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.

Due primarily to the absence of Bremsstrahlung radiation, fluorescent spectra obtained with x-ray excitation of a sample have a lower background than those obtained with electron excitation. This can be used to detect elements in liquids at very low concentrations under certain conditions. The technique consists of placing a small measured volume of liquid to be analyzed for trace elements on a thin, low atomic number film; evaporating the liquid to dryness; placing it under an x-ray beam; and obtaining a fluorescent spectra. The residue from the evaporated liquid contains any trace elements present, which then produce characteristic peaks in the fluorescent spectrum. These peaks can be used to measure concentrations quantitatively.

This technique has been around for some time, but with detection limits at the parts per million (ppm) level. Although there are many definitions of detection limit, the most commonly used one is from Burton:

X-ray microscopy is a rapidly developing field stimulated by the development of brilliant X-ray sources and high resolution X-ray lenses. It provides higher resolution than optical microscopy and higher penetration power than electron microscopy. Therefore, X-ray microscopy allows high resolution imaging of thick hydrated samples. The two dominating processes determining the contrast in X-ray microscopy are photoelectric absorption and phase shift. For this reason X-ray microscopy can be performed in amplitude and phase contrast. The Göttingen X-ray microscope at the BESSY electron storage ring in Berlin is operating in both contrast modes and is used for different application fields, for example in biology, biophysics, medicine, colloid chemistry, and soil sciences.

Especially biological objects are sensitive to ionizing radiation. Theoretical investigations show that X-ray images of frozen-hydrated specimen can be obtained without radiation induced artifacts. Therefore, an object stage for cryogenic specimen was developed and implemented on the Gottingen transmission X-ray microscope (TXM) at the electron storage ring BESSY.

The Center for X-ray Optics (CXRO) built and operates a high-resolution soft x-ray microscope (XM-1) at the Advanced Light Source in Berkeley. We report on the use of this instrument in a variety of scientific fields, including biology, civil engineering and environmental sciences.

The microscope is a conventional (full field) x-ray microscope, which uses zone plate lenses to provide high resolution transmission images. The optical setup is similar to the Göttingen x-ray microscope, operated at the BESSY synchrotron radiation facility in Berlin, Germany. A condenser zone plate, fabricated by the Göttingen group, is illuminating the sample and an objective zone plate, fabricated by Erik Anderson (CXRO), is forming an enlarged image on an x-ray CCD camera. While the optical path of the microscope is in vacuum, the sample is at atmospheric pressure, flushed by helium. The spatial resolution of our microscope is 43 nm, measured as the distance from 10%-90% intensity in the image of a knife-edge.

With the steady improvement of x-ray optics with high resolution and efficiency, and continued development or adaptation of different imaging and measuring techniques, soft x-ray microscopy has emerged as a powerful method to image and analyze fully hydrated specimens of several micrometer thickness at sub-optical resolution (for a recent overview, see ref. 1). We report on experiments performed with the cryo scanning transmission x-ray microscope (cryo-STXM), which has recently come into operation at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory.

Cryo-STXM uses x-rays with energies between the absorption edge of Carbon (E = 284 eV) and Oxygen (E = 543 eV) from the soft x-ray undulator at the NSLS. Fully hydrated specimens such as eucaryotic cells in water or ice layers of up to 10 micrometer thickness can be imaged without any additional need for contrast enhancing techniques.

Ultra-thin unstained sections of femoral neck bone from normal and ovariectomised mice were imaged in a scanning transmission x-ray microscope. The images were formed using soft x-ray energies at the calcium L and carbon K edges. The aim of the study was to quantitatively map the calcium, protein and embedding medium in normal and ovariectomised (osteoporotic) mice to compare the quantity and distribution of mineral (via calcium), collagen (via protein) and hydrated content (via embedding medium substitution).

A set of seven images were taken of both the normal and ovariectomised mouse sections. These images were processed using x-ray optical constants to produce mass thickness maps. The thickness of the sections from the normal mouse and ovariectomised mice were 205nm and 375nm respectively. The images show embedding medium, protein and calcium maps of near complete sections of the majority of the femoral neck at equivalent neck positions in the normal (la, 2a & 3a) and ovariectomised (lb, 2b & 3b) mouse bone sections.

We discuss the scheme and test performances of the recently commissioned MEPHISTO system in its final configuration. The tests show that the improvements in the electron optics system with respect to other instruments in the same class made it possible to reach lateral resolutions in the 50 nm range. They also demonstrate rather good spectromicroscopy and spectroscopy performances, reliability and flexibility of operation.

This instrument belongs to the class of the electron-imaging systems, like the PEEM (PhotoElectron Emission Microscope) [1] and the X-PEEM (X-ray PhotoElectron Emission Microscope) Microscope [2-5], Our new instrument, called MEPHISTO from the French acronym “Microscope a Emission de Photo électrons par Illumination Synchrotronique de type Onduleur” (Photoelectron Emission Microscope by Synchrotron Undulator Illumination) shares the good characteristics of the instruments of its class: real-time chemical imaging, fast taking of local x-ray absorption spectra, high spatial resolution, large dynamic range, flexibility and user-friendliness.

The phase of a coherent wave is an intuitively well understood concept and efforts to measure the phase of a wave are a staple of visible, x-ray, electron and atom optics. However, in a subtle way, phase is often measured where it is not even defined. An example of this is adaptive optics where the atmospheric phase distortion of light from astronomical objects is measured using polychromatic light. The assumption buried under this work is that it is possible to sensibly talk about phase even though the context of the discussion does not permit phase to be defined according to elementary concepts.

We have been undertaking an ongoing program investigating the nature of wavefields and exploring their characterisation using more robust approaches than standard techniques such as interferometry In a very recent paper we have developed a new viewpoint on phase defined via the Poynting vector of the radiation and where the phase acts as a set of potentials leading to the Poynting vector field.