BSE

Application High-resolution signal (TEM, STEM) Back-scattering of electrons (BSE signal in SEM) Analytical signal (TEM, STEM, SEM) Emission of secondary electrons (SE signal in SEM)... 

One further breaks down the secondary electron contributions into three groups SEI, SEII and SEIII. SEIs result from the interaction of the incident beam with the sample at the point of entry. SEIIs are produced by BSE s on exiting the sample. SEIIIs are produced by BSEs which have exited the surface of the sample and further interact with components on the interior of the SEM usually not related to the sample. SEIIs and SEIIIs come from regions far outside that defined by the incident probe and can cause serious degradation of the resolution of the image. 

It is usual to define the primary beam current the BSE current /rse, the SE current and the sample current transmitted through the specimen to ground such that the Kirchoff current law holds ... 

Atomic number contrast can be used to estimate concentrations in binary alloys because the actual BSE signal increases somewhat predictably with the concentration of the heavier element of the pair. 

A significant fraction—about 15% for aluminum, 30% for copper, and 50% for gold—of the beam electron trajectories intersect the surface and escape as backscat-tered electrons (BSEs), as shown in Figure 2a. The majority of BSEs escape with more than half of their incident energy. Clearly, if these electrons had remained in... 

Centers for Disease Control and Prevention and National Institutes of Health. Primary Containment of Biohazards Selection, Installation and Use of Biological Safety Cabinets. Washington, DC U.S. Department of Health and Human Services, 1995 (available on http // wwxv.nichs.nih.gov/odhsb/biosafe/bse/bse.htm). 

In eq. (1) the ETT order parameter z = s(p-Pc) measures, in a convenient direction, the chemical potential from that corresponding to the ETT. From the values given in Table I for the above s and q, we readily see that the occurrence of the ETTs discussed in this paper always implies an increase of the alloy free energy. Thus, CuPt random alloys, that just below and above the equiatomic concentration present both the relevant ETT s, are less stable than CuPd or AgPd and, thus more likely to be destabilised. Moreover, the proximity to both the critical concentrations implies large contributions to the BSE from the X and L points. Now, the concentration wave susceptibility, Xcc(q). as observed by Gyorffy and Stocks, is proportional to... 

There has been great concern over the large-scale outbreak of BSE that occurred in the UK from 1988 as a result of feeding cattle with supplements prepared fiom sheep and cattle offal. Brain extracts firm BSE cattle have transmitted the disease to mice, sheep, cattle, pigs and monkeys. Studies of 12 recent cases of atypical CJD in the UK have provided evidence that the bovine prions have infected humans through the consumption of contaminated beef... 

Figure 9.12 Schematic diagram illustrating the geometry of detectors used for STEM BF, STEM HAADF and STM BSE imaging. (Reproduced from Ref. 35).

Figure 9.13 (a) SEM BSE image and (b) STEM HAADF image of Pd nanoparticles on a carbon support. The clarity of the images illustrates the advantage of the HAADF and BSE approach. (Reproduced from Ref. 36). 

BSE Age greater than or equal to 20 risk/benefit discussion All ages NR... 

BSE, breast self-examination CBE, clinical breast examination NR, not recommended , insufficient data to recommend for or against. 

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