1. 4.08 ± 0.02 nm
1.95 ± 0.68 nm
Alkanethiolate Bilayer Manipulation Using an Atomic force Microscope
Chad I. Drexler, Jevon K. Morris, Kevin B. Moore III, Corey P. Causey, Thomas J. Mullen
Department of Chemistry, University of North Florida, Jacksonville, FL 32224, tj.mullen@unf.edu
Fabrication of Alkanethiolate Mono- and Multilayer Films
Step 1 is completed by immersing the prepared substrate in a solution of the alkanethiol
molecules. The alkanethiolate monolayer generates spontaneously through interatomic
interactions between the sulfur and the metal surface. Further use of various iterations of step 2
& 3 allow for the production of multilayers ranging in thickness from a bilayer to multilayers.
The Mullen Group , Fall 2013
Acknowledgments
15 nN allowed for the selective removal of the
top layer of a bilayer. 80 nN allowed for the
selective to removal both layers.
Nanoshaving Multilayer Films of Varying Thicknesses
Nanoshaving was utilized to remove all the layers comprising multilayer
films. This allowed the film thickness to be corroborated.
Adjacent, chemically patterned, regions shaved at 15 nN and 80 nN allowed for
step size comparison of bilayer thickness.
We are grateful for support from UNF
Academic Affairs Faculty Development
Scholarship Grant and UNF startup
support.
Selective layer removal of a 16-mercaptohexadecanoic acid bilayer
Total displacement of 16-mercaptohexadecanoic acid multilayer films
Schematic depicting our chemical film assembly process
Principles of Atomic Force Microscopy
Gladys, The Mullen Lab Atomic
Force Microscope (AFM)
Atomic Force Microscopy (AFM) enables imaging of chemical surfaces with nanoscale
resolution. Additionally, the AFM may be employed to generate complex multifunctional
nanostructures using Scanning Probe lithographic techniques such as nanoshaving.
Au Substrate
Schematic of Atomic Force Microscope
Imaging of Preexistent Chemical Films
Topography of 16-Mercaptohexadecanoic Acid chemical films with specific thicknesses
1-2 nN of force allowed for topographical images of chemical films.
Introduction and Motivation
The manipulation of molecular structures is of interest in the design and manufacture of
chemical films. Alkanethiol molecules are often used in these films, due to their diverse
chemistries and ease of assembly upon metal surfaces. Most alkanethiol patterning
techniques are limited in their capabilities to produce multilayer chemical films because of
the inability of controlling the film’s thickness. One approach to control chemical film
thickness is utilizing the deposition of carboxylic acid terminated alkanethiol molecules and
copper ions. Employing this strategy, multilayer films were then characterized using Atomic
Force Microscopy (AFM) and by tailoring the force applied to the surface via the AFM tip,
we were able to remove the top layers and selectively form complex multifunctional patterns.
Schematic of different
shaving options for multilayer
patterning based on applied forces.
Determining Film Thickness Through Nanoshaving
Conclusions & Future Directions
In this work, the capability to generate complex multilayer chemical films has been
demonstrated, along with the implementation of nanoshaving to pattern these structures. In the
future, nanoshaving will be utilized to replicate the surface features of alkanethiolate structures
and to explore the capability of various polymeric molds. Thereby granting allowance for the
replication of complex multifunctional surface features with nanoscale precision.
Step 1
Step 3Step 2
Nanoshaving involves the application of high
force to a small area on a surface.
The applied force disrupts the
intermolecular interactions between sulfur and metal ions.
Selective Layer Removal and Chemical Patterning