Electron Microscopy in Lung Research
Joan Gil in Models of Lung Disease, 2020
In the SEM, the electrons are focused on the surface of the specimen and scanned across it. As they are deflected over the surface of the specimen, atoms near the point where the electrons enter the specimen are excited by the absorbed energy. As they decay back to ground state, they give off the absorbed energy by emitting secondary electrons, x-rays, or photons of light (cathodoluminescence) (Fig. 2). These secondary emissions all contain potential information about the specimen. In addition, some of the incident electrons are elastically scattered as a result of interactions with atomic nuclei in the specimen, and these electrons also contain information about the specimen. Ordinarily the secondary electrons are used to generate an image. The other types of emission are used for special applications, particularly analytical microscopy.
Patterned Sapphire and Chip Separation Technique in InGaN-Based LEDs
Iniewski Krzysztof in Integrated Microsystems, 2017
Figure 23.4a shows the cross-sectional transmission electron microscope (TEM) images under g = 0002 two-beam condition of the interface region between the CSPSS and a GaN layer grown on it, demonstrating that the ELOG-like mode on the CSPSS effectively suppresses the propagation of dislocation into the cone region, even though many dislocations were observed in the film grown on the basal plane of the sapphire. This reduction of dislocation was also confirmed by performing a cathodoluminescence (CL) measurement at room temperature as shown in Figures 23.4b and c. In bright regions, a radiative process dominates over a nonradiative process because of the lower density of structural defects. The dark spot density in the film grown on a CSS is roughly estimated to be about 7 × 108 cm−2. Apparently, the dark spot density in the film grown on a CSPSS was decreased to about 2 × 108 cm−2 in number.
Optical-CT Imaging
George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos in Handbook of Small Animal Imaging, 2018
POT is a passive imaging technique in which biological cells labeled with optical probes emit fluorescent light in case of an external excitation source. Fluorescence described here is the emission of light from a material that has been excited by an external excitation source; examples include photoluminescence excited by a light beam such as fluorescence and cathodoluminescence excited by an electron beam such as in x-ray luminescence (XRL) in living organisms and animals. There are two typical categories of POT presented in this section: FMT and XRLT (Wu et al. 1997; Ntziachristos et al. 2004; Pratx et al. 2010b; Cong et al. 2011).
Diagnostic Electron Microscopy of Retina
Published in Seminars in Ophthalmology, 2018
Rishikesh Kumar Gupta, Inderjeet Kaur, Tapas C. Nag, Jay Chhablani
Once the coherent beam of electrons interacts with the sample, some of the electrons reflect back (called backscattered electrons). Some electrons deliver their energy to the sample’s molecules and excite the outer surface electrons of the samples. These excited electrons get emitted, are known as the secondary electrons. Other types of electrons are X-rays, cathodoluminescence, and Auger electrons as shown in Figure 1. The specialized detector can detect all these different kinds of electrons, produce the images of the sample as illustrated in Figure 1, called SEM.29 SEM helps in the study of the surface properties of the sample. Apart from these, few electrons do not lose any energy while interacting with the sample due to elastic scattering, and few others lose the minimal amount of energy, called inelastic scattering. Also, very few electrons get transmitted without any scattering, called as unscattered electrons. These three types of transmitted electrons fall on the fluorescent screen and produce the quantitative images of the sample as shown in Figure 1, called TEM.28
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