Photoelectrons intensities

PED Photoelectron diffraction [107-109] x-rays (40-1500 eV) eject photoelectrons intensity measured as a function of energy and angle Surface structure... 

With the X parameter in hand, the Beer-Lambert expression describes how the photoelectron intensity will decrease as a function of depth into the... 

Xps spectra also bear a relationship between photoelectron intensity and number of surface atoms sampled (19,27). Quantitation of these data can be achieved with a precision to within ca 20%. For a homogeneous sample analy2ed in a fixed geometry, the relationship between xps intensity and number of atoms is given by... 

Fig. 30. Contour plot of photoelectron-photodissociation coincidence spectrum as a distribution of photoelectron intensity (dark shade = low, light shade = high) against the electron binding energy and relative translational energy of the photofragments. Also shown on the left and at the bottom are the partially averaged distributions for the translational energy release and the electron binding energy, respectively.

Fig. 3.9. Left photoelectron intensity from TbTe3 surface as a function of energy and momentum for different time delays, showing the ultrafast closing of the CFW gap marked with a dot. Right Time-dependent binding energy of the Te band (lower trace) and the CB (upper trace), exhibiting a periodic modulation at 2.3 and 3.6 THz, respectively, under strong excitation fluence (2mJ/ cm2). From [22]...

Figure 7.23 Ordering of adsorbates on a surface into islands gives rise to regions of different work function, which can be imaged because of the associated differences in photoelectron intensity. The principle forms the basis of photoemission electron microscopy (PEEM). The same principle underlies the imaging of single molecules in the field electron microscope (FEM) (see also Fig. 7.9).

III. Calculation of Surface Concentrations from Photoelectron Intensity Data... 

The depth of analysis (d) in XPS is approximately given by 3/ sin 6 [21] where l is the mean escape depth and 6 is the take-off angle of the photoelectron with respect to the sample surface plane. Thicknesses of surface coverage layers on different samples were estimated from the attenuation of the XPS signal from the substrate by the overlayer using the relation [22] In [/ // +1] = d/l sin 6, where d is the overlayer thickness, R is the ratio of photoelectron signal intensities from the overlayer to substrate of any particular element, and is the photoelectron intensity from the same element of infinite thickness. 

In Figure 1 we show the raw ARPES data as image plots, for several cuts in the momentum space, from the nodal TY (panel aO and bO) to half way towards the M point (n, 0) (panels a6 and b6), for the two isotope substituted samples. The color scale represents the photoelectron intensity versus the momentum and binding energy, with maximum in black and minimum in... 

The photoelectron intensity for a given element A is determined by the product of this element s concentration level and its effective photo-ionisation cross section (for the orbital under consideration) For this element, the number of photoelectrons emitted is thus proportional to A fraction T of these electrons is effectively transmitted to the... 

Figure 11 Cu(100)c(2 x 2)-0. Azimuthal distribution of 0 s photoelectron intensity at a polar emission angle 6 = 7°. In the upper half of the figure the dotted curve represents the raw data and the full curve the data with the minimum value subtracted. The lower half of the figure is a theoretical curve for O atoms in fourfold holes at a z-position co-planar with the surface Cu atoms...

In a theoretical description for the angle-dependent photoelectron-intensity variation, one considers the wave nature of the photoelectrons. The photon-emitted electron is scattered by the surrounding atoms. The interference of the photoelectron wave with its scattered waves results in an intensity modulation that depends on the geometrical arrangement of the scatterers (lattice atoms) and the atomic scattering factor. This ultimately is responsible for the angle dependency of the photoelectron intensity and is therefore directly related to the structure of the surface layers. For a... 

Tab. 11.2. Si zes of the various regions in the nanocrystals, CdS-4.5 and CdS-2.2 obtained from an analysis of the photoelectron intensities. The symbols Ro, Ri and R2 are the radii of the core, core + surface shell, and core + surface shell + capping layer.

The model for the calculation of surface concentrations utilized here is that of Dreiling (JJ.). The measured photoelectron intensity... 

In the present work interest centers upon overlayers of alkali compounds on the Cu/ZnO catalyst. The Zn 2p photoelectron intensity is taken as the internal reference signal anl hence the species i is Zn and species j is an alkali ion. The escape depth estimated... 

As a further test, the molecular beam shutter was opened and closed several times with an interval time of roughly 150s. The resultant changes in photoelectron intensity are shown in the inset of Fig. 2b). Repeated at several temperatures, the rise in intensity due to second layer depletion is plotted with respect to... 

Fig. 2. a) Photoelectron intensity vs normalized time in ML, intensity scale bar indicates corresponding change in workfunction. Insets PEEM images (20 pm) of surface taken at key stages of growth, b) Photoelectron intensity versus square-root-time at various temperatures. Inset photoelectron intensity vs time at 115°C with molecular beam shutter periodically opened and shut. 

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