Low pH Chemical Etch Route for Smooth H-Terminated Si(100) And Study Of Subsequent Chemical Stability

1997 ◽  
Vol 477 ◽  
Author(s):  
B. J. Hinds ◽  
D. E. Aspnes ◽  
G. Lucovsky
Keyword(s):  
Optimal Solution ◽  
Native Oxide ◽  
Mechanistic Study ◽  
Ambient Conditions ◽  
Auger Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chemical Etch ◽  
Atomically Flat

ABSTRACTTo form atomically flat H-passivated Si(100) surfaces, wet chemical etching of sacrificial SiO2 layer has been examined. Roughness and chemical overlayer thickness, as monitored by ellipsometry shows a minima at an optimal solution of 1:0.5:30 HF(49wt\%):H2SO4 (98wt\%):H2O. A mechanistic study offers no evidence for a chemical smoothing from preferential non-Si(100) facet etching. Silicon planarization can be induced by rapid thermal annealing RTA of chemical oxides. The H-terminated Si(100) surfaces are found to be moderately reactive to ambient conditions as monitored by in-situ ellipsometry and Auger analysis. Atomic force microscopy (AFM) measurements show Si(100) surfaces to have a rms ∼1.0Å and Rmax values of 1.6–0.9Å. With measured roughness incorporate into ellipsometric model, a 5Å native oxide overlayer is rapidly incorporated into the Si(100) surface.

Chromic Polydiacetylene Single Crystals: Atomic Force Microscopy Studies

1995 ◽  
Vol 413 ◽  
Author(s):  
V. Shivshankar ◽  
C. Sung ◽  
J. Kumar ◽  
S. K. Tripathy ◽  
D. J. Sandman
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Morphology ◽  
Single Crystals ◽  
Ambient Conditions ◽  
Free Standing ◽  
Force Microscopy ◽  
Sensor Performance ◽  
Atomic Force ◽  
Variable Surface

ABSTRACTWe have studied the surface morphology of free standing single crystals of thermochromic polydiacetylenes (PDAs), namely, ETCD and IPUDO (respectively, the ethyl and isopropyl urethanes of 5,7-dodecadiyn-1,12-diol), by Atomic Force Microscopy (AFM) under ambient conditions. Micron scale as well as molecularly resolved images were obtained. The micron scale images indicate a variable surface, and the molecularly resolved images show a well defined 2-D lattice that is interpreted in terms of molecular models and known crystallographic data. Thereby information about surface morphology, which is crucial to potential optical device or chromic sensor performance is available. We also report the observation of a “macroscopic shattering” of the IPUDO monomer crystal during in-situ UV polymerization studies.

scholarly journals In situ characterization of nanoscale contaminations adsorbed in air using atomic force microscopy

2018 ◽  
Vol 9 ◽  
pp. 2925-2935 ◽  
Author(s):  
Jesús S Lacasa ◽  
Lisa Almonte ◽  
Jaime Colchero
Keyword(s):  
Atomic Force Microscopy ◽  
Ambient Conditions ◽  
Contact Potential ◽  
Force Microscopy ◽  
Multidimensional Spectroscopy ◽  
Atomic Force ◽  
Microscopy Techniques ◽  
Sample System

Under ambient conditions, surfaces are rapidly modified and contaminated by absorbance of molecules and a variety of nanoparticles that drastically change their chemical and physical properties. The atomic force microscope tip–sample system can be considered a model system for investigating a variety of nanoscale phenomena. In the present work we use atomic force microscopy to directly image nanoscale contamination on surfaces, and to characterize this contamination by using multidimensional spectroscopy techniques. By acquisition of spectroscopy data as a function of tip–sample voltage and tip–sample distance, we are able to determine the contact potential, the Hamaker constant and the effective thickness of the dielectric layer within the tip–sample system. All these properties depend strongly on the contamination within the tip–sample system. We propose to access the state of contamination of real surfaces under ambient conditions using advanced atomic force microscopy techniques.

Surface Stability of Siderite Under Acidic Atmosphere: an Atomic Force Microscopy Study

1996 ◽  
Vol 453 ◽  
Author(s):  
R. M. Weaver ◽  
D. E. Grandstaff ◽  
G. H. Myer
Keyword(s):  
Microscopy Study ◽  
Ambient Atmosphere ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Preferential Growth ◽  
Surface Stability ◽  
Force Microscopy ◽  
Atomic Force ◽  
Kinetics Of

AbstractThe reactivity of siderite (FeCO3) was investigated under ambient atmosphere and acidic aerosols using an atomic force microscope (AFM). Scans of freshly cleaved siderite crystals showed a relatively irregular microtopography, consisting of high-density kink-steps, compared to other isostructural carbonates (e.g. Iceland-spar calcite). Under ambient conditions siderite is inert with no spontaneous surface reconstruction as is reported for calcite. Under controlled conditions of pH and humidity, siderite was exposed to mists of HC1 and H2CO3 and the reaction was imaged with submicron resolution. The kinetics of the reaction varied with pH, humidity levels, and also as a function of the initial microtopography. Preferential growth and dissolution were observed as a function of initial topography and due to crystallographic anisotropies. Although extreme reaction conditions were excluded by certain aspects of AFM (high capillary forces, tip corrosion, charged surface), this technique has allowed real-time, in situ observations of surface reactions.

scholarly journals Ultrafine metal-polymer catalysts based on polyconjugated systems for Fisher–Tropsch synthesis

2020 ◽  
Vol 92 (6) ◽  
pp. 977-984
Author(s):  
Mayya V. Kulikova ◽  
Albert B. Kulikov ◽  
Alexey E. Kuz’min ◽  
Anton L. Maximov
Keyword(s):  
Tropsch Synthesis ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
Force Microscopy ◽  
Composite Catalysts ◽  
Fe Catalyst ◽  
Atomic Force ◽  
And Function ◽  
Metal Polymer

AbstractFor previously studied Fischer–Tropsch nanosized Fe catalyst slurries, polymer compounds with or without polyconjugating structures are used as precursors to form the catalyst nanomatrix in situ, and several catalytic experiments and X-ray diffraction and atomic force microscopy measurements are performed. The important and different roles of the paraffin molecules in the slurry medium in the formation and function of composite catalysts with the two types of aforementioned polymer matrices are revealed. In the case of the polyconjugated polymers, the alkanes in the medium are “weakly” coordinated with the metal-polymer composites, which does not affect the effectiveness of the polyconjugated polymers. Otherwise, alkane molecules form a “tight” surface layer around the composite particles, which create transport complications for the reagents and products of Fischer-Tropsch synthesis and, in some cases, can change the course of the in situ catalyst formation.

Atomic force microscopy of in situ deformed nickel thin films

1999 ◽  
Vol 353 (1-2) ◽  
pp. 194-200 ◽  
Author(s):  
C. Coupeau ◽  
J.F. Naud ◽  
F. Cleymand ◽  
P. Goudeau ◽  
J. Grilhé
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Force Microscopy ◽  
Nickel Thin Films ◽  
Atomic Force

scholarly journals Degradation Mechanism of Porous Metal-Organic Frameworks by In Situ Atomic Force Microscopy

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 722
Author(s):  
Ioanna Christodoulou ◽  
Tom Bourguignon ◽  
Xue Li ◽  
Gilles Patriarche ◽  
Christian Serre ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Degradation Mechanism ◽  
Metal Organic Frameworks ◽  
Porous Metal ◽  
Force Microscopy ◽  
Atomic Force ◽  
Metal Organic ◽  
The Media ◽  
Ph Conditions

In recent years, Metal-Organic Frameworks (MOFs) have attracted a growing interest for biomedical applications. The design of MOFs should take into consideration the subtle balance between stability and biodegradability. However, only few studies have focused on the MOFs’ stability in physiological media and their degradation mechanism. Here, we investigate the degradation of mesoporous iron (III) carboxylate MOFs, which are among the most employed MOFs for drug delivery, by a set of complementary methods. In situ AFM allowed monitoring with nanoscale resolution the morphological, dimensional, and mechanical properties of a series of MOFs in phosphate buffer saline and in real time. Depending on the synthetic route, the external surface presented either well-defined crystalline planes or initial defects, which influenced the degradation mechanism of the particles. Moreover, MOF stability was investigated under different pH conditions, from acidic to neutral. Interestingly, despite pronounced erosion, especially at neutral pH, the dimensions of the crystals were unchanged. It was revealed that the external surfaces of MOF crystals rapidly respond to in situ changes of the composition of the media they are in contact with. These observations are of a crucial importance for the design of nanosized MOFs for drug delivery applications.

In Situ Characterization of the Mechanical Behavior of Gecko's Spatulae by Atomic Force Microscopy

2013 ◽  
Vol 22 ◽  
pp. 85-93
Author(s):  
Shuang Yi Liu ◽  
Min Min Tang ◽  
Ai Kah Soh ◽  
Liang Hong
Keyword(s):  
Mechanical Behavior ◽  
Hierarchical Level ◽  
Intrinsic Properties ◽  
In Situ Characterization ◽  
Force Microscopy ◽  
Atomic Force ◽  
Theoretical Predictions ◽  
Multi Mode

In-situ characterization of the mechanical behavior of geckos spatula has been carried out in detail using multi-mode AFM system. Combining successful application of a novel AFM mode, i.e. Harmonix microscopy, the more detail elastic properties of spatula is brought to light. The results obtained show the variation of the mechanical properties on the hierarchical level of a seta, even for the different locations, pad and stalk of the spatula. A model, which has been validated using the existing experimental data and phenomena as well as theoretical predictions for geckos adhesion, crawling and self-cleaning of spatulae, is proposed in this paper. Through contrast of adhesive and craw ability of the gecko on the surfaces with different surface roughness, and measurement of the surface adhesive behaviors of Teflon, the most effective adhesion of the gecko is more dependent on the intrinsic properties of the surface which is adhered.

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