Stability and superstructure of squarylium dye TSQ Langmuir–Blodgett films

The stability of monolayer Squarylium Dye TSQ in air-subphase interface was studied. Langmuir-Blodgett films of this dye were deposited on mica and on hydrophobic silicon (100) wafers and a contact mode atomic force microscope (AFM) was used to characterize the structures of these films. It was found that the stability of a TSQ monolayer in the air-subphase interface was increased substantially when cadmium chloride was added to the subphase. Although TSQ dye does not have a long alkyl tail typically required to form a LB film, AFM images of these films and their 2D Fourier Transform analyses show that TSQ LB films possess a triclinic superstructure. Based on the analyses of pressure-area (pi-A) isotherms and AFM images of these films, models of TSQ molecules packing on the subphase were developed. (C) 1998 Published by Elsevier Science S.A.