The atomic structure of the {111} diamond face after oxygen-water-vapor etc
hing is determined using x-ray scattering. We find that a single dangling b
ond diamond {111} surface model, terminated by a full monolayer of -OH fits
our data best. To explain the measurements it is necessary to add an order
ed water layer on top of the -OH terminated surface. The vertical contracti
on of the surface cell and the distance between the oxygen atoms are genera
lly in agreement with model calculations and results on similar systems. Th
e OH termination is likely to be present during etching as well. This model
experimentally confirms the atomic-scale mechanism we proposed previously
for this etching system.