Ex-situ and in-situ studies were performed for self-assembled monolayers (SAMs) formation on mica. The behavior of two surfactants [octadecylphosphonic acid (OPA) and dodecylphosphonic acid (DPA)] in two different solutions [ethanol or tetrahydrofuran (THF)] were studied at different concentrations. A cross section analysis of the monolayer images at partial coverage showed thickness of 1.8 nm, 0.7 nm, and 1.0 nm for OPA, DPA and mixed OPA/DPA, respectively. These values are similar to the ones presented by Xiao and those expected for a monolayer of mixed surfactants as proposed by Whitesides. Since the topography of a monolayer resembles the substrate, the presence of the monolayer at full coverage was determinated by force-distance curve measurements. It was observed that the solvent had the ability to re-dissolve the OPA monolayer, suggesting that the bonding is of a physisorption nature.

The atomic force microscope (AFM) is now a fairly widely used metrological tool for measuring surfaces with nanometer-scale precision, in 3-D. A number of biologists have noticed that untreated biological cells and molecules deposited onto surfaces can also be analyzed by AFM in air or fluids provided the AFM imaging forces do not greatly excede the compressiblity of the specimen. What has gone largely unnoticed in the biological microscopy community is the fact that AFM provides a wealth of opportunity with regard to 3D, nanometer-scale morphometric and biochemical measurements of biomaterials, cells and molecules. The ability to obtain such precise length-scale measurements on biological structures does open up a whole new branch of biological microscopy- something we have termed, Biometrology. A broad definition of Biometrology is, the science of quantifying biological structures such that the measured quantities give rise to biological or diagnostic information.

The AFM (atomic force microscopy) requires a stable and flat substrate on which a biological sample is readily immobilized. For instance, membrane protein 2D crystals in lipid bilayers have been adsorbed to silanized glass with covalently attachment using a photocrosslinker or to mica by physisorption under appropriate ionic conditions. For the immobilization of 2D crystals of water soluble proteins formed on lipid monolayers, a different approach is required to attach the highly hydrophobic tails of the lipid molecules. To find a suitably hydrophobic substrate, the hydrophobicity of different materials was determined by the sitting drop method. Briefly, a 10 μ1 droplet of deionized and filtered water was deposited on the substrate surface and the diameter measured. Table 1 shows a decrease in droplet diameter with increasing hydrophobicity, indicating that substrates such as silanized glass and HOPG (highly ordered pyrolytic graphite) may be suitable for adsorbing lipid monolayers.

Photoelastic measurement is a sensitive optical technique to map strain fields in otherwise isotropic materials. To extend this method to the submicron scale, we combine dynamic polarimetry with nearfield scanning optical microscopy (NSOM) and construct a polarization modulation NSOM (PMNSOM). The 670 nm laser light passes first through a linear polarizer (oriented at 90°), and then through a photoelastic modulator (PEM), and finally through a quarter wave plate. The PEM introduces a sinusoidally time varying phase shift δ0sin(2πft) into the +45° polarization component, where the modulation frequency/is the resonant frequency (50 kHz) of the PEM quartz element. The quarter wave plate (oriented at 0°) transforms this elliptically polarized light into linearly polarized light with its orientation varying sinusoidally at the modulation frequency. This polarized light is then coupled into a single-mode optical fiber leading to the NSOM tip.

Atomic force microscopy (AFM) was introduced in 1984, and proved to be more versatile than scanning tunneling microscopy (STM) due to the AFM's capabilities to scan non-conductive samples under atmospheric conditions and achieve atomic resolution. Ultra high vacuum (UHV) AFM has been used in surface science applications when control of oxidation and corrosion of a sample's surface are required. Expensive equipment and time consuming sample exchanges are two drawbacks of the UHV AFM system that limit its use. Until recently, no hot/cryo-stage, moderate vacuum, controlled gas environment AFM was commonly available.

We have demonstrated that phase transformations are easily observable in metal alloys and polymers with the use of a moderate vacuum AFM that has in-situ heating/cooling capabilities and quick (within minutes) sample exchange times. This talk will describe the results of experiments involving a wide range of samples designed to make use of the full capabilities of a hot/cryo-stage, controlled gas environment AFM.

Gold is an important mineral whether for its value, properties or its natural beauty. It is expected that in a few years Australia will be the second largest producer of gold. Present gold mining practices, though able to recover minute amounts of gold, can be improved. In the current process, gold is dissolved in an alkaline cyanide solution to form Au(CN)2, which is adsorbed onto activated carbon. Activated carbon has shown a special affinity for the gold complex even in the presence of other metalcyanide complexes at much greater concentrations in the pulp. This process is efficient and is able to recover gold at a concentration of 1 part per million in the auriferous ore. The adoption of the carbon technology has contributed substantially to the increased output of Australian gold. Within 15 years, local production has increased more than ten-fold over.

Nanoindentation is becoming an increasingly important tool for the characterization of the mechanical properties of materials on the nanometer scale. The mechanical response of a material is measured by recording the force acting between an indenter and the material while displacing the indenter into the material. The shape of the recorded load displacement curves is not only dependent on the mechanical properties of the material, but also strongly dependent on indenter geometry. To minimize difficulties in the extraction of quantitative material mechanical property information from the force curve, indenter geometry must be controlled and characterized on the same scale as the indentation, i.e. on the nanometer scale. Diamond, the hardest naturally occurring material, is an obvious choice as the indenter material. Conventional lapping techniques4 do not provide sufficient control to produce indenter geometries of the shapes and to the precision required for optimal nanoindentation measurements.

This work employed scanning probe microscopy (SPM) to study mass transport in the liquid-like layer (LLL) ice surfaces. Rapid healing of the damaged ice surface that took place only in the presence of the LLL was recently observed. This indicates that the LLL is responsible for the surface healing. Simple modeling shows that the healing rate is proportional to the LLL thickness cubed and inversely proportional to the film's viscosity. Thus an experimental study of the healing can provide valuable information on the physical parameters of the LLL.

Pure distilled deionized water, with a specific resistivity of 18.1 MΩ•cm, was used to grow ice crystals. The crystal surface was then prepared for scanning force microscopy (SFM) by either flattening using a microtome machine or flattening with the microtome machine and polishing gently using optically smooth clean quartz plates.

The AFM is a natural tool for exploring liquid-solid interfaces, but oscillating probe methods are limited by the viscous action of the liquid on the probe. If the probe is driven acoustically, high driving amplitudes are required to obtain a response from the probe, and this can give rise to spurious responses. The problem is solved if the probe is driven directly, using a magnetic film on the tip and a solenoid to provide a driving field. This method, Magnetic A/C mode (MacMode) has provided the highest resolution in both images of biomolecules and in force spectroscopy at the liquid-solid interface.

The interaction force is reduced because the microscope can be operated at low amplitudes of oscillation (0.5 to 5nm) with small changes (0.1 to 0.5nm) in amplitude used for sensing. This often results in greatly improved resolution, presumably because small aperities on the tip are not damaged.

To improve the understanding of the mechanical deformation mechanisms associated with friction, wear, and precision machining processes, a detailed set of microploughing experiments were performed on gold single crystal surfaces. Large single crystals that had an edge length of 1.5 mm and a thickness of 1 mm were used for this work. Since the microplough depths ranged from 100 nm to 1600 nm, it was important that the material be damage free at the surface. This condition was verified by alpha particle backscattering. A stand-alone STM head, having a singlecrystal diamond tip, was used in conjunction with a Digital Instruments Nanoscope Ilia controller to generate the 13 μm long microploughs. The vertical ploughing force was measured using a Mettler AE130 semi-microbalance.

After generating the microploughs and measuring their geometry with an AFM, some of the microploughs were cross sectioned for TEM observation.

The AFM technique has made a remarkable progress recently. However, relatively few studies using the UHV-AFM have been reported compared to those using atmospheric AFMs or UHV-STMs. Atomic-resolution images of the clean sample surface in ultrahigh vacuum, which is relatively active and not observable in atmosphere, have been reported only few examples. The intense reaction between the tip of the cantilever and the sample in contact mode imaging, one of the techniques used in atomic imaging in atmosphere, often damages the surface of the sample, making it difficult to acquire atomic-resolution images in UHV.

In order to reduce the strong interaction between the tip and the sample, the noncontact imaging technique for the UHV-AFM (NC-AFM: JAFM-4500XT) has been developed. However, none of the atmospheric NC-AFMs has succeeded in achieving atomic level resolution.

Scanning Probe Microscopy (SPM) is being developed as a possible solution to the problems inherent with analyzing the nanometer scale electronic properties of ULSI integrated circuits. Scanning Kelvin Probe Microscopy (SKPM) and Scanning Capacitance Microscopy (SCM) are both being developed to provide two dimensional dopant profiles of semiconductor devices. SKPM can also determine surface potentials, work functions, dielectric properties, and capacitance.

SKPM is based on the concept of Kelvin probe oscillating capacitor work function measurements. The small capacitance area of the SKPM tip and the high resistance of the system produce difficulties in monitoring and minimizing the current in the system. SKPM solves this problem by utilizing the force monitoring capability of the SPM to minimize the Kelvin force instead of the current. An AC voltage applied to the cantilever produces a DC force and AC forces at the AC frequency and the first harmonic of the AC frequency.

The surface morphology and electronic properties of a low energy boron implanted diamond films with shallow doping, prepared by microwave plasma enhanced chemical vapour deposition (CVD), have been characterised by atomic force microscopy (AFM), scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) techniques.

Both AFM and STM images taken at different locations on the films have exhibited similar morphological features on the (100) crystal surfaces. The crystal surfaces are not atomically flat but are composed of many hillocks as shown in Fig 1(a) to 1(c). The majority of values measured from the peaks of hillocks to the valleys are in the range of 2 to 5 nm, and the diameter of these hillocks is in the range of 50 to 250 nanometers. These crystal surface morphological features are believed to be caused in the high energy boron ion implantation process.

The atomic force microscope (AFM) has allowed microscopists to observe surface topography of non-conductive samples on the atomic level. One AFM mode that scanned probe microscopists have recently shown an interest in is the phase lag imaging mode. It has already been demonstrated that the resulting phase lag data can be used to identify different densities of microlayered polyethylene. However a quantitative understanding of phase lag imaging has yet to be fully developed. With a better understanding of the phase lag data it may be possible to estimate the modulus or other material properties of a sample from an AFM phase image alone.

The need for better understanding phase lag data is essential to increasing the knowledge of a how a material's microstructure behaves on the nanometer scale. This investigation focused on AFM phase lag data produced while scanning microstructures with large differences in modulus values between the compositional phases.

In many cases in experimental science, it is true that the instrument interface becomes a limiting factor in the efficacy of carrying out unusual experiments, or prevents the complete understanding of the acquired data. We are developing an advanced interface for Scanning Probe Microscopy (SPM) which allows intuitive rendering of datasets and natural instrument control, all in real-time. The interface, called the nanoManipulator, combines a high performance graphics engine for real-time data rendering with a haptic interface which places the human operator directly into the “feedback loop” that controls surface manipulations. In practice, the user holds a stylus in hand. By moving the stylus laterally, the user directs the movement of the SPM tip across the sample. The haptic interface enables the user to “feel” the surface by forcing the stylus to move up and down in response to the surface topography.

Background

The electron energy-loss spectrum of a single crystal diamond wedge has been examined, with particular reference to the excitation of plasmon oscillations in the bulk of a diamond crystal. The electron energy-loss spectrum has been previously studied [1], and in particular the ‘low-lo ss’ region of the spectrum shows a number of important features, Fig. 1. The main feature in the energy-loss spectrum is a peak at ∼ 33 eV which corresponds to a plasma resonance of valence electrons. Diamond has 4 valence electrons which yields a value of Ep = 31.0 eV. The upward shift in the resonance energy to 33 eV is caused by single-electron excitation at lower energy-loss values. An important feature is the “bump” at about 23 eV, which has been shown to be an interband transition [2].

Quantitative analysis of structural information provided by transmission electron diffraction and imaging strongly relies on computer simulations. An important quantity in dynamic calculation is the “absorption” potential. The absorption here actually means that the electron is not absorbed by the specimen rather it is scattered out of the elastic state (or Bragg peaks) due to energy-loss and momentum transfer, resulting in a decrease in the intensity of the elastic wave. This is the effect of inelastic scattering (or diffuse scattering) on the Bragg reflected waves [1]. Almost all of the model calculations for the absorption potential have been based on the approximation o riginally introduced by Y o sh ioka, in which the Green's function is approximated by its form in free-space. Thus, the absorption potential is simplified into a non-local function that depends only on the nature of the inelastic scattering.

The analysis of Selected Area Diffraction (SAD) patterns that are collected from a single phase material having sufficient crystallites to provide continuous rings is relatively straightforward. However, when this condition is not met and there may be several phases present having rings of a spotty nature, the pattern is complex and can be quite difficult to analyze manually because of the vast number of discrete spots. WinJade from MDI is an X-ray diffraction (XRD) analysis program with an Electron Diffraction Program Module (EDPM) that can be used to aid in the analysis of SAD patterns. The EDPM produces Integrated Circular Density Plots (ICDP), which are one-dimensional intensity profiles plotted as a function of equivalent XRD 20 values or crystal d-spacings. These ICDP's can be overlayed with XRD patterns or with reference lines from the NIST and JCPDS crystalline databases for direct comparisons.

As engineering properties are miniaturized by mo thinner films, crystallographic analyses become more appropriate by electron diffraction than XRD. Without synchrotron sources, XRD scans of such films often expose one peak at best. However, these thinner films become more suited for TEM, with less artifacts from sample preparation. XRD scans with peaks in the noise are quantitatively accepted, while vast differences in electron diffraction patterns remain unquantified. Digital recording of TEM information removes the uncertain hand waving of the darkroom; and fast, user-friendly computer processing especially removes the nonstatistical art in image analysis. This work inputs 16-bit (>65,000 gray levels) images of ring diffraction patterns into Digital Micrograph and utilizes a Rotation Average subroutine (1) to plot peak intensities.

Information storage in a hard drive utilizes sputtered thin films of HCP-Co-alloys with magnetic bits tied to the crystallographic orientation of each grain. Longitudinal-recording density and signal-to-noise can be enhanced for thin films with c-axes of all grains in plane.

Synchrotron Radiation has become an important tool for the analysis of silicon surfaces in both fundamental and applied problems with techniques ranging from x-ray scattering to fluorescence. Applications that have been studied include the analysis of ultra-low levels of impurities on silicon wafer surfaces using the total external x-ray fluorescence technique (TXRF), measurement of silicon wafer surface roughness using crystal truncation rod scattering, measurement of the stress and defects associated with isolation trenches used in the fabrication of integrated circuits, and the study of transient enhanced diffusion in implanted silicon using x-ray diffuse scattering.

As the dimensions of integrated circuits become smaller and smaller, the thickness of the gate oxide is being reduced to a level where it has become necessary to control the process to virtually atomic levels. With oxide thicknesses less than 100 Angstroms, surface impurities can have deleterious affects on the oxide properties.