The Units of Absolute Scattering Intensity

The radiation strength of a single electron is determined by elementary quantities that need not be considered in materials science. These quantities and the characteristics of the detector are automatically considered if the primary beam intensity is directly measured or indirectly determined by means of a secondary standard. 

Electron Density. Continuing the preceding considerations, calibration to absolute intensity means normalization to the scattering of a single electron , le that can be expressed in electron units, [e.u.]. Inevitably a calibration to absolute units involves also a normalization with respect to the irradiated volume V. Thus, for the field of materials science a suitable dimension of the absolute intensity is [I/V = e.u./nm - The intensity measured in the detector is originating from a material with an average electron density of 400 electrons per nanometers cubed . The electron density itself is easily computed from mass density and chemical composition of the material (cf. Sect. 2.2.1). 

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