Arrelaine A. Dameron

Scanning electron microscopy of nanoscale chemical patterns.

A series of nanoscale chemical patterning methods based on soft and hybrid nanolithographies have been characterized using scanning electron microscopy with corroborating evidence from scanning tunneling microscopy and lateral force microscopy. We demonstrate and discuss the unique advantages of the scanning electron microscope as an analytical tool to image chemical patterns of molecules highly diluted within a host self-assembled monolayer and to distinguish regions of differential mass coverage in patterned self-assembled monolayers. We show that the relative contrast of self-assembled monolayer patterns in scanning electron micrographs depends on the operating primary electron beam voltage, monolayer composition, and monolayer order, suggesting that secondary electron emission and scattering can be used to elucidate chemical patterns.

Enhanced molecular patterning via microdisplacement printing

Here we demonstrate the versatility of “microdisplacement printing,” a soft lithographic patterning technique that employs microcontact printing to replace pre-formed self-assembled monolayers (SAMs) selectively. We use molecules that are common in microcontact printing as well as low-molecular-weight molecules that cannot be patterned by traditional methods. Multiple component SAMs were fabricated by additional processing steps, extending microdisplacement printing to more complex patterns.

Measurements and Mechanisms of Single-Molecule Conductance Switching

We have engineered and analyzed oligo(phenylene-ethynylene) (OPE) derivatives to understand and to control the bistable conductance switching exhibited by these molecules when inserted into saturated alkanethiolate and amidecontaining alkanethiolate self-assembled monolayers (SAMs) on Au{111}. By engineering the structures of the OPE derivatives, we have shown conductance switching to depend on hybridization changes at the molecule–substrate interface. In addition, we have demonstrated bias-dependent switching controlled by interactions between the dipole of the OPEs and the electric field applied between the scanning tunneling microscope tip and the substrate. These interactions are stabilized via intermolecular hydrogen bonding between the OPEs and host amide-containing SAMs.