We report on ellipsometric measurements on freely suspended liquid-cry
stal films of two compounds possessing smectic-A and ferroelectric sme
ctic-C phases. One of the compounds shows in addition an antiferroelec
tric smectic-C-A phase. The comparison of the surface-induced order ne
ar the smectic-A to smectic-C transition indicates that the latter com
pound shows a considerably reduced coupling of the molecular tilt in n
eighbouring layers possessing the same tilt directions.