AMBIENT ATOMIC-FORCE MICROSCOPY IMAGES OF STILBITE AND THEIR INTERPRETATION BY MOLECULAR SIMULATIONS

Atomic level AFM images of a cleaved (010) surface of stilbite, a natu ral zeolite, were obtained under ambient conditions. Two types of imag es were observed: one showing a surface which is close to bulk termina tion and the other showing a different atomic arrangement. The former gave surface lattice constants close to those of the bulk but within t he surface unit cell the atomic arrangements differ from what is expec ted for the (010) surface, The latter showed periodicity in c directio n 1.5 times that of bulk. Using a recently developed AFM simulator bas ed on a molecular simulation technique, the bulk-terminated surface im age was interpreted as the image of a surface partially covered with a dsorbate. Reasons for the appearance of the nonbulk-terminated surface are examined. (C) 1997 Elsevier Science B.V.