Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 16 April 1993:
Vol. 260. no. 5106, pp. 323 - 326
DOI: 10.1126/science.260.5106.323
Prev | Table of Contents | Next

Articles

Structure of Langmuir-Blodgett Films of Disk-Shaped Molecules Determined by Atomic Force Microscopy

Jack Y. Josefowicz 1, Nicholas C. Maliszewskyj 2, Stefan H. J. Idziak 2, Paul A. Heiney 2, John P. McCauley Jr. 3, and Amos B. Smith III 3

1 Materials Science and Engineering Department and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104
2 Physics Department and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104
3 Chemistry Department and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, PA 19104

Monolayer Langmuir-Blodgett films of a discotic mesogen have been studied with atomic force microscopy (AFM). These measurements confirm the "edge on" arrangement for the disk-shaped molecules suggested by surface pressure—area isotherms and show that the molecules form columns that are separated by 17.7 angstroms ± 10 percent. Column alignment is found to be predominantly along the film deposition direction, with an angular spread of 35°. The AFM images also show that the mean disk separation within the columns is 5.1 ± 1.3 angstroms, in good agreement with x-ray diffraction (XRD) results. Roomtemperature XRD measurements on bulk samples of the same material indicate a disordered-hexagonal liquid crystalline mesophase, with a column-to-column spacing of 19.9 ± 0.2 angstroms.

Submitted on October 14, 1992
Accepted on January 13, 1993


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Two-Dimensional Melting of an Anisotropic Crystal Observed at the Molecular Level.
H. D. Sikes and D. K. Schwartz (1997)
Science 278, 1604-1607
   Abstract »    Full Text »
Liquid to hexatic to crystalline order in Langmuir-Blodgett films.
R Viswanathan, L. Madsen, J. Zasadzinski, and D. Schwartz (1995)
Science 269, 51-54
   Abstract »    PDF »
Controlling Molecular Order in "Hairy-Rod" Langmuir-Blodgett Films: A Polarization-Modulation Microscopy Study.
V. K. Gupta, J. A. Kornfield, A. Ferencz, and G. Wegner (1994)
Science 265, 940-942
   Abstract »    PDF »
Unexpected Square Symmetry Seen by Atomic Force Microscopy in Bilayer Films of Disk-Like Molecules.
N. C. Maliszewskyj, P. A. Heiney, J. Y. Josefowicz, J. P. McCauley Jr., and A. B. Smith III (1994)
Science 264, 77-79
   Abstract »    PDF »
Langmuir-Blodgett films.
J. Zasadzinski, R Viswanathan, L Madsen, J Garnaes, and D. Schwartz (1994)
Science 263, 1726-1733
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)