Q value

A given q value (momentum transfer in reciprocal-space) corresponds to a real-space distance (d) of:

$q={\frac {2\pi }{d}}$

Thus, from a peak position in scattering, one can calculate the realspace repeat-structure distance:

$d={\frac {2\pi }{q}}$

One must be careful, however. A peak in reciprocal-space corresponds to a repeating structure in the realspace lattice; i.e. this may or may not correspond directly to particle-particle spacings.