FIELD EMISSION (1)
FIELD DESORPTION IMAGE (1)
FIELD EMISSION DISPLAYS (1)
FIELD EMISSION ELECTRON SOURCE (1)
FIELD EMITTERS AND ARRAYS (1)
FIELD EVAPORATION (1)
FIELD ION MICROSCOPY (1)
FIELD-ION EMISSION (1)
FIELD-ION MICROSCOPE (1)
FIM (1)
FOCUSED ION BEAM (1)
FREQUENCY CHARACTERISTIC (1)
GATED ELECTRON SOURCE (1)
HETEROPHASE INTERFACES (1)
HREM (1)
INSTRUMENT CONTROL AND ALIGNMENT (1)
INTERNAL INTERFACES (1)
INTERNAL NITRIDATION (1)
LOCAL MAGNIFICATION (1)
MAGNETITE (1)
MECHANICAL ALLOYING (1)
MGO/CU (1)
MODELLING (1)
NANOCRYSTALLINE MATERIALS (1)
OXIDE (1)
PHASE COMPOSITION (1)
QUANTUM CONFINEMENT (1)
RESPONSE TIME (1)
SAMPLE PREPARATION (1)
SEGREGATION (1)
SIMULATION (1)
SOLUTE SEGREGATION (1)
SURFACE STATES (1)
THERMODYNAMICS (1)
THREE-DIMENSIONAL ATOM-PROBE MICROSCOPY (1)
TRANSMISSION ELECTRON MICROSCOPY (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 07.81 (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 61.72.FF (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 64.75.+G (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 68.35.-P (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 68.35.DV (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 73.20.AT (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 73.61 (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 75.50.BB (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 79.70.+Q (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 81.05.FE (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 81.05.YS (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 81.20.EV (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 85.45.D (1)
[PHYSICAL ASTRONOMY CLASSIFICATION SCHEME] 85.45.F (1)
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Ultramicroscopy

Analysis conditions of an industrial Al-Mg-Si alloy by conventional and 3D atom probes

Fundamental new results in the energetics and thermodynamics of charged metal surfaces

Field-induced electron emission from electrically nanostructured heterogeneous (ENH) materials

Study of the frequency response of the thin film cold cathode electron source of a lighting element

Numerical modelling of mass resolution in a scanning atom probe

A new approach to the interpretation of atom probe field-ion microscopy images

Subnanometer three-dimensional atom-probe investigation of segregation at MgO/Cu ceramic/metal heterophase interfaces

Prototypes using metal, carbon fiber and composite field emission sources modulated by a laser beam

Nanometer-scale solute segregation at heterophase interfaces and microstructural evolution of molybdenum nitride precipitates

New results in the theory of Fowler-Nordheim plots and the modelling of hemi-ellipsoidal emitters

Relationships among the physical parameters required to give a linear relation between slope and intercept of Fowler-Nordheim plots

Confinement of surface state electrons on Cu and Au field emitters

In situ dynamic study of hydrogen oxidation on rhodium

Analysis of fiber probes of scanning near-field optical microscope by field emission microscopy

Measurements of field enhancement introduced by a local electrode

On the increase of the intensity ratio of doubly charged ions to singly charged ions for liquid gold and copper ion sources

Fabrication of specimens of metamorphic magnetite crystals for field ion microscopy and atom probe microanalysis

Modeling the electron field emission from carbon nanotube films

Microfabrication and characterization of gated amorphous diamond-based field emission electron sources

Comparison between experimental and computer simulations of current-voltage (I-V) characteristics of dielectric-coated photon-stimulated field emitters

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