Photoelectron signals

Equation (8) therefore allows us to use directly tabulated subshell photo-ionization cross sections (p) instead of mass absorption coefficients (a). F is the integrated photoelectron signal from an appropriate subshell of the monolayer adatom Yg the integrated signal from the relevant subshell of the substrate which is not simply the area of the core-level peak p and p. 

It should be emphasized that the photoelectron signal is not generated entirely by the surface atoms. The precise definition of X (the escape depth ) is the depth from which a fraction /e of the electrons escape without losing energy through inelastic collisions. This follows from... 

Figure 6.17 (a) Measured photoelectron spectrum together with calculated photoelectron signals... 

The 3-photon ionization photoelectron spectrum, plotted as the photoelectron signal intensity as a function of the binding energy of the Rydberg states, is shown in Fig. 2. Three series of Rydberg peaks, with quantum defects of 0.93, 0.76, and 0.15 are obtained. From the quantum... 

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. 

Fig. 15.9. Depth profiles of the Pt Af and 2s photoelectron signal of the electron beam-evaporated Pt layer on Si and the concentration profiles of Pt, Si, O and C. (Reprinted from C. U. Maier, Hydrogen Evolution on Platinum-Coated p-Silicon Photocathodes, Int. J. Hydrogen Energy21 840,1996. Reproduced with permission of the International Association for Hydrogen Energy.)...

The photoelectron signal as a function of the laser intensity was measured at two temperatures for the LC film and is shown in Fig. 9. At room temperature the photoemission signal depends linearly on the laser intensity, indicating a single photon photoemission process. From the high energy cut-off in Fig. 9a we deduce that the workfunction is about 3.9 eV, much lower than the workfunction of the bare... 

Induced Photoelectron Signals from Different Shells in 72 Elements, Discuss. Faraday Soc. (1972) 54,269-276. 

Berthou, H., Jorgensen, C. K., Relative Photoelectron Signal Intensities... 

Figure 4.7. These diagrams are designed to emphasize the reproducibility of various physical parameters in monolayer assemblies of different thicknesses a) reciprocal capacitance per unit area versus number of monolayers of cad-mium arachidate on an aluminum substrate (see r erence 38), (Jb) absorption intensity versus number of monolayers for the symmetric carboxylate stretching mode of cadmium arachidate at 1432 cm (see r erence 39), (c) count rate of rays versus number of layers of barium stearate labeled with (see reference 40), and d) X-ray photoelectron signal (XPS) intensity versus number of layers of cadmium dimethylarcwhidate on silver (see reference 28).

In this discussion we have so far ignored the photoelectron signals from valence band states. A peak due to such states in a telluride can be distinctly seen in Fig. 8 near... 

Fig. 4.5 Temporal profiles of total photoelectron signals in (l + T)REMPlof(a) pyrazine-li4 and (b) pyrazine-di from Ref [13]. The observed data solid circles with error bars) are well explained by three components the single-exponential decay of S2 dotted line), the corresponding increase in S dashed line) in the positive-time delay, and the single-exponential decay of Si dash-dotted line) in the negative-time delay. The fitting result is shown as a solid line...

High-resolution XPS provides quantitative evidence for shell growth based on the finite escape depth, X, of photoelectrons from the core atoms 26]. The typical escape depths are on the order of the shell thickness, and the photoelectron signal from core atoms should decrease accordingly in the core-shell structure [68]. 

The main obstacle to photoelectron spectroscopy at elevated pressures is the scattering of electrons by gas-phase molecules. The attenuation of the photoelectron signal follows Beer s law I = with I as the signal at pressure p Jq... 

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