Energy analysers hemispherical

Figure 2.3. Schematic diagram of a concentric hemispherical electron energy analyser.

Fig. 3. Cross-section of the combined UPS-XPS-LEED system described by Bradshaw and Menzel (25). A - Hemispherical electron energy analyser B - Slit-change mechanism C - Qua-drupole mass spectrometer D - Crystal manipulator E - LEED optics F - Assembly for electron bombardment of the sample replaceable by an argon ion gun G - Rare gas resonance lamp with axis perpendicular to the plane of the cross-section H - X-ray source. [Reproduced with permission from Ber. Bunsenges. 78, 1140 (1974)]...

Fig. 1. Schematic diagram of single-beam scattering spectrometer utilizing quadruple mass filters5 l.S.—ion source, G—grid, L,-L15—lens elements, R.C.— reaction chamber, C—channeltron multiplier, QMS—quadrupole mass filters, H—hemispherical energy analysers.

The measurement is carried out in an UHV chamber. Ultraviolet photons from a He lamp (21.2 or 40.8 eV) are shone at the sample to eject photoelectrons. The emitted electrons are collected by an electron energy analyser, such as a hemispherical mirror analyser, to produce a spectrum showing the number of electrons emitted with a given kinetic energy. Such spectra are representative of, although not identical to, the sample s valence band electronic density of states (DOS). 

Figure 13.9 Principle of electric- and magnetic-sector charged-particle analysers, here shown for a 180° sector (hemispherical analyser). Conceptually, electric sectors serve as kinetic energy analysers magnetic sectors (magnetic field perpendicular to the plane) constitute mass analysers...

The momentum microscope is a combination of a conventional PEEM column, which serves as an input to a double-hemispherical imaging electron energy analyser, shown schematically in Figure 8.8. The addition of the energy... 

The energy of the photoelectrons leaving the sample are determined using a Concentric Hemispherical Analyser (CHA), and this gives a spectrum with a series of peaks whose energy values are characteristic of each element. A schematic diagram of a CHA is shown in Figure 2.3. 

Figure 5. A horizontal schematic cut through the EMS spectrometer showing the monochromated and collimated incident beam and the hemispherical (fast) and toroidal (slow) energy and angle dispersive analysers as well as the retarding lens systems.

The retardation and deflection techniques represent the simplest methods of analysis using electrostatic fields. More sophisticated methods of electrostatic analysis are, of course, available and both cylindrical and hemispherical electrostatic analysers have been used to measure translational energies of ions formed by decomposition within ion sources [633, 667, 789, 790]. A Wien filter has been similarly employed [163]. 

Fig. 2.9. Schematic view of the coincidence spectrometer of Storer et al (1994) showing the hemispherical and toroidal energy and azimuthal angle analysers.

Many types of electron energy filter or analyser exist. Perhaps the commonest is the hemispherical condenser although a commonly used commercial instrument is based upon the 127° cylindrical condenser. ... 

Figure 8 Schematic illustration of a retarding-field analyser. Electrons transmitted through the probe hole are focused at the centre of a shielded hemispherical collector by the lens. The bias potential Vb is varied to obtain the energy spectrum of collected electrons...

Semi quantitative analyses of the calcium phosphate deposits were acquired using a Kratos Axis ULTRA XPS spectrometer incorporating a 165-mm hemispherical electron energy analyzer. The source of X-ray incident radiation was a monochromatic Al Ka (1486.6 eV) at 150 W (15 kV, 10 mA). Survey (wide) scans were taken at an analyzer pass energy of 160 eV. 

ICP analyses were performed by Plasma Absorption Emission Spectroscopy (ICP-AES). BET surface areas were measured with a Micromeritics TriStar 3000 instrument after degassing the samples at 150 C under a 0.13 Pa vacuum overnight. XPS analyses were performed on a SSI X-probe spectrometer (SSX-100/206 photoelectron spectrometer Fisons) equipped with a monochromatized microfocused Al Ka X-ray source (1486.6 eV) and a hemispherical analyser. The binding energies were calculated relative to the C-(C, H) component of the adventitious Cls carbon peak fixed at 284.8 eV. Zeta potential measurements were carried out in a PENKEM Zeta Meter 500, using 25 mg of sample ultrasonically dispersed in 200 ml of an aqueous solution... 

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