X-rays take off angle

ESCA X-ray take-off angles were set as described in the text. 

XPS can be used to determine the composition of a solid as a function of distance away from the surface and into the bulk of the solid. Such a depth profile can be constructed in two ways. One way in which a depth profile can be constructed is by using a beam of inert gas ions to sputter away material from the surface of the sample and to then record the XPS spectrum. If this procedure is repeated several times, a profile showing the composition of the material as a function of sputtering time and thus of depth into the sample can be constructed. Another way to construct a depth profile involves tilting the sample with respect to the X-ray beam. In Fig. 17A, the take-off angle or the angle between the sample surface and the direction of propagation of the ejected photoelectrons is 90 . In... 

The X-rays leave the specimen at a take-off angle 4>, are collimated by two slits Si and S2 before falling on to a crystal (bent to a radius 2R, where R is the... 

In this expression, n/p] pec is the mass absorption coefficient of X-rays from element A in the specimen, a is the detector take-off angle, p is the density of the specimen... 

In electron probe microanalysis the surface characteristics of the specimen are also of importance. Figure 8.34 illustrates how an uneven surface can lead to variable attenuation of the emitted X-rays and the importance of the angle between detector and specimen surface being as near 90° as possible. Such a high take off angle will minimize the surface effects. 

Determine the take-off angle from the X-ray tube. This controls the beam size, and a resultant beam size of approximately 0.5x0.5 mm is about right. Use the maximum take-off angle consistent with this size. Ahgn the instrument so that the beam conditioner points at the source at this take-off angle. 

The XPS spectra were recorded on a Surface Science Laboratories small spot system using a monochromatized A1K X-ray radiation source. The take-off angle used for these measurements was 35°. Full details of the methods used in interpreting the XPS data have been described elsewhere [14], Data reduction was done using Surface Science Laboratories software version 8.0. This software utilizes a least squares curve fitting approach with only chi square statistics for goodness of the calculated fit to the experimental data. 

X-Ray diffraction data of atenolol are presented in Table 7 (5) The diffraction spectrum was produced by monochromatic radiation from the CuK line (1.542 a) which was obtained by excitation at 55 kV and 2o mA. Recording conditions were as follows. Optics detector slit o.2° M.R. soller slit, 5° beam slit, o.ooo7 Ni filter, 3° take off angle. Goniometer scan at 2°, 2o/min. Detector amplifier gain 16 coarse, 9 1 fine. Scintillation co-... 

The XPS (X-ray Photoelectron Spectroscopy) and IR analyses have been described in detail elsewhere [14], Here, only some important facts are summarized. The XPS data acquisition was performed with a SAGE 150 Spectrometer (Specs, Berlin, Germany) using a non-monochromatized MgK or AIKq, radiation with 12.5 kV and 250 W settings at a pressure 10-7 Pa in the analysis chamber. XPS spectra were acquired in the constant analyzer energy (CAE) mode at 90° take-off angle. Peak analysis was performed using the peak fit routine from Specs. 

Other variables, such as the distance between X-ray detector and specimen, tilting angle of specimen holder, specimen height, and take-off angle, should be... 

Figure 3 shows the absolute Cls signal intensity derived from a homogeneous polymer film as a function of the electron take-off angle, 0, in an AEI ES 200B X-ray photoelectron spectrometer (4). For this spectrometer the angle between the X-ray source and analyzer, i ) is fixed at 90. It is clear from Figure 2 that if the sample is turned to face away from either the X-ray... 

Figure 6.24 Photoelectron and X-ray excited Auger spectra taken at various take-off angles from the surface of the TMS film treated with an O2 plasma, showing how the contribution from the underlying bulk TMS film disappears at low take-off angle, revealing the layered structure left after the plasma treatment.

The surfaces of ACFs were analyzed using a VG Scientific LAB MK-Il X-ray photoelectron spectrometer (XPS). The spectra were collected using a MgK X-ray source (I2S3.6 eV). The pressure inside the chamber was held below SxlO torr during analysis. Both survey XPS spectra are recorded at a 45 ° take-off angle. 

X-Ray Measurements. A Picker automatic four-circle diffractometer, equipped with a hne focus Mo anode tube, used for data collection. Twelve high-angle reflections (using Mo Koc, ( = 0.709261 A) radiation, at a take-off angle of 2 j were used for a least-squares refinement of the cell parameters. Data were collected and treated as described in a recent article.Three standard reflections 040,080, and 600 were monitored every 200 reflections and showed no decay in intensity during the course of data collection. 

Figure 2.9. The schematic showing collimation of the incident x-ray beam by using a single divergence slit (top, left) or coupled divergence slits (top, right). The schematic on the bottom left illustrates the size of the source (5) when the projection of the cathode ) is viewed at a take-off angle, v . Equation 2.5 is derived on the bottom, right.

As established in Chapter 2 (see Figure 2.9), this is a valid approximation because the typical projection of the 1 mm wide line focus of the x-ray tube, visible at a small take-off angle (usually 5 to 6 ), results in the source size on the order of 0.1 mm. 

Figure 6.13 Potential interference of X-ray detection due to low take-off angle in the SEM.

Since there is no issue of polarisation to consider (unlike synchrotron X-rays), and given the massive construction of neutron facilities, neutron diffractometers operate in the horizontal plane, and only a single-bounce monochromator is necessary. The position of the diffractometer on the floor is usually fixed, thus defining the monochromator take-off angle 20m- A wavelength is selected by rotating the monochromator crystal about its vertical axis... 

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