Surface microanalytical

Surface Microanalytical Techniques for the Chemical Characterization of Atmospheric Particulates... 

Linton, R. W., Physico-Chemical Characterization of Environmental Particles Using Surface Microanalytical Techniques , Ph.D. Thesis, University of Illinois, Urbana, Illinois, 1977. 

SIMS is one of the most powerful surface and microanalytical techniques for materials characterization. It is primarily used in the analysis of semiconductors, as well as for metallurgical, and geological materials. The advent of a growing number of standards for SIMS has gready enhanced the quantitative accuracy and reliability of the technique in these areas. Future development is expected in the area of small spot analysis, implementation of post-sputtering ionization to SIMS (see the articles on SALI and SNMS), and newer areas of application, such as ceramics, polymers, and biological and pharmaceutical materials. 

This volume contains 50 articles describing analytical techniques for the characterization of solid materials, with emphasis on surfaces, interfaces, thin films, and microanalytical approaches. It is part of the Materials Characterization Series, copublished by Butterworth-Heinemann and Manning. This volume can serve as a stand-alone reference as well as a companion to the other volumes in the Series which deal with individual materials classes. Though authored by professional characterization experts the articles are written to be easily accessible to the materials user, the process engineer, the manager, the student—in short to all those who are not (and probably don t intend to be) experts but who need to understand the potential applications of the techniques to materials problems. Too often, technique descriptions are written for the technique specialist. 

The latest innovation is the introduction of ultra-thin silica layers. These layers are only 10 xm thick (compared to 200-250 pm in conventional plates) and are not based on granular adsorbents but consist of monolithic silica. Ultra-thin layer chromatography (UTLC) plates offer a unique combination of short migration distances, fast development times and extremely low solvent consumption. The absence of silica particles allows UTLC silica gel layers to be manufactured without any sort of binders, that are normally needed to stabilise silica particles at the glass support surface. UTLC plates will significantly reduce analysis time, solvent consumption and increase sensitivity in both qualitative and quantitative applications (Table 4.35). Miniaturised planar chromatography will rival other microanalytical techniques. 

This technique is simple in basic principle. Material is first rapidly frozen to the temperature of liquid nitrogen. It is then fractured, cryo-planed to produce a flat surface for analysis, and transferred to the cryo-stage of an SEM. It is analyzed while still frozen, and thus ion movement during tissue preparation should be minimal. A more detailed scheme of a typical procedure (45,46) is given in Subheading 3.4.2.1. This is undoubtedly the most popular microanalytical method with plant scientists at present, and as Table 1 shows it has been applied to a wide range of tissues and research topics (46-53). Recent developments include a... 

Several other microanalytical methods in common use potentially have application on soil and sediments section samples. Laser-ablation inductively coupled plasma mass spectrometery (LA-ICP-MS) has been used on soil thin-sections from a controlled field experiment (21) but required special resins in the preparation. There is presently (May 2006) no reported use of this method on archaeological soil samples. Likewise, for extremely fine-resolution studies (i.e. <10 pm) with low minimum detection limits and despite difficult calibration, secondary ion microscopy (SIMS) has a potential role in examining archaeological soil thin sections. At even higher lateral resolutions ( 100 nm) Auger electron spectroscopy (AES) could also be considered for surface (<5 nm deep) analyses. At present however, the use of these methods in soil systems is limited. SIMS has been focused on biochemical applications (22), whereas AES... 

A representative collection of surface chemical data of several carbon blacks is compiled in Table 5 which was collected from extensive data [33]. The specific surface area varies by an order of magnitude for the five samples. The total content of heteroatoms (determined by classical microanalytical techniques) amounts to between about 1 and 5wt% which is a sizeable quantity for a material which is nominally pure carbon. 

Microanalytical methods are used to move further down in the characterization scale. X-ray photoelectron spectroscopy (XPS or ESCA), (see Barr) Auger electron spectroscopy (AES), and secondary ion mass spectroscopy (SIMS) as presented by Leta for imaging FCC catalysts, are surface analysis techniques providing chemical analy-... 

These techniques fall into two categories those considered as routine (e.g. atomic absorption and emission spectroscopy, X-ray fluorescence) and a growing number of microanalytical surface techniques (e.g. laser microprobe mass analysis [LAMMA] and sensitive high-resolution ion microprobe [SHRIMP]). Each analytical technique requires specific sample preparation prior to analysis, as summarised in Table 13.1. 

X-ray photoelectron spectroscopic (XPS) studies were conducted using a Surface Science Laboratories X-ray photoelectron spectrometer. Wavelength-dispersive electron microprobe results were obtained by Mr. John Donovan at the Department of Geology microanalytical facility at UC Berkeley. 

The chemistry of single flnid inclnsions can be determined with certain microanalytical chemical techniqnes. The chemistry of flnid inclusions can be used to document the types of waters at the Earth s surface in the past and to interpret what controlled the chemistry of those waters through time. To date, little attention has been given to chemical analysis of fluid inclusions in lacustrine minerals. However, given the great developments in the last ten years in chemical analysis of individual fluid inclusions, the following techniques could be applied to some lacustrine minerals. 

The basic measuring strategy of microscopic X-ray fluorescence analysis (g-XRF) is illustrated in Fig. 11.23. This microanalytical variant of bulk EDXRF is based on the localized excitation and analysis of a microscopically small area on the surface of a larger sample, providing information on the lateral distribution of major, minor and trace elements in the material under study. Essentially, a beam of primary X-rays with (microscopically) small cross-section irradiates the sample and in-... 

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