Angle-resolved spectrum

Fig. 13.7. Angle-resolved spectrum of an ultrashort pulse propagating in water (left panel). The dashed lines represent the loci of spectral energy concentration predicted from an effective three-wave mixing argument. The right panel compares these loci to the manifold that supports the spectrum of 2-invariant X-wave solutions that propagate without distortions...

Fig. 48. Comparison of an angle-resolved spectrum at resonance (110 eV) with a spectrum at Av = 30eV in single-crystal USb2. Note the improved momentum and energy resolution. The sharp near-E p spike at /iV = 30eV is no more than 30 meV FWHM, thus making it the sharpest f-electron feature ever observed. A difference spectrum of scraped polycrystal UPt, is included to illustrate previous measurements of 5f-DOS width.

In the investigations of molecular adsorption reported here our philosophy has been to first determine the orientation of the adsorbed molecule or molecular fragment using NEXAFS and/or photoelectron diffraction. Using photoemission selection rules we then assign the observed spectral features in the photoelectron spectrum. On the basis of Koopmans theorem a comparison with a quantum chemical cluster calculation is then possible, should this be available. All three types of measurement can be performed with the same angle-resolving photoelectron spectrometer, but on different monochromators. In the next Section we briefly discuss the techniques. The third Section is devoted to three examples of the combined application of NEXAFS and photoemission, whereby the first - C0/Ni(100) - is chosen mainly for didactic reasons. The results for the systems CN/Pd(111) and HCOO/Cu(110) show, however, the power of this approach in situations where no a priori predictions of structure are possible. 

Figure 4 Angle-resolved photoelectron spectra for Ni 100] ( 2x/2)R45°-CO. hv = 32 eV (a) angle of incidence, o = 60°, polar angle of emission, 0 = 0°. (b) a = 0 , 0 = 50°, Elk). Inset Gas phase photoelectron spectrum of CO at the same photon energy. After [10] and [11].

Fig. 31. Stacked plot of the heteronuclear two-dimensional J-resolved spectrum of cured, carbon black filled, natural rubber. The proton flip experiment was used with high-power proton decoupling during the detection time. The experiment was performed with the sample spinning at the magic angle (reprinted from Ref. 1911 with permission)...

These conclusions were supported by results obtained from angle-resolved XPS. The band near 932.4 eV in the Cu(2pV2) photoelectron spectrum of the mirror coated with y-APS increased in intensity relative to that near 934.9 eV when the take-off angle was increased from 15° to 75°. Similarly, the band near 336.8 eV in the Auger spectrum also increased in intensity relative to that near 340.0 eV. Such behavior would be expected if the bands near 932.4 eV in the photoelectron spectrum and near 336.8 eV in the Auger spectrum were related to an oxide that was covered by a thin film of silane. 

Results. It was found that XPS spectra of mixed oxides could be interpreted using only the U + and U + oxidation states. A 1.3 + 0.2 eV shift existed between these two states which was maintained for mixed valence oxides. The U(4f ) photoelectron spectra for UO2 is shown in Fig. 4a while the spectra for a surface oxidized at - -300 mV is shown in Fig. 4b. The peak fits obtained, maintaining the 1.3 eV separation between UO2 (+4) and U03(-)-6), show good fits to the data and were used to determine the ratio of U +/U + in the surface oxide. Angle resolved XPS measurements indicated that the surface oxide was sufficiently thick after two minutes of oxidation to prevent any U +(U02) contribution to the spectrum from the UO2 substrate. 

Fig. 3. Angle resolved He ll ultraviolet photoemission spectrum of a V205(010) surface sample taken at normal incidence from Refs. [93,94].

Thus, the dependence of the SEFS spectrum on the angular orientation of the sample with a monocrystal surface in angle-resolved experiments is a consequence of the influence on electron scattering of the local atomic structure oriented in a specific manner. The angular orientation of the atomic surface plane of the sample can be taken into account if in Eq. (38), instead of x ip, Rj), an interference term of the type of Eq. (20) is used. The same approach can be used in the calculation of the FS of the spectrum of secondary electrons from monocrystal surfaces and of their angular dependence. In the present work we have restricted ourselves to the simplest case, namely, the secondary electron emission from a polycrystal. As a result, there is no angular dependence of the SEFS spectrum in Eq. (38). 

Angle-resolved linear dichroism (LD) measurements across the absorption spectrum of chlorophyll yield the order parameter of the effective transition moment. 

The XPS spectrum of one monolayer of 11 on Au shows two N(ls) peaks.An angle-resolved XPS spectrum shows that the N atoms of the CN group are closer to the Au substrate, than the quinolinium The ionicity of 11 in solution is confirmed by its dipole moment its ionicity as an LB multilayer and monolayer was confirmed by XPS and optical spectroscopy. " The valence-band portion of the XPS spectrum agrees roughly with the density of molecnlar energy states. The contact angle of a drop of water is 92° above a monolayer of 11 deposited on fresh hydrophilic Au (this exposes the nonpolar tail to water). The orientation... 

Two F NMR spectra of KAsFe are shown in Figure 4.64. Without spinning about the magic angle we observe a very broad featureless spectrum, but with MAS we obtain a well-resolved spectrum, which allows resolution of the coupling between the F and As (7=3/2) nuclei. 

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