Emission angle

This equation also limits the set of observable LEED spots by the condition that the expression inside the brackets must be greater than zero. With increasing electron energy the number of LEED spots increases while the polar emission angle relative to the surface normal, 6 = arctan(k /kz), decreases for each spot except for the specular spot (0,0) which does not change. Eig. 2.47 shows examples of common surface unit cells and the corresponding LEED patterns. 

Figure 5 Calculated (left panel) and measured (right panel) Hel excited pliotoemission intensities for a CusPta layer on a Pt(lOO) surface. The curves are labeled with their emission angles.

Fig. 23. Surface composition x of a Rujr,- alloy electrode after electrochemical treatment at different potentials for 5 min in 0.5 mol L-1 H2S04. Electron emission angle 90°. After [82],...

Fig. 24. Ru34 and Ir4/binding energies for a RuxIrl x alloy electrode after polarizaition at 1.7 V for 5 min in 0.5 molL-1 H2S04 as a function of composition x. Electron emission angle was 90° for Ru34 and 20 for Ir4/...

Thirdly we are also interested in the electron spectroscopy method, which allows investigations on the two-center effects that influence electron emission. In particular, the richness of the ionization process lies in the possibility of measuring the doubly differential cross sections as a function of the electron emission angle and energy. This technique of electron emission spectroscopy is... 

Figure 10 Angle-resolved photoelectron spectra from the system Cu 11D -HC00 for three different emission angles, hv = 25°, E j <110>. After [251.

Figure 3. ARUPS energy distribution curves taken with Hel radiation at normal incidence and an electron emission angle of 52" shown as a function of copper coverage. The intensity of the various curves has been normalized at the Fermi level Ef The individual curves are matched to their corresponding copper coverages in monolayers by the solid lines and the saturation behavior of the interface state at approximately —1.5 eV is identified by the dashed lines. (Data from ref. 8.) (Reprinted with permission from ref. 43. Copyright 1987 American Association for the Advancement of Science.)...

Figure 5. The P-polarised emission spectrum obtained for hole injection by the thianthrene radical cation into Au(lll) for emission angle = 30° and excitation energy Eex = 3.0eV. (NB.

The spectmm from an undulator is very different, and numerous peaks result from interference effects within the undulator. When the electron acceleration is confined to the orbit plane and the emission angle very low, the radiation is strongly elliptically polarised and, in the orbit plane itself, it is to within a few per cent linearly polarised. Use of a sequence of permanent magnets with magnetisation arranged in a spiral sequence enables circularly polarised radiation to be extracted from such a helical undulator and this radiation is particularly important for magnetic studies. 

Differential ionization cross sections, differential in ejected electron energy and emission angle, were the subject of intense study during the 1970s and 1980s. Considerable progress was made in both experimental and theoretical methodologies needed to describe differential cross sections these have been reviewed in IAEA TECDOC-799 [19] and ICRU-... 

In the same manner, one can determine the total ionization cross sections ctj by integration of the doubly differential cross sections over both ejected electron energy and emission angle... 

Figure 14 Doubly differential cross sections for ionization of several low-Z molecular targets by 1-MeV protons plotted for selected ejected electron energies as a function of the emission angle. (From Refs. 47, 48, 56-58.)...

Figure 5. FDCS for electrons emitted into the scattering plane for a fixed electron energy, Ek = 4 eV, and fixed magnitude of the momentum transfer (see eqn (6)) q = 0.65 a.u., as a function of the polar electron emission angle for 3.6 MeV amu Au +d-He collisions. The following notation is used experimental data of Fischer et al, — theoretical results. The six diagrams above represent the following models (a) FBA, (b) CDW-EIS, (c) CDW-EIS+nn, (d) CDW-EIS+RHF, (e) CDW-EIS Olivera, (f) CDW-EIS Bhattacharya. The polar radius of figures (a) to (f) is lOa.w.. ...

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