X-ray diffraction was employed to study the structure of the Ag/Si(111
) interface. Samples were prepared by vacuum deposition of Ag onto Si(
111)-(7 x 7) followed by either annealing to 400 degrees C or no annea
l. The annealed and unannealed samples show significantly different Si
-substrate truncation-rod intensity profiles. The results are explaine
d in terms of structural features of the (7 x 7) reconstruction for th
e unannealed sample and a fairly abrupt (1 x 1) interface for the anne
aled sample.