  Strain at surfaces and interfaces play an important role in the optical and
electronic properties of materials. MeV ion-induced strain determination in
single crystal silicon substrates and in Ag (nanoisland)/Si(111) at surface and
interfaces has been carried out using transmission electron microscopy (TEM)
and surface-sensitive X-ray diffraction. Ag nanoislands are grown under various
surface treatments using thermal evaporation in high vacuum conditions.
Irradiation has been carried out with 1.5 MeV Au^{2+} ions at various fluences
and impact angles. Selected area electron diffraction (SAED) and lattice
imaging (using TEM) has been used to determine the strain at surface and
interfaces. Preliminary results on the use of surface-sensitive asymmetric
x-ray Bragg reflection method have been discussed. The TEM results directly
indicate a contraction in the silicon lattice due to ion-induced effects. The
nanoislands have shadowed the ion beam resulting in lesser strain beneath the
island structures in silicon substrates. High-resolution lattice imaging has
also been used to determine the strain in around amorphization zones caused by
the ion irradiation.
