The equation (2) is nothing else but specimen shift in the Bragg-Brentano
geometry.
> I have a question concerning the systematic line shifts due to sample
> off-centering in the Debye-Scherrer-geometry. The shift D2Theta due to an
> eccentricity e in the incident beam direction is always given as
> (1) D2Theta = (e/R)*sin(2*Theta)
> with R being the radius of the goniometer circle. For the shift caused by
> an eccentricity normal to the incident beam direction it is given in the
> literature and used in refinement programms as
>
> (2) D2Theta = (e/R)*cos(Theta)
>
> When I tried to comprehend this equations I had no problems with (1), but
> for the eccentricity normal to the incident beam direction I always got
>
> D2Theta = (e/R)*cos(2*Theta)
>
> instead of (2). So, does anybody here in the list know the article in
> which the development of (2) is described?
>
>
> Daniel Toebbens
>
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