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in subjects: "Atomic Force Microscopy"

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The high-resolution architecture and structural dynamics of Bacillus spores

The capability to image single microbial cell surfaces at nanometer scale under native conditions would profoundly impact mechanistic and structural studies of pathogenesis, immunobiology, environmental resistance and biotransformation. We report here that advances in atomic force microscopy (AFM) have allowed us to directly visualize high-resolution native structures of bacterial endospores, including the exosporium and spore coats of four Bacillus species in air and water environments. The di… more

Date: May 6, 2004

Creator: Plomp, M; Leighton, T J; Wheeler, K E & Malkin, A J

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Observation of Localized Corrosion of Ni-Based Alloys Using Coupled Orientation Imaging Microscopy and Atomic Force Microscopy

We present a method for assessing the relative vulnerabilities of distinct classes of grain boundaries to localized corrosion. Orientation imaging microscopy provides a spatial map which identifies and classifies grain boundaries at a metal surface. Once the microstructure of a region of a sample surface has been characterized, a sample can be exposed to repeated cycles of exposure to a corrosive environment alternating with topographic measurement by an atomic force microscope in the same regi… more

Date: November 24, 1999

Creator: Bedrossian, P. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modeling of the Deformation of Living Cells Induced by Atomic Force Microscopy

We describe finite element modeling of the deformation of living cells by atomic force microscopy (AFM). Cells are soft systems, susceptible to large deformations in the course of an AFM measurement. Often the local properties, the subject of the measurement, are obscured by the response of the cell as a whole. The Lagrangian finite deformation model we have developed and implemented in finite elements analysis offers a solution to this problem. The effect of the gross deformation of the cell c… more

Date: December 21, 2001

Creator: Rudd, Robert E.; McElfresh, Michael; Baesu, Eveline; Balhorn, Rod; Allen, Michael J. & Belak, James

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Cross-Sectional Conductive Atomic Force Microscopy of CdTe/CdS Solar Cells: Effects of Etching and Back-Contact Processes; Preprint

We investigated the effects of the etching processes using bromine and nitric-phosphoric acid solutions, as well as of Cu, in the bulk electrical conductivity of CdTe/CdS solar cells using conductive atomic force microscopy (C-AFM). Although the etching process can create a conductive layer on the surface of the CdTe, the layer is very shallow. In contrast, the addition of a thin layer of Cu to the surface creates a conductive layer inside the CdTe that is not uniform in depth, is concentrated … more

Date: May 1, 2006

Creator: Moutinho, H. R.; Dhere, R. G.; Jiang, C.-S.; Gessert, T. A.; Duda, A. M.; Young, M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A Chemical Approach to 3-D Lithographic Patterning of Si and GeNanocrystals

Ion implantation into silica followed by thermal annealingis an established growth method for Si and Ge nanocrystals. Wedemonstrate that growth of Group IV semiconductor nanocrystals can besuppressed by co-implantation of oxygen prior to annealing. For Sinanocrystals, at low Si/O dose ratios, oxygen co-implantation leads to areduction of the average nanocrystal size and a blue-shift of thephotoluminescence emission energy. For both Si and Ge nanocrystals, atlarger Si/O or Ge/O dose ratios, the … more

Date: December 12, 2005

Creator: Sharp, I. D.; Xu, Q.; Yi, D. O.; Liao, C. Y.; Ager, J. W., III; Beeman, J. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Reversible wetting of NaCl nanoparticles at relative humidities below deliquescence observed by environmental non-contact AFM

The behavior of NaCl nanoparticles as a function of relative humidity (RH) was characterized by depositing particles on a prepared hydrophobic surface and measuring their height via non-contact environmental atomic force microscopy (AFM). Non-contact AFM allows greater sensitivity to changes in the size of particles than does contact AFM or scanning electron microscopy, and greater sensitivity to changes in shape than do mass-based techniques. Crystalline cubic NaCl nanoparticles with sides of … more

Date: December 14, 2009

Creator: Bruzewicz, D.A.; Lewis, E.; Ocko, B. M.; McGraw, R. L. & Schwartz, S. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

SEISMIC AND ROCK PHYSICS DIAGNOSTICS OF MULTISCALE RESERVOIR TEXTURES

As part of our study on ''Relationships between seismic properties and rock microstructure'', we have studied (1) How to quantify elastic properties of clay minerals using Atomic Force Acoustic Microscopy. We show how bulk modulus of clay can be measured using atomic force acoustic microscopy (AFAM) (2) We have successfully measured elastic properties of unconsolidated sediments in an effort to quantify attributes for detection of overpressures from seismic (3) We have initiated efforts for vel… more

Date: May 1, 2002

Creator: Mavko, Gary

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Periodic arrays of pinning centers in thin vanadium films.

Commensurability effects between the superconducting flux line lattice and a square lattice (period d=1{micro}m and diameter D=0.4{micro}m) of submicron holes in 1500 {angstrom} vanadium films were studied by atomic force microscopy, DC magnetization, AC susceptibility, magnetoresistivity and I-V measurements. Peaks in the magnetization and critical current at matching fields are found to depend nonlinearly upon the value of external AC field or current, as well as the inferred symmetry of the … more

Date: July 13, 1997

Creator: Brueck, S. R. J.; Chung, K.; Crabtree, G.; DeLong, L. E.; Hesketh, P. J.; Ilic, B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Identification and Characterization of a Human DNA Double-Strand Break Repair Complex

The authors have used atomic force microscopy (AFM) to characterize the assembly and structure of the macromolecular assemblies involved in DNA repair. They have demonstrated using AFM that the DNA-dependent protein kinase can play a structural role in the repair of DNA double-strand breaks (DSBs) by physically holding DNA ends together. They have extended these studies to include other DNA damage response proteins, these efforts have resulted in important and novel findings regarding the ATM p… more

Date: July 12, 1999

Creator: Chen, D. J. & Cary, R. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Mechanistic study of dielectric chemical mechanical polishing by spectral and scaling analysis of atomic force microscope images

Thermal oxide and PETEOS oxide surfaces, polished on an IPEC 472 with different combinations of polish pad, slurry, and polishing conditions, were studied with ex situ atomic force microscopy. The post polish surfaces were analyzed qualitatively by visual inspection and quantitatively by spectral and scaling analyses. Spectral and scaling analyses gave consistent interpretations of morphology evolution. Polishing with either a fixed abrasive pad or alumina-based slurry occurred via a mechanism … more

Date: December 22, 1999

Creator: Verhoff, M.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Vibrational spectra of nanowires measured using laser doppler vibrometry and STM studies of epitaxial graphene : an LDRD fellowship report.

A few of the many applications for nanowires are high-aspect ratio conductive atomic force microscope (AFM) cantilever tips, force and mass sensors, and high-frequency resonators. Reliable estimates for the elastic modulus of nanowires and the quality factor of their oscillations are of interest to help enable these applications. Furthermore, a real-time, non-destructive technique to measure the vibrational spectra of nanowires will help enable sensor applications based on nanowires and the use… more

Date: September 1, 2009

Creator: Biedermann, Laura Butler

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Conductive Atomic Free Microscopy of CdTe/CdS Solar Cells

Conductive atomic force microscopy (C-AFM) is a recently developed technique that applies an electric voltage between a very sharp tip and the sample, permitting the study of the electrical properties of the sample with very high spatial resolution. It also provides current-voltage measurements at well-defined spots. C-AFM is applied simultaneously with atomic force microscopy, providing topographic and current images of the same region. In this work, we analyze CdTe/CdS samples, before and aft… more

Date: January 1, 2005

Creator: Moutinho, H. R.; Dhere, R. G.; Jiang, C. S.; Al-Jassim, M. M. & Kazmerski, L. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mechanochromism, Shear Force Anisotropy, and Molecular Mechanics in Polydiacetylene Monolayers

The authors use scanning probe microscopy to actuate and characterize the nanoscale mechanochromism of polydiacetylene monolayer on atomically-flat silicon oxide substrates. They find explicit evidence that the irreversible blue-to-red transformation is caused by shear forces exerted normal to the polydiacetylene polymer backbone. The anisotropic probe-induced transformation is characterized by a significant change in the tilt orientation of the side chains with respect to the surface normal. T… more

Date: August 14, 2000

Creator: Burns, Alan R.; Carpick, R. W.; Sasaki, Darryl Y.; Shelnutt, John A. & Haddad, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mechanical and Electrical Properties of CdTe Tetrapods Studied byAtomic Force Microscopy

The mechanical and electrical properties of CdTe tetrapod-shaped nanocrystals have been studied with atomic force microscopy. Tapping mode images of tetrapods deposited on silicon wafers revealed that they contact the surface with the ends of three arms. The length of these arms was found to be 130 {+-} 10 nm. A large fraction of the tetrapods had a shortened vertical arm as a result of fracture during sample preparation. Fracture also occurs when the applied load is a few nanonewtons. Compress… more

Date: August 30, 2007

Creator: Fang, Liang; Park, Jeong Young; Cui, Yi; Alivisatos, Paul; Shcrier, Joshua; Lee, Byounghak et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Bacillus atrophaeus Outer Spore Coat Assembly and Ultrastructure

Our previous atomic force microscopy (AFM) studies successfully visualized native Bacillus atrophaeus spore coat ultrastructure and surface morphology. We have shown that the outer spore coat surface is formed by a crystalline array of {approx}11 nm thick rodlets, having a periodicity of {approx}8 nm. We present here further AFM ultrastructural investigations of air-dried and fully hydrated spore surface architecture. In the rodlet layer, planar and point defects, as well as domain boundaries, … more

Date: November 21, 2005

Creator: Plomp, M; Leighton, T J; Wheeler, K E; Pitesky, M E & Malkin, A J

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Heavy-Ion Irradiation of Thulium(III) Oxide Targets Prepared by Polymer-Assisted Deposition

Thulium(III) oxide (Tm{sub 2}O{sub 3}) targets prepared by the polymer-assisted deposition (PAD) method were irradiated by heavy-ion beams to test the method's feasibility for nuclear science applications. Targets were prepared on silicon nitride backings (thickness of 1000 nm, 344 {micro}g/cm{sup 2}) and were irradiated with an {sup 40}Ar beam at laboratory frame energy of {approx}210 MeV (50 particle nA). The root mean squared (RMS) roughness prior to irradiation is 1.1 nm for a {approx}250 n… more

Date: September 15, 2008

Creator: Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, Tashi; Ashby, Paul D.; Gates, Jacklyn M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Influence of Reaction with XeF2 on Surface Adhesion of Al and Al2O3 Surfaces

The change of surface adhesion after fluorination of Al and Al{sub 2}O{sub 3} surfaces using XeF{sub 2} was investigated with atomic force microscopy. The chemical interaction between XeF{sub 2} and Al and Al{sub 2}O{sub 3} surfaces was studied by in situ x-ray photoelectron spectroscopy. Fresh Al and Al{sub 2}O{sub 3} surfaces were obtained by etching top silicon layers of Si/Al and Si/Al{sub 2}O{sub 3} with XeF{sub 2}. The surface adhesion and chemical composition were measured as a function … more

Date: July 28, 2008

Creator: Zhang, Tianfu; Park, Jeong Y.; Huang, Wenyu & Somorjai, Gabor A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Towards Understanding the Mechanism of PETN Coarsening

The long-term goal is to determine the mechanism of PETN crystallization and coarsening at the solid-vapor interface and to quantify the thermodynamic and kinetic parameters that control those processes. We achieve this goal by investigating the surface evolution of synthetic PETN single crystals using in situ atomic force microscopy (AFM) at various temperatures.

Date: March 23, 2005

Creator: Qiu, R.; Overturf, G.; Gee, R.; Burnham, A.; Weeks, B. & De Yoreo, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Subsurface damage assessment with atomic force microscopy

The performance of transparent optics in high fluence applications is often dominated by inhomogeneities in the first few hundred nanometers of material. Defects undetectable with optical methods can cause catastrophic failures when used in critical applications where high strength, chemical or mechanical resistance or extreme smoothness is required. Not only are these defects substantially smaller than the wavelength of visible light, they are often concealed below a layer of glass-like materi… more

Date: April 16, 1999

Creator: Carr, J W; Fearon, E; Hutcheon, I D & Summers, L J

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

DNA Compaction by Yeast Mitochondrial Protein ABF2p

We used high resolution Atomic Force Microscopy (AFM) to image compaction of linear and circular DNA by the yeast mitochondrial protein ABF2p , which plays a major role in maintaining mitochondrial DNA. AFM images show that protein binding induces drastic bends in the DNA backbone for both linear and circular DNA. At high concentration of ABF2p DNA collapses into a tight globular structure. We quantified the compaction of linear DNA by measuring the end-to-end distance of the DNA molecule at in… more

Date: May 9, 2003

Creator: Friddle, R W; Klare, J E; Noy, A; Corzett, M; Balhorn, R; Baskin, R J et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Modeling AFM Induced Mechanical Deformation of Living Cells

Finite element modeling has been applied to study deformation of living cells in Atomic Force Microscopy (AFM) and particularly Recognition Force Microscopy (RFM). The abstract mechanical problem of interest is the response to RFM point loads of an incompressible medium enclosed in a fluid membrane. Cells are soft systems, susceptible to large deformations in the course of an RFM measurement. Often the local properties such as receptor anchoring forces, the reason for the measurement, are obscu… more

Date: November 15, 2002

Creator: Rudd, Robert E.; McElfresh, Michael; Balhorn, Rod; Allen, Michael J. & Belak, James

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Growth and Structure of Metallic Barrier Layer and Interconnect Films I: Experiments

We present experimented results directed at understanding the growth and structure of metallic barrier layer and interconnect films. Numerical simulation results associated with this experimental work are presented in an accompanying paper in these proceedings. Here, thin films of Al, Ti, Cu and Ta have been grown by magnetron sputtering onto oxidized Si substrates. Using a specially-constructed substrate holder, the orientation of the substrate with respect to the growth direction was varied f… more

Date: April 5, 1999

Creator: Baumann, F.H.; Gilmer, G.H.; O'Sullivan, P.L.; Sapjeta, J.; Torre, J.D. & Windt, D.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

MATERIALS WITH COMPLEX ELECTRONIC/ATOMIC STRUCTURES

We explored both experimentally and theoretically the behavior of materials at stresses close to their theoretical strength. This involves the preparation of ultra fine scale structures by a variety of fabrication methods. In the past year work has concentrated on wire drawing of in situ composites such as Cu-Ag and Cu-Nb. Materials were also fabricated by melting alloys in glass and drawing them into filaments at high temperatures by a method known as Taylor wire technique. Cu-Ag microwires ha… more

Date: September 1, 2000

Creator: PARKIN, D. M.; CHEN, L. & AL, ET

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Nanostructured Arrays Formed by Finely Focused Ion Beams

Amorphous, polycrystalline, and single crystal nanometer dimension particles can be formed in a variety of substrates by ion implantation and subsequent annealing. Such composite colloidal materials exhibit unique optical properties that could be useful in optical devices, switches, and waveguides. However colloids formed by blanket implantation are not uniform in size due to the nonuniform density of the implant, resulting in diminution of the size dependent optical properties. The object of t… more

Date: November 30, 1998

Creator: Budai, J. D.; Datsos, P. G.; Feldman, L. C.; Heinig, K. H.; Meldrum, A.; Strobel, M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department