Atomic structure of the c(4 x 2) surface reconstruction of Ge(001) as determined by X-ray diffraction

The c(4 X 2) reconstruction of Ge(001) has been studied by x-ray diffraction of 150 K by measuring in-plane reflections and out-of-plane intensities of fractional order rods. The structure consists of an alternate arrangement of buckled dimers (tilt angle 19° • 1°) along the [110] and [110] surface directions. The dimer rows are not straight along the [110] direction but show a slight zigzag with an amplitude of 0.340 • 0.005 Å.