Partial electron yield

Soft X-ray absorption measurements are done at low-energy synchrotron X-ray facilities such as the UV ring at NSLS or the Advanced Photon Source (APS) at Lawrence Berkeley National Laboratory (LBNL). The beam size is typically 1 mm in diameter. The electron yield data are usually obtained in the total electron yield (EY) mode, measuring the current from a channel electron multiplier (Channeltron). Sometimes a voltage bias is applied to increase surface sensitivity. This is referred to as the partial electron yield (PEY) mode. Huorescence yield (EY) data are recorded using a windowless energy dispersive Si (Li) detector. The experiments are conducted in vacuum at a pressure of 2 X 10 torr. 

The rate of ethylidyne formation was measured by recording the partial electron yield signal as a function of time after setting the crystal temperature to a preestablished value. An example of the results is shown in Figure 2 for the conversion of at... 

Fig. 13 Carbon K-edge partial electron yield (PEY) NEXAFS spectra collected from the CMPE-SAM (top) and OTS-SAM (bottom). The arrow marks the position of the Is tt transition for phenyl C = C, present only in the CMPE-SAM sample. (Reproduced with permission from [76])...

Fig. 14 Partial electron yield (PEY) NEXAFS intensity measured at E = 284.2 eV as a function of the position on the substrates containing the initiator gradients made of CMPEiPO mixtures (w/w) 1 1 (solid line), 1 2 (dashed line), 1 5 (dotted line), and 1 10 (dash-dotted line)...

Figure 2. Upper-panel Fluorescence-yield near-edge spectra of a NiO/Ni(100) layer measured before and after annealing the surface to 800 K. Lower-panel Simultaneous measurement of the partial electron-yield of the same NiO/Ni(100) surface.

Figure 24.4 Comparison of carbon K-edge features of VC/V(110), VC powder and graphite. The NEXAFS spectra were recorded by measuring the partial electron-yield.

Figure 3 K-edge NEXAFS spectra of a)PMPO, b) PVMK, and c) PMDA-ODA PI as a function of increasing chromium coverage. Abscissa is partial electron yield, centered at 42 eV with a bandpass of 8 eV.

The synchrotron experiments were performed at beamline UE52-PGM at BESSY, Berlin. Substrates and films were prepared at the end station in a UHV preparation chamber at a base pressure of 5 x 10mbar and transferred into the measurement chamber without exposure to air. The NEXAFS spectra on sapphire substrates were recorded by measuring the partial electron yield with a dedicated channeltron detector, the spectra on Au substrates were measured using the sample current. Energy calibration and intensity normalisation were carefully done according to [18]. 

NEXAFS experiments were carried out at the National Synchrotron Light Source (NSLS), Brookhaven National Lab (New York), on Exxon Beamline U1A in the partial electron yield mode for various irradiation angles between normal and grazing incidence. To compensate for the severe charging of the samples. 

FIGURE 8.1 NEXAFS carbon K-edge partial electron yield spectra for a Cj trichlorosi-lane SAM, C,2 trichlorosilane SAM, and C30 trichlorosilane SAM at normal incidence when 6 = 90° (solid curve) and at glancing incidence when 0 = 20° (dashed curve) between E and surface normal. 

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