Scanning photoemission microscopy

Several ways exist to image these regions of different work function. We have already discussed scanning electron and field emission microscopy in this chapter. Scanning photoemission microscopy (SPM) is carried out by scanning a focussed UV beam (beam diameter of 0.5 pm) over the surface and recording the photoemis-... 

Scanning LEED, oscillatory reactions, 39 69 Scanning photoemission microscopy, kinetic oscillations, Pt(lOO), 37 250-253 Scanning photoemission spectroscopy oscillatory reactions, 39 69... 

NEXAFS experiments on NOM can be conducted in several modes that differ in the type of detected particle and objectives of the experiment transmission (X rays transmitted through the sample), fluorescence (fluorescent X rays due to absorption of the X-ray beam), or electron yield (photo-emitted electron) (Sparks, 2003). Alternatively, the techniques can be divided into full-field applications such as transmission X-ray microscopy (TXM) and X-ray photoemission electron microscopy (PEEM), in comparison to scanning techniques such as scanning transmission X-ray microscopy (STXM) and scanning photoemission microscopy (SPEM) that provide spatial information of elemental forms. 

Several ways exist to image these regions of different work function. SEM and FEM have been discussed earlier in this chapter. As an alternative, scanning photoemission microscopy is carried out by scanning a focused UV beam (beam diameter 0.5 pm) over the surface and recording the photoemission intensity point by point. This is of course a slow procedure, but much faster imaging in real time becomes available if the electrons are collected from the entire surface in parallel, as is carried out in photoemission electron microscopy (PEEM). The lateral resolution of this technique is presently around 200 nm, but by using... 

Fig. 27. Spatial pattern formation within a 1.5 x 1-mm2 area of a Pt( 100) surface during kinetic oscillations as recorded by scanning photoemission microscopy. (From Ref. 138.)... 

Ertl, Jakubith, Rotermund, v. Oertzen, Cathode Lens] Ertl, Gerhard/Sven Jaku-bith/Harm Hinrich Rotermund/Alexander v. Oertzen Imaging of Spatial Pattern Formation in an Oscillatory Surface Reaction by Scanning Photoemission Microscopy, Journal of Chemical Physics 91 (1989), p. 4942-4948. 

Scanning Tunneling Microscopy (STM) Photoemission Electron Microscopy (PEEM) Ellipsometry Microscopy for Surface Imaging (EMSI)... 

Weaver, J. H. 1992 Fullerenes and fullerides photoemission and scanning tunneling microscopy studies. Acc. Chem. Res. 25, 143-149. 

In this section, we will present and discuss results from Sc2 C84, which is the most widely studied dimetallofullerene to date. Early scanning tunnelling microscopy [26] and transmission electron microscopic [27] investigations provided evidence in favour of the endohedral structure of this system, which was later confirmed by x-ray diffraction experiments utilising maximum entropy methods [28]. Before experimental data from this system were available, the Sc ions were predicted to be divalent from quantum chemical calculations [29]. Subsequent data from vibrational spectroscopy [30,31], core-level photoemission [32] and further theory [33] on this system were indeed interpreted in terms of divalent Sc ions. 

Scanning tunneling microscopy (STM) Photoemission electron microscopy (PEEM)... 

Fermi level of the metal [19]. This is the value that one measures with scanning tunneling microscopy (see Chapter 7) and with photoemission of adsorbed xenon (see Chapter 3). Thus, on a heterogeneous surface we have local work functions for each type of site, and the macroscopic work function is an average over these values. 

Lin DS, Ku TS, Sheu TJ (1999) Thermal reactions of phosphine with Si(100) a combined photoemission and scanning-tunneling-microscopy study, Surf. Sci. 424 7-18... 

Lin DS, Ku TS, Chen RP (2000) Interaction of phosphine with Si(100) from core-level photoemission and real-time scanning tunneling microscopy, Phys. Rev. B 61 2799-2805... 

In summary, the results of TDS [13], photoemission [13,45] and scanning tunnelling microscopy [24,45] indicate that at low sulphur coverages the interactions between S and Ag on Ru(OOOl) can be classified as repulsive, in the sense that there is weakening of the Ru-Ag bond and no mixing of the adsorbates. Once the ruthenium substrate becomes saturated with sulphur, then attractive interactions between silver and sulphur are possible and AgS is formed [13,45]. Very similar trends are observed for the coadsorption of sulphur and copper on Ru(OOOl) [13,23]. 

Borgschulte et al. [84] concluded from photoemission and scanning tunneling microscopy studies (STM/STS) that this critical cap layer thickness is related to inactivation of Pd by encapsulation of the Pd islands by yttrium oxide or hydroxide strong metal-support interaction (SMS I effect). The substitution of Pd by cheaper, preferably transparent, catalytic cap layers is desirable, especially for smart window devices. In this respect, the catalytic properties of transition metal oxides [85] for storage materials could also prove to be useful for smart windows. 

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