Electron emission energy

The Fokker Contamination Tester, described by Bijlmer (1978), uses an oscillating probe to measure the electron emission energy. This varies greatly with the degree of surface contamination, and can even be used to detect residues from alkaline cleaning operations. 

XES, Soft x-ray emission An x-ray or electron beam Energy levels and chemical... 

Figure Al.7.12. Secondary electron kinetic energy distribution, obtained by measuring the scadered electrons produced by bombardment of Al(lOO) with a 170 eV electron beam. The spectrum shows the elastic peak, loss features due to the excitation of plasmons, a signal due to the emission of Al LMM Auger electrons and the inelastic tail. The exact position of the cutoff at 0 eV depends on die surface work fimction.

If we require similar information regarding the ground state potential energy surface in a polyatomic molecule the electronic emission specttum may again provide valuable information SVLF spectroscopy is a particularly powerful technique for providing it. 

Edx is based on the emission of x-rays with energies characteristic of the atom from which they originate in Heu of secondary electron emission. Thus, this technique can be used to provide elemental information about the sample. In the sem, this process is stimulated by the incident primary beam of electrons. As will be discussed below, this process is also the basis of essentially the same technique but performed in an electron spectrometer. When carried out this way, the technique is known as electron microprobe analysis (ema). 

An alternative mechanism of excess energy release when electron relaxation occurs is through x-ray fluorescence. In fact, x-ray fluorescence favorably competes with Auger electron emission for atoms with large atomic numbers. Figure 16 shows a plot of the relative yields of these two processes as a function of atomic number for atoms with initial K level holes. The cross-over point between the two processes generally occurs at an atomic number of 30. Thus, aes has much greater sensitivity to low Z elements than x-ray fluorescence. 

Electron Microprobe A.na.Iysis, Electron microprobe analysis (ema) is a technique based on x-ray fluorescence from atoms in the near-surface region of a material stimulated by a focused beam of high energy electrons (7—9,30). Essentially, this method is based on electron-induced x-ray emission as opposed to x-ray-induced x-ray emission, which forms the basis of conventional x-ray fluorescence (xrf) spectroscopy (31). The microprobe form of this x-ray fluorescence spectroscopy was first developed by Castaing in 1951 (32), and today is a mature technique. Primary beam electrons with energies of 10—30 keV are used and sample the material to a depth on the order of 1 pm. X-rays from all elements with the exception of H, He, and Li can be detected. 

The incoming electron beam interacts with the sample to produce a number of signals that are subsequently detectable and useful for analysis. They are X-ray emission, which can be detected either by Energy Dispersive Spectroscopy, EDS, or by Wavelength Dispersive Spectroscopy, WDS visible or UV emission, which is known as Cathodoluminescence, CL and Auger Electron Emission, which is the basis of Auger Electron Spectroscopy discussed in Chapter 5. Finally, the incoming... 

Figure 3 First-derivative electron emission spectra from pure lanthanum taken with primary electron beams having energies of 250 and 235 eV showing the unshifted Auger peaks and the shifted REELS peaks.

Beta radiation Electron emission from unstable nuclei, 26,30,528 Binary molecular compound, 41-42,190 Binding energy Energy equivalent of the mass defect measure of nuclear stability, 522,523 Bismuth (m) sulfide, 540 Blassie, Michael, 629 Blind staggers, 574 Blister copper, 539 Blood alcohol concentrations, 43t Body-centered cubic cell (BCC) A cubic unit cell with an atom at each comer and one at the center, 246 Bohrmodd Model of the hydrogen atom... 

Figure 10-10. (a) Semilogarillnnic plol of ihc stimulated emission transients for various excitation pulse energies measured for LPPP on glass. The excitation pulses have a duration of 150 fs and are centered at 400 nm. The probe pulse were spectrally filtered (Ao=500nin, Aa=l0nm). (b) Emission spectra recorded for the same excitation conditions. The spectra are normalized at the purely electronic emission baud (according lo Ref. [181). 

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