Electron Beam Energy

In principle, fast electrons are generated in a high vacuum (typically 10 torr) by a heated cathode. The electrons emitted from the cathode are then accelerated in an electrostatic field applied between cathode and anode. The acceleration takes place from the cathode that is on a negative high-voltage potential to the grounded vessel as anode. The accelerated electrons may sometimes be focused by an optical system to the window plane of the accelerator.  

Source Emission Generated By Main Emission Wavelengths, nm UV Radiant Power, W/cm Main Applications Note 

Low-pressure mercury lamp Low-pressure glow discharge 254 and 185 O.l-l.O Liquid crystal displays, photoresist technology Weaker emission lines at 313 and 578 nm 

Excimer lamp Dielectric barrier (silent) discharge 172,222, 308 1-10 UV curing. Major R D 

When an electron beam enters a material (this includes the accelerator exit window, the air gap, and the material being irradiated), the energy of the accelerated electrons is greatly altered. They lose their energy and slow down almost continuously as a result of a large number of interactions each with only small energy loss. 

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

Instmmentation for tern is somewhat similar to that for sem however, because of the need to keep the sample surface as clean as possible throughout the analysis to avoid imaging surface contamination as opposed to the sample surface itself, ultrahigh vacuum conditions (ca 10 -10 Pa) are needed in the sample area of the microscope. Electron sources in tern are similar to those used in sem, although primary electron beam energies needed for effective tern are higher, typically on the order of ca 100 keV. 

Yes, by varying the range of electron penetration (between about 10 nm and several im), which depends on the electron-beam energy (1-40 keV). 

Since the excitation depth can be selected by varying the electron-beam energy, depth-resolved information can be obtained. 

Nonradiative surface recombination is a loss mechanism of great importance for some materials (e.g., GaAs). This effect, however, can be minimized by increasing the electron-beam energy in order to produce a greater electron penetration range. 

In summary, CL can provide contactless and nondestructive analysis of a wide range of electronic properties of a variety of luminescent materials. Spatial resolution of less than 1 pm in the CL-SEM mode and detection limits of impurity concentrations down to 10 at/cm can be attained. CL depth profiling can be performed by varying the range of electron penetration that depends on the electron-beam energy the excitation depth can be varied from about 10 nm to several pm for electron-beam energies ranging between about 1 keV and 40 keV. 

Applications of CL to the analysis of electron beam-sensitive materials and to depth-resolved analysis of metal-semiconductor interfaces by using low electron-beam energies (on the order of 1 keV) will be extended to other materials and structures. 

Surface atomic structure. The integrated intensity of several diffracted beams is measured as a fimction of electron beam energy for different angles of incidence. The measurements are fitted with a model calculation that includes multiple scattering. The atomic coordinates of the surfiice atoms are extracted. (See also the article on EXAFS.)... 

Fig. 1. Electron beam penetration in various materials as a function of electron beam energy.

Sodium valproate was not sufficiently volatile for mass spectral analysis. The mass spectrum of valproic acid as shown in Figure 5 was obtained using an Associated Electrical Industries Model MS-902 Mass Spectrometer with the ionization electron beam energy at 70 eV. High resolution data were compiled and tabulated with the aid of an on-line PDP-11 Computer. 

Electron beam (EB) disinfection, 8 661-662 Electron beam energy, ink curing via, 14 314... 

The mass spectral data of Nier and Hanson show that the value of x is insensitive to changes in electron beam energy over the range 25-400 eV, and that it lies between 0.17 and 0.19, depending on the fraction of charge-transfer reactions of HX2+ and X2+ which result in dissociation. In view of the uncertainty in the relative abundance of H+, the value of x may be taken as 0.20 + 0.02. Similarly, the value of x for HBr is 0.40 0.04. 

X-ray Absorption Spectra (XAS). X-ray absorption measurements were performed at station 9.2 of the SRS at Daresbury (UK) with an electron beam energy of 2 GeV and a stored current varying between 290 and 160 mA. The wiggler was operational at 5.0 Tesla. Data were collected in the transmission mode from 11.37 keV to 13.43 keV (Pt Li -edge 11.564 keV, Pt Vedge 13.273 keV) with a Si (220) monochromator detuned to 50 % of the maximum intensity... 

Mass spectra (El) are routinely obtained at an electron beam energy of 70 eV. The simplest event that occurs is the removal of a single electron from the molecule in the gas phase by an electron of the electron beam to form the molecular ion, which is a radical cation (M +). For example, methanol forms a molecular ion in which the single dot represents the remaining odd electron ... 

Fluorinated polyimide (PMDA/TFDB) and nonfluorinated polyimide (PMDA/DMDB) films prepared on a silicone substrate were introduced into an electron beam lithography system and subsequently exposed for square patterns (4x4 mm). The electron beam energy was 25 keV the beam current was 10 nA, and the beam dose was 300-1500 pC/cm. The 4x4 mm square was written by a 0.1-pm-wide electron beam. 

Fig. 9. Typical diffraction patterns from the (111) face of a platinum single crystal at four different incident electron beam energies (a) 51 eV, (b) 63.5 eV. (c) 160 eV, and (d) 181 eV.

Fig. 2.1 HREEL spectra of C60 multilayer films shown as a function of increasing hydrogen exposure. The primary electron beam energy is 6 eV and the sample temperature is -150°C. (a) no hydrogen exposure, FWHM = 36.5 cm-1 (b) a 45 L hydrogen exposure, FWHM = 34.8 cm-1 (c) a 180 L hydrogen exposure, FWHM = 40.4 cm-1 and (d) a 1,000 L hydrogen exposure, FWHM = 60.4 cm-1. Spectral features labeled for comparison with Table 2.1 (Reproduced by permission of the AAS from Stoldt et al. 2001).

The mass spectra of atenolol and compound were obtained by direct insertion of the sample into CEC 21-Ho B mass spectrometer. Characteristics of these mass spectra are summarized in Tables 5. and 6, and Pig. 5 The ion source temperature was 15o°C and 2oo-25o°C, respectively, and the ionizing electron beam energy was 7o eV. 

Wurtz-synthesized PMPS was selected as the material to be studied when subjected to cathodoluminescence (CL).98 The CL method of the study of PMPS is based on the measurement of CL intensity of emitted light after its passage through the specimen, as shown in Figure 20. For the PMPS degradation measurements, electron beam energy of 10k eV was used. The PL emission spectrum consists of two emission bands. The maximum of the... 

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