Sensitivity, analytical image

CARS microscopy has emerged as a highly sensitive analytical tool for vibrational bioimaging, predominantly, of lipids in membrane model systems [69, 81-84], live unstained cells [85-95, 43], and both ex vivo and in vivo tissues [26, 96-103, 43]. Examples of CARS imaging applications in the physical and material sciences include the study of fracture dynamics in drying silica nanoparticle suspensions [104], patterned polymeric photoresist film [105], drug molecules in a polymer matrix [106], and liquid crystals [107, 108],... 

Analytical Considerations with Image Devices. In considering the role of image devices in SMA, one should not lose sight of the analytical constraints involved. For example, typical analytical samples contain elements present at major-, minor-, and trace levels. In most cases it will not be possible to dilute the sample extensively and still determine the trace elements. As a result, the analytical lines employed in the determination should be selected with the expected concentrations of the elements in mind. Thus less sensitive analytical lines (such as nonresonance lines if the sample is analyzed by atomic emission) should be chosen for the determination of major- or minor elements, whereas the most sensitive resonance lines will need to be used for the determination of trace elements. Even though the same set of... 

ToF-SIMS is a siirface-sensitive analytical method that uses a pulsed ion beam to remove molecules from the very outermost surface of the sample. The secondary ions are removed from the uppermost monolayers on the surface and then accelerated into a flight tube their mass is determined by measuring the exact time at which they reach the detector. Three operational modes are available when using ToF-SIMS, namely surface spectrometry, surface imaging, and depth profiling. 

In contrast to many other surface analytical techniques, like e. g. scanning electron microscopy, AFM does not require vacuum. Therefore, it can be operated under ambient conditions which enables direct observation of processes at solid-gas and solid-liquid interfaces. The latter can be accomplished by means of a liquid cell which is schematically shown in Fig. 5.6. The cell is formed by the sample at the bottom, a glass cover - holding the cantilever - at the top, and a silicone o-ring seal between. Studies with such a liquid cell can also be performed under potential control which opens up valuable opportunities for electrochemistry [5.11, 5.12]. Moreover, imaging under liquids opens up the possibility to protect sensitive surfaces by in-situ preparation and imaging under an inert fluid [5.13]. 

Apart from the sampling principle, sensor layouts can also be subdivided into point-probe sensors, giving averaged information about the analytes within the sensitive field, and imaging sensors, delivering a spatially as well as spectrally resolved image of the investigated area. 

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