2-D lattice constant control in lb films containing pyrrole

Pyrrole (Py) was used as a spacer molecule and we studied the structural phase transition of two-dimensional (2-D) crystal latti ce of the arachidic acid (C20) Langmuir-Blodgett films using atomic force microscopy. It was found that when quantity of Py in the Langmuir-Blodgett film is increased, the molecular occupation area of C20 molecules increased and that the crystal lattice changed as follows : “oblique → hexagonal → rectangular”. These structural phase transitions were compared with the computer simulation using 3-D model of the molecules by molecular mechanics.