SEELFS

SEELFS (surface extended energy loss fine structure) yes 2 0.2... 

As the table shows, a host of other teclmiques have contributed a dozen or fewer results each. It is seen that diffraction teclmiques have been very prominent in the field the major diffraction methods have been LEED, PD, SEXAFS, XSW, XRD, while others have contributed less, such as NEXAFS, RHEED, low-energy position diffraction (LEPD), high-resolution electron energy loss spectroscopy (HREELS), medium-energy electron diffraction (MEED), Auger electron diffraction (AED), SEELFS, TED and atom diffraction (AD). 

Fine structure extending several hundred eV in kinetic energy below a CEELS peak, analogous to EXAFS, have been observed in REELS. Bond lengths of adsorbed species can be determined from Surface Electron Energy-Loss Fine Structure (SEELFS) using a modified EXAFS formalism. 

M. De Crescenzi. Phys. Rev. Letts. 30,1949,1987. Use of surface electron energy-loss fine structure (SEELFS) to determine oxygen-nickel bond length changes for oxygen absorbed on Ni (100) on a function of coverage from 0 to 1.0 monolayer. 

A core hole is excited as in fine - structure techniques (see EXAFS, SEXAFS, ARPEFS, NPD, APD, EXELFS, SEELFS)... 

SEELFS Surface Electron Energy Loss Fine Structure... 

A fine structure technique similar to EXELFS, except the incident electron energies are 100-3000 eV. SEELFS is surface sensitive because of the lower excitation energy. 

The most promising techniques for obtaining detailed surface structural information about molecular adsorbates rely on electron diffraction in one way or another. These include LEED,/27,28,29/ IV-HREELS,/30/ EAPFS,/31/ SEELFS,/32,33/ EXELFS,/34,35/ ARUPS, ARXPS, ARPEFS,/36,37,38/ PE-SEXAFS, SEXAFS, EXAFS, and NEXAFS (XANES). These and other techniques have been discussed above in part 2, and were summarized in Table I. Among these techniques, LEED has been the most productive. 

By substantially increasing the electron kinetic energy in ILEED and SEELFS to 60-300 KeV, one reaches a situation that can resemble EXAFS, with electrons replacing the EXAFS photons, cf. Figure 11. Chemical selectivity, is obtained by choosing an appropriate core excitation edge. And surface sensitivity on the atomic scale exists mainly for high-surface-area materials, as with EXAFS. 

At the high energies E of SEELFS/32,33/ and ELNES,/66/ the final state has only a single active electron (the incident electron). One obtains then, for momentum transfer q, a differential cross-section/33/... 

Fig. 3.6. Variation of the lattice parameter of free Cu clusters as a function of their reciprocal diameter. Circles represent SEELFS measurements (from [32]), while the straight line corresponds to EXAFS measurements (from [33])...

A fine-strueture technique similar to EX-ELFS, exeept the ineident electron is more surface-sensitive beeause of the lower exeitation energy. A eompilation of surface structures determined using SEELFS and SEXAFS summarizing the pre-1990 literature appears in reference (123). 

D.P. Woodruff. From SEXAFS to SEELFS. Surf. Interface Anal. 11 25 (1988). 

P.R. Watson. Critical Compilation of Surface Structures Determined by Surface Extended X-Ray Absorption Fine Stmcture (SEXAFS) and Surface Extended Electron Energy Loss Spectroscopy (SEELFS). J. Pins. Chem. Ref Data 21 123 (1992). 

Different characterization techniques, for example X-ray diffraction,EXAFS, SEELFS, electron diffraction (LEED, RHEED, i SAED, and CBED ), and electron microscopy (HRTEM, WBDF ) give information about crystal structure, lattice distances, or morphology. All these techniques give average information about the shapes and the lattice distances of particle collections and of isolated particles. To obtain information about the particles at the atomic level, HRTEM is necessary. Other information about the surface structure of small particles can be obtained by Most HRTEM studies have been devoted to... 

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