Background intensity

Point defects, static disorder, and thermally induced displacements lead to an increase of the background intensity between the spots. Depending on the correlation between the scatters, the background is either homogeneous (no correlation) or... 

The last step is facilitated by the use of calibration curves of analytical-line intensity versus counting rate plotted at several levels of background intensity. All steps are rapid and simple. 

Starting from a stoichiometric, well-ordered MgCl2 film, an increasing dosage of sputtered ions leads to increasing background intensity of the LEED picture, which finally results in a complete loss of all diffraction spots [108]. Even though the process removes material from the surface, the surface... 

Figure 17.9 (A) Photoluminescence intensity traject07 (gray) of a CdSe-ZnS quantum dot. The high intensity level is the on state and the low intensity level is the off state. The trace in black is the background intensity. Reprinted with permission from reference [14] copyright [2005], American Chemical Society. (B) Schematic...

Figure 17.12 (A) Schematic presentation of deactivation and energy transfer processes in a single quantum dot placed on an Ag nanoparticle film. (B) Photoluminescence intensity trajectories of single quantum dots on a glass substrate (a) and on an Ag nanoparticle film (b). The traces in green represent background intensities. (C) Photoluminescence spectra of quantum dot solutions in the presence of...

Quantitative Analysis. Quantitative elemental analysis is possible by measuring an area under the appropriate ionization edge, making allowance for the background intensity. 

With the new VME/UNIX control system on the polarised hot-neutron normal-beam diffractometer D3 at ILL, each measurement cycle for both peak and background intensities lasts 2 s, and the (+)/(-) counting-time fractions are defined with a 1 MHz clock. There are two detector scalers and two monitor scalers ((+) and (-) states). In Table 1, we compare the flipping ratio measured for the strong 200 and the weak 600 Bragg peak reflections of a CoFe sample. As expected, the standard deviation cr (if) is improved in the case of the strong reflection (16%). 

Infrared studies show that when water is adsorbed on the surface, the background intensity in the hydroxyl region increases new bands may appear but hydrogen-bonding effects make such conclusions uncertain. If such a catalyst is then exposed to hydrogen (or deuterium), no bands due to adsorbed hydrogen (or deuterium) are observed. Thus, adsorption of water apparently occurs on the active sites and blocks out type I chemisorption. 

At least 80% of a spot s pixels should have intensities more than two standard deviations above the background intensity for that spot, at each wavelength. 

After determining the shape, size, and address of each spot in the microarray, the next step is to calculate the foreground and the background intensities. The foreground... 

Figure 11. Electron-energy-loss spectrum of crystalline boron nitride, showing the boron K-edge (at 190 eV) and the nitrogen K-edge (at 400 eV). The background intensity, delineated by the dashed curve arises from inelastic scattering by valence electrons. The hatched areas represent the measured values required for the quantitative analysis of boron ( see text) (50).

In the low frequency region where the i/(Ag-Cl) and i/(Ag-Br) vibrations are observed, significant background intensity can obscure these vibrational features if they are weak in intensity. 

Catalytic reactions of methanol on an Mo(112)-(lX2)-0 surface under a constant flow of CH3OH and 02 (10 6—10 5 Pa) were monitored as a function of reaction time by the temperature-jump method. Total amounts of the products are summarized in Table 8.3. When only CH3OH was fed, the reaction rate exponentially decayed with reaction time. After the reaction ceased in both conditions, the surfaces were covered with nearly 1 ML of C(a) (Table 8.3) and the sharp (1X2) LEED subspots of the surface before the reaction almost disappeared due to an increase in background intensity. As shown in Table 8.3, the selectivity of the reaction at 560 K is similar to that obtained by TPR (Table 8.2). The C(a) species formed with 26% selectivity cover the surface, resulting in the exponential decay of the reaction rate. O(a) species are also formed on the surface but they are desorbed as H20 by reaction with hydrogen atoms. It should be noted that neither C(a) nor a small amount of O(a) change the selectivity in this case. 

To model diffraction intensities, detector effects and the background intensity from thermal diffuse scattering must be included. A general expression for the theoretical intensity considering all of these factors is... 

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