SRPES

Fig. 2 SRPES spectra from Sn02 surfaces from the (110) surface (I) and the (101) surface (II). (a) clean surface, (b) Cu-covered surface (0.7 monolayer), (c) the sample annealed to 500K in IxlO" mbar O2 for 20 min., and (d) the sample annealed to 600K in 1x10 mbar O2 for 20 min.

Accurate investigation of the valence ionization spectra is important subject to elucidate the electronic structure of molecules. Ionization spectra of five-membered aromatic compounds have also been intensively studied. The high-resolution synchrotron radiation photoelectron spectra (SRPES) of furan and thiophene were measured and analyzed with asymmetry parameter up to about 40 eV [63,64]. The electron momentum spectroscopy (EMS) was also applied to furan up to 30-40 eV [65]. The ionization spectra of these molecules were also studied by several theoretical methods. However, there were some controversial assignments even for the outer-valence region, in particular for the peak position of Ibi(TTi) state and the inner-valence spectra have not been theoretically reproduced. 

The SAC-CI general-R method is useful for investigating the satellite spectrum of molecules it describes the multi-electron process very accurately. The SAC-CI spectrum [54] of furan is shown with the SRPES spectrum [64] in Fig. 39.3. The SAC-CI method reproduces the spectrum very accurately in both peak positions and intensities. In the outer-valence region, some congested main peaks exist and the theory gives accurate assignments for them. In particular, the tti state was calculated to split into two peaks at... 

SrPe Oa, and for K2pe 04, These figures are chemically more satisfactory than any interpretation using the WWJ model. 

Core SrPe Oig nanoparticles-r/02 nanocrystals were also synthesized as magnetic photocatalytic particles [366]. In this case the photocatalyst particles are recovered from the treated water stream by applying an external magnetic field (see Table 6). 

Among the related methods, specific experimental designs for applications are emphasized. As in-system synchrotron radiation photoelectron spectroscopy (SRPES) will be applied below for chemical analysis of electrochemically conditioned surfaces, this method will be presented first, followed by high-resolution electron energy loss spectroscopy (HREELS), photoelectron emission microscopy (PEEM), and X-ray emission spectroscopy (XES). The latter three methods are rather briefly presented due to the more singular results, discussed in Sections 2.4-2.6, that have been obtained with them. Although ultraviolet photoelectron spectroscopy (UPS) is an important method to determine band bendings and surface dipoles of semiconductors, the reader is referred to a rather recent article where all basic features of the method have been elaborated for the analysis of semiconductors [150]. 

Figure 2.26 Schematic of the SoLiAS used for SRPES at BESSY level 1 is the conditioning level with the electrochemical vessel (EC see Figure 2.27) attached, facilities for etching, and a buffer chamber (BC) for outgassing of samples that underwent wet treatments after transfer to the manipulator M, measurement levels 2 and 3 can be assessed at level 2, UPS LEED and quadrupole mass spectroscopy (QMS)...

SRPES allows one to tune the photon energy to the desired surface sensitivity within the limits of XPS. As the mean inelastic scattering length for photoelectrons... 

Figure 2.30 SRPE spectrum of the Si 2p core level for a chemically H-terminated sample and a sample where silicon oxide has been formed due to hole injection into the Si valence band and/or surface states the pronounced peak at Eb = 103.5eV,...

Figure 2.40 SRPES data for anodic photocorrosion of n-Si(lll) in dilute NH4F solution in the divalent dissolution regime (cf Figure 2.39, region i) (a) sample emersion slightly anodic from open circuit potential (b) sample emersion near first photocurrent maximum.

Figure 2.48 SRPES data for (a) the Si 2p and (b) the O Is core level at high surface sensitivity, tuned by the photon energy the arrows in (a) indicate positions of reaction intermediates obtained from deconvolution.

Table 2.1 Reaction intermediates identified by SRPES Si 2p spectrum deconvolution after treatment in 2M NaOH according to the conditioning procedure shown in Figure 2.47 (for...

Figure 2.50 SRPE envelope and high surface sensitivity. Bottom escape...

SRPES measurements have been performed for three conditions along the polarization curve in Figure 2.90, indicated by Ci, C2, and at OV (SCE). First, the energetic situation at the Si-electrolyte contact is reviewed (Figure 2.84) as mentioned above for aUgnment between electrolyte levels and the Si band structure, the measured flatband potential of -0.48 V vs. SCE is used. The Pt deposition occurs in two major steps, for example, Pt(IV)/(II) and Pt(II)/(0). The redox levels are indicated in the figure and the reaction scheme is... 

Figure 2.90 Protocol for Pt electrodeposition on chemically H-terminated n-Si(lll) for model experiments on surface chemistry using the SoLiAS at undulator U49/2 at Bessy ii, recorded in the in-system apparatus shown in Figure 2.27. Three conditions have been analyzed by SRPES deposition under depletion (peak C ), and accumulation (C2)...

Figure 2.91 Si 2p core level, measured by SRPES at a photon energy of 170eV where the inelastic mean free scattering length for photoelectrons, has a minimum resulting in monolayer surface sensitivity ...

The SRPES results show that silicon oxide is formed during Pt deposition due to the scanning conditioning procedure (peak C2). The oxide thickness on H-terminated... 

Figure 2.97 Energy scheme for interpretation of the SRPES data obtained at C and open circuit potential in Eigure Z9. The left-hand side shows the semiconductor band bending at open circuit potential, the Rj" surface states, and the Pt deposition levels also shown is the inversion layer extension the...

The use of surface-sensitive techniques for the development of photoelectrochemical devices that convert solar energy has been described. The essence of this approach is the control of interfacial properties. This is achieved by a combination of empirical procedures that are developed into directed approaches of interface modification for desired electronic, chemical, and structural properties by a feedback between preparation and analysis. Besides the multitude of commercially available surface analytical techniques employed (AFM, STM, TEM, HRSEM, HREELS, SRPES, FTIR), novel methods have been developed such as Brewster angle refiectometry and stationary microwave reflectivity. The detailed highly surface-sensitive analysis of the surface chemistry of samples where electrochemical currents have passed has become possible by the development of in-system photoelectron spectroscopy and HREELS. 

The photoelectron emission spectroscopies (UPS/UPES, XPS/XEPS DSPES, SRPES, SECSA, FED, ARPS/ARPES)... 

SRPES synchrotron radiation photoelectron spectroscopy. For photon energies less than 300 eV also SXPS soft X-ray photoelectron spectroscopy. 

SMC-II SMC, low-pressure molding SRPE solid redox polymerization electrode... 

Figure 6.2 The temperature and frequency dependence of the relative permittivity, s, of SrPe Jag O ceramics. Note the logarithmic scales on each axis...

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