Depth profiling detection limits

Site symmetry Depth Probed Depth profiling Detection limits Lateral resolution Imaging/mapping... 

Sputtered Neutral Mass noble gases ionized by atoms (or deeper depth profile detection limit ppm ... 

SNMS Spulleied Neutral Mass Spectroscopy Surface, bulk Plasma discharge noble gases 0.5-20 keV Sputtered atoms ioni by atoms or electrons then mass analyzed 0.1-0.5 nm (or deeper ion milling) 1 cm Elemental analysis Z > 3 depth profile detection limit ppm 4,6... 

Information Element range Destructive Lateral resolution Depth profiling Depth probed Detection limits Quantitative Imaging... 

The most common application of dynamic SIMS is depth profiling elemental dopants and contaminants in materials at trace levels in areas as small as 10 pm in diameter. SIMS provides little or no chemical or molecular information because of the violent sputtering process. SIMS provides a measurement of the elemental impurity as a function of depth with detection limits in the ppm—ppt range. Quantification requires the use of standards and is complicated by changes in the chemistry of the sample in surface and interface regions (matrix efiects). Therefore, SIMS is almost never used to quantitadvely analyze materials for which standards have not been carefiilly prepared. The depth resoludon of SIMS is typically between 20 A and 300 A, and depends upon the analytical conditions and the sample type. SIMS is also used to measure bulk impurities (no depth resoludon) in a variety of materials with detection limits in the ppb-ppt range. 

Detection limits Depth probed Depth profiling... 

Quantification Detection limits Depth profiling Penetration depth Depth resolution Lateral resolution... 

In summary, CL can provide contactless and nondestructive analysis of a wide range of electronic properties of a variety of luminescent materials. Spatial resolution of less than 1 pm in the CL-SEM mode and detection limits of impurity concentrations down to 10 at/cm can be attained. CL depth profiling can be performed by varying the range of electron penetration that depends on the electron-beam energy the excitation depth can be varied from about 10 nm to several pm for electron-beam energies ranging between about 1 keV and 40 keV. 

Today dynamic SIMS is a standard technique for measurement of trace elements in semiconductors, high performance materials, coatings, and minerals. The main advantages of the method are excellent sensitivity (detection limit below 1 pmol mol ) for all elements, the isotopic sensitivity, the inherent possibility of measuring depth profiles, and the capability of fast direct imaging and 3D species distribution. 

Measurement of depth profiles is based on detection of the masses of interest during sputter removal of the sample material. Such experiments have several limitations ... 

CPAA may be employed to determine trace element concentrations in bulk solid material, but its importance in our present context is that it permits the characterization of a thin surface layer, i.e. the mass of the analyte element per surface unit, with a good detection limit and outstanding accuracy. For example the composition of a surface layer (or foil) of known thickness can be determined, or, conversely, the thickness of a surface layer of known concentration. Depth profiling or scanning is not possible, and a disadvantage of the method is that heating occurs during irradiation. It is also not possible to discriminate between different oxidation states of the analyte element or between different compounds. 

Profiles in the Japanese Sea are similar for model and observational data. Concentration decreases down to 1000 m and remains constant below. Surface concentrations are lower for modeled profiles, most likely due to the emission scenario, that assumes identical temporal behaviour for all source points and does not capture all emitted mass. Due to the limited horizontal resolution of models, the topography of the ocean differs from the real one. In the Southern ocean concentrations were low throughout all depths, and for the measurements often below the detection limit of 6 pg/L. 

The principal advantage of the ion microprobe (as opposed to the Auger microprobe) is the ability to obtain depth profiles for trace elemental species present in the analytical volume. The characterization of coal fly ash clearly illustrates this point (11-14). Auger detection limits are comparable to BSCA, and thus only elements with bulk concentrations greater than 1% by weight in fly ash (Si, Al, Fe, Ca, S, Na, K) can be... 

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