Auger signal

The measured Auger signal is proportional to the number of atoms sampled. In the derivative mode of data acquisition this is frequently not the case, for example, if an inappropriate modulation voltage is used or if the line shape has... 

Figure 2, Variations of the 0/Ti Auger signal ratio on the Ti02(100) surface heating and cooling under the electron beam.

When the electron beam enters the sample, it penetrates a small volume, typically about one cubic micron (10-18m3 ). X-rays are emitted from most of this volume, but Auger signals arise from much smaller volumes, down to about 3 x 10 25m3. The Auger analytical volume depends on the beam diameter and on the escape depth of the Auger electrons. The mean free paths of the electrons depend on their energies and on the sample material, with values up to 25 nm under practical analytical conditions. 

Fig. 11. Graphs of the Auger signals resulting from exposure to various sulfur containing precursors as a function of potentials. Adapted from ref. [279],...

Fig. 67. Graphs of the Cd/Te ratios from Auger electron spectroscopy as a function the potentials used to deposit the second atomic layer in the formation of CdTe monolayers on Au(lll). The Auger signals have been corrected for sensitivity factors, so the ratios are an approximation of the atomic ratios. A) Te deposited first at 0.15 V, B) Te deposited first at 0.10 V, C) Cd deposited first at —0.6 V, D) Cd deposited first at —0.7 V. Adapted from ref. [236],...

Figure 6 shows that all of the chemisorbed oxygen is reactive. Here, a polycrystalline Pt surface at 370K is exposed to various amounts of O2 as indicated on the abscissa and, after termination of the O2 input, titrated with CO. As indicated by the four sets of dashed lines in the figure, all of the oxygen Auger signal vanishes. 

Figure 6. Peak-to-peak oxygen Auger signal (517 eV) as a junction of oxygen exposure to polycrystalline Pt at 370 K. Oxygen pressures (Pa) are 1.13 X 10 6 1.29 X 10 6 ( 7), 2.93 X...

Figure 7. Steady-state oxygen Auger signal on Pt at 483 K as a function of CO pressure for several fixed O pressures. Triangles enclosed in brackets ((A)) indicate the presence of a detectable concentration of adsorbed carbon monoxide. The fixed oxygen pressures (torr) were 10 8 (QJ,...

Auger spectroscopy yields data for molecular layers from which relatively accurate and precise packing densities and elemental analyses are obtained. Two methods are available, allowing verification of precision and self-consistency. The first of these methods is based upon measurement of elemental Auger signals (Iq, In, Iq, etc.), while the other method measures the at-... 

Figure 2. Auger signal ratios and packing densities of NA adsorbed at Pt(lll). Experimental conditions adsorption from 10 mM KF adjusted to pH 7 with HF, followed by rinsing with 1 mM HF (pH 3.3) temperature, 23 1 C electron beam at normal incidence, 100 nA, 2000 eV. A. Auger signal ratios 0(/Ipt) and (Ipt/Ip,) for NA adsorbed at -0.2 V vs. Ag/AgCl reference. B. Packing density of NA adsorbed at —0.2 V. Continued on next page.

Fig. 3.4. Normalized carbon Auger signal from silicon and oxidized silicon as a function of the dosage of 500 eV CF3 ions incident on these surfaces. (See Ref. ")...

At time t = 0, p0l is reduced to zero and the oxygen Auger signal is followed as a function of time. It is seen that 90 decreases essentially linearly with time for 0O above a value 0OC. For 90 < 90c, the decrease in coverage with time is closer to the exponential form expected for a reaction that is first order in 0o. It can also be seen from Fig. 42 that the slope of the linear decrease is independent of the substrate temperature over a wide range. The slope is, however, directly proportional to pCQ (as is shown in Fig. 43) indicating that the reaction order in pco is unity. It may, therefore, be concluded that in the temperature and pressure range for which 9C0 < 9 o and 0O > 0OC, the reaction is first order in pco and zero order in 0O. 

Fig. 3.29 Auger sputter depth profile of a layered Zr02/SiC>2/Si model catalyst. While the sample is continuously bombarded with argon ions which remove the outer layers of the sample, the Auger signals of Zr, O, Si and C are measured as a function of time. The depth profile is a plot of Auger peak intensities against sputter time. The profile indicates that the outer layer of the model...

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