LVSEM

LVSEM low-voltage scanning electron microscope MTF modulation transfer function... 

Cambridge Instruments builds the first commercial SEM 1968 Crewe and colleagues introduce the PEG as electron beam source 1968 Crewe and colleagues build the first STEM prototype 1995 Zach proves the concept of a corrected LVSEM... 

Modem EMs use electromagnetic lenses, shift devices and spectrometers. However, electrostatic devices have always been used as electron beam accelerators and are increasingly being used for other tasks, e.g. as the objective lens (LVSEM, [10]). 

The first corrected electron-optical SEM was developed by Zach [10]. Eor low-voltage SEM (LVSEM, down to 500 eV electron energy instead of the conventional energies of up to 30 keV) the spot size is extremely large without aberration correction. Combining and correction and a electrostatic objective lens, Zach showed that a substantial improvement in spot size and resolution is possible. The achievable resolution in a LVSEM is now of the order of 1-2 mn. More recently, Krivanek and colleagues succeeded in building a corrected STEM [53,M]. 

Pawley, J., and Albrecht, R. (1988) Imaging colloidal gold labels in LVSEM. Scan. Microsc. 10, 184-189. 

Recent advances in ultra high-resolution low-voltage FE SEM (HR-LVSEM) and extreme FESEM in catalysis... 

Figure 2.13. Pd/C nanocatalyst in (a) BSE and (b) HAADF STEM in the same LVSEM instrument. For real-life catalysts on uneven (irregular) supports, BSE appears to be an effective method.

Figure 2.14. (a) LVSEM of Pt catalyst particle (arrowed) (b) EDX in LVSEM showing the Pt. (The particle site is 0.1 micron, after Boyes 1994.)... 

Figure 5.16. In situ LVSEM image of (a) the as-deposited Ag/alumina catalyst and (b) when it is dynamically heated at 200 °C.

Figure 5.27. Nanocatalysts of Ru/Ti02 (a) HR LVSEM image iUustrating the uniform distribution of Ru (arrowed) on the support surface (b) atomic structure of Ru/Ti02 in atomic-resolution ETEM at room temperature. The Ru is in single-crystal clusters in (001) (Ru is hexagonal a = 0.27 nm, c = 0.428 nm) and titania exhibits primarily (010) and (110). (After Gai et al 2000.)...

High-Resolution AFM (and LVSEM) Studies of Starch Granule Surface Structure... 

Figure 5.18 (a) LVSEM micrograph of a typical potato starch granule surface region (magnification... 

X, scale bar represents 3 pm) (b) LVSEM micrograph of a typical region of a Riband wheat starch granule surface. (Magnification 10000X, scale bar represents 3pm)... 

While the use of a separate LVSEM instrument to ensure sampling representivity provides high-resolution imaging of uncoated samples, various other approaches also exist. For example, there are now scanning probe microscopes located within... 

The LVSEM was performed with a microscope Quanta 200 FEG (FEI, Czech Republic). Neat hydrated hydrogels were cut with a razor blade into 5 mm cubes, flash frozen in hquid nitrogen and placed on the sample stage cooled to -10°C. Before... 

The prepared PHEMA constructs had always an opaque appearance indicating a permanent porous stracture. Pores are generally divided into micro-, meso-, macropores, and small and large superpores. Morphology of water-swollen PHEMA hydrogels was investigated by LVSEM as shown in Figrrre 1. 

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