We have used Grazing Incidence X-ray Diffraction (GIXS) to study the struct
ure of a smectic A liquid crystal (LC) at the buried LC-glass interface in
liquid crystal films. This measurement is done in reflection mode through t
he glass substrate, which consists of a grating photolithographed onto a 0.
2 mm thick slide. The observed in-plane alignment indicates the presence of
tilted layers within 50 Angstrom of the glass interface, inside the groove
s. These layers correspond to the tilted region observed previously in samp
les confined within the grating grooves. The tilted layer region is suppres
sed by the grating induced homogeneously aligned LC layers, which act as a
new confining boundary that modifies the LC structure within the grooves. T
he interaction between the two observed in-plane regions depends on the thi
ckness of the LC films as well as the depth of the gratings' grooves.