McXtrace - An X-ray ray-trace simulation package

1.2  Symbols for x-ray scattering and simulation

In the description of the theory behind the component functionality we will use the usual symbols r for the position \((x,y,z)\) of the particle (unit m), and k for the particle wave vector \((k_x, k_y, k_z)\) (unit \(\mathrm {\bool_if:NF \g__siunitx_emulation_unit_warning_\angstrom_bool {\bool_gset_true:N \g__siunitx_emulation_unit_warning_\angstrom_bool \msg_warning:nnnn {siunitx}{unit-deprecated}{\angstrom}{\text {Å}}}\text {Å}}^{-1}\)). The wavelength is the reciprocal wave vector, \(\lambda =2 \pi / k\). By convention energy is usually given i \(\mathrm {keV}\) and may be calculated from the wavelength by: \(\lambda =\frac {12.398}{E}\)

In general, vectors are denoted by boldface symbols.

Subscripts ”i” and ”f” denotes “initial” and “final”, respectively, and are used in connection with the photon state before and after an interaction with the component in question.