Absorption and Background Correction

For USAXS and SAXS studies in normal-transmission geometry it is more convenient to carry out this step after the correction for absorption and background, because in these cases absorption and background correction are no function of the scattering angle. 

For other geometries the center of the scattering pattern, its orientation, the pixel size of the detector and its distance from the sample must be operated first in order to align the scattering pattern. 

If scattering curves are processed, the center is simply a channel number of the detector and centering is accomplished by subtracting this channel number from all other channel numbers. 

If the principal axis of the sample is moving during the experiment, then every frame has to be aligned individually while proceeding through the sequence of frames. In this case it is helpful if the interactive procedure remembers the last set of alignment parameters and the operator only invokes incremental corrections, whenever they become necessary. 

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Moreover, the intensity is additionally increasingly dampened with increasing scattering angle. The corresponding absorption and background correction... 

Cobalt. Cobalt was determined colorlmetrically as the nltroso-R salt (13). The use of any nltroso salt comes under scrutiny as a suspected carcinogen. Cobalt can be analyzed at 240.7 nm with an air-acetylene flame this analytical line is subject to line broadening and self-absorption necessitating background correction. The analyst should be aware that greater than 2000 ppm nickel and chromium can be interferences. 

In the two line method the total absorbance (atomic absorption and background absorption) is measured at the resonance line of the analyte emitted by the hollow cathode lamp and the non-specific absorbance (background absorption) is measured at a nearby line where the analyte atoms do not absorb. Alternatively, another hollow cathode lamp of an element not present in the sample can be used. The line for the background absorbance measurement must be close to the analyte line. One of the problems is to find a convenient nearby line. The maximum permitted distance apart is 10 nm for most of the elements. To ensure there is accurate correction, the background must be constant within the range of these two lines. Another factor which must be considered is that for successive... 

See also Atomic Absorption Spectrometry Interferences and Background Correction Flame Electrothermal Vapor Generation. Atomic Spectrometry Overview. Flow Injection Analysis Principles. 

ATOMIC ABSORPTION SPECTROMETRY/Interferences and Background Correction 157... 

ATOMIC ABSORPTION SPECTROMETRY/ Interferences and Background Correction 161... 

See also Atomic Absorption Spectrometry Principles and Instrumentation Interferences and Background Correction. Atomic Mass Spectrometry Inductively Coupled Plasma Laser Microprobe. Liquid Chromatography Column Technology. 

See ATOMIC ABSORPTION SPECTROMETRY Interferences and Background Correction. ATOMIC EMISSION SPECTROMETRY Interferences and Background Correction... 

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