Surface resolution

Using a visible light probe NSOM is the eadiest of the probe scopes, at least in conception, and is another apparent exception to the diffraction-liinited resolution rule, in that NSOM illuminates an object with a beam of visible light smaller than the diffraction limit. The resolution then is limited only by the size of that beam. To achieve this, light issuing from a very tiny aperture at the end of a glass capillary scans a very near sample. The tip must be located on the order of X/2 from that surface. Resolution in the range of 10—20 nm has been achieved (31). 

Determination of concentration profiles from the raw data can be more complicated when protons are used as the incident particles. The energy loss ( dE/ die) is smaller for protons and straggling effects are more important. The observed profile A (AJ)) is a convolution of the actual concentration profile C x with a depth resolution function (x, Eq), which broadens with increasing x roughly as Jx- Hence, resolution deteriorates with depth. However, near-surface resolution for resonant profiling may be on the order of tens of A. 

The application of interference techniques overcomes the limitations exerted by the large optical wavelengths. With commercial phase-measurement interference microscopes (PMIM), a surface resolution of the order of 0.6 nm can be achieved [33, 34]. In a microscope a laser beam is both reflected from the sample surface and from a semitransparent smooth reference surface (Fig. 3). The interference pattern is recorded on an area detector and modulated via the piezo-electric driven reference surface. The modulated interference pattern is fed into a computer to generate a two-dimensional phase map which is converted into a height level contour map of the sample surface. While the lateral resolution (typically of the... 

Selection of columns and mobile phases is determined after consideration of the chemistry of the analytes. In HPLC, the mobile phase is a liquid, while the stationary phase can be a solid or a liquid immobilised on a solid. A stationary phase may have chemical functional groups or compounds physically or chemically bonded to its surface. Resolution and efficiency of HPLC are closely associated with the active surface area of the materials used as stationary phase. Generally, the efficiency of a column increases with decreasing particle size, but back-pressure and mobile phase viscosity increase simultaneously. Selection of the stationary phase material is generally not difficult when the retention mechanism of the intended separation is understood. The fundamental behaviour of stationary phase materials is related to their solubility-interaction... 

Tapping Mode AFM measures contours by tapping the surface with an oscillating probe tip thereby minimizing shear forces that may damage soft surfaces. This allows increased surface resolution. This is currently the most widely employed AFM mode. 

The methods of remote sounding of C02 fluxes are mainly based on NDVI measurements (Burgheimer et al., 2006 Myeong et al., 2006) using various satellite technologies as well as in situ measurements with SCIAMACHY carried by satellites of the ESA series. The surface resolution of SCIAMACHY constitutes 320 km, and the frequency of measurements is 36 hours. 

Electron microprobes permit chemical microanalysis as well as SEM and BSE detection, often referred to as analytical electron microscopy (AEM), or electron probe microanalysis (EPMA)56 57. This is because another product of the surface interaction with an incident electron beam is X-ray photons which have wavelengths and energies dependent on element identity and on the electron shell causing the emission. Analysis of these photons can give a local chemical analysis of the surface. Resolution of 1 pm is attainable. Two types of X-ray spectrometer can be employed ... 

Hassett, D. M., Marsden, C. J., and Smith, B. J., The ammonia dimer potential energy surface Resolution of the apparent discrepancy between theory and experiment , Chem. Phys. Lett. 183, 449-456 (1991). 

Farin, D., Volpert, A., and Avnir, D. 1985. Determination of adsorption conformation from surface resolution analysis. Journal of the American Chemical Society 107, 3368-3370. 

Thermal transfer printing is the selective heating (computer-controlled) and cooling of small elements in a print-head which can be used to impress a one-use thermal ribbon onto the substrate surface. Resolutions of up to 12 dots per mm can be achieved. 

EEED Eow Energy Electron Diffraction Surface Mono-energetic electron beam 10-1000 eV Diffracted electrons 0.4-2 nm <6 pm Crystallographic structure of surface resolution 0.01 nm 36... 

Technique Sample Conditions Surface, specificity Surface, resolution Time needed for analysis ... 

Information regarding the chemistry of the film with greater surface resolution can be... 

STM Sanning Tunneling Microscopy Polished or cleaved surface (conducting) Tunneling current contr sample and very sharp 1-6 nm 2-10 nm Alomic-scale relief map of surface resolution verl. 0.002 nm, hor. 0.2 nm 39... 

Radar has been used to obtain topographic profiles across the Moon and the inner planets. For example. Fig. 9 shows a three-dimensional reconstruction of topography derived from altimetric profiles obtained for Mars in the vicinity of the giant shield volcano Arsia Mons. The altimetric resolution of the profiles is about 150 m (1 /xsec in delay), but the surface resolution, or footprint, is very coarse ( 75 km). Figure 10 shows altitude profiles across impact basins on Mercury. The Magellan radar altimeter, with a footprint typically 20 km across and vertical resolution on the order of tens of meters, has produced detailed topographic maps of most of Venus. 

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