Sensing Molecular Adsorption Through Interfacial Electron Scattering in Atom -Scale Junctions
type: CreativeWork
description: The goal of this work was to fabricate Au atom-scale junctions as the basis for robust, regenerable, nanostructured sensors to use with mass-limited samples for improved protection of health and safety. Atom-scale junctions were formed between two Au thin film electrodes. The inter-electrode gap was lithographically defined, and a microfluidic channel was aligned over the inter-electrode gap. The inter-electrode gap was reduced with electrodeposition, which was terminated at an atom-scale junction by setting a comparator to trigger a relay at a current corresponding to a junction conductance comparable to the conductance quantum. Based on conductance measurements and estimates from SEM images, atom-scale junctions were successfully formed. Lewis bases were introduced to atom-scale junctions, and the resulting alternating current impedance change was measured. For example, the interfacial scattering from chemisorption of 10 mM hexadecanethiol (HDT) on a 2.6 G0 atom-scale junction caused a normalized impedance change of 71% +/- 1%, with a noise level consistent with a population fluctuation of only 1 HDT molecule. To regenerate the device in situ, the junction was broken with a potential sweep and reformed with comparator-terminated electrodeposition. The atom-scale junction capability to measure small numbers of adsorption/desorption events makes a powerful case for pushing the limits of sensitivity for electrical measurements of single molecule events.
abstract: The goal of this work was to fabricate Au atom-scale junctions as the basis for robust, regenerable, nanostructured sensors to use with mass-limited samples for improved protection of health and safety. Atom-scale junctions were formed between two Au thin film electrodes. The inter-electrode gap was lithographically defined, and a microfluidic channel was aligned over the inter-electrode gap. The inter-electrode gap was reduced with electrodeposition, which was terminated at an atom-scale junction by setting a comparator to trigger a relay at a current corresponding to a junction conductance comparable to the conductance quantum. Based on conductance measurements and estimates from SEM images, atom-scale junctions were successfully formed. Lewis bases were introduced to atom-scale junctions, and the resulting alternating current impedance change was measured. For example, the interfacial scattering from chemisorption of 10 mM hexadecanethiol (HDT) on a 2.6 G0 atom-scale junction caused a normalized impedance change of 71% +/- 1%, with a noise level consistent with a population fluctuation of only 1 HDT molecule. To regenerate the device in situ, the junction was broken with a potential sweep and reformed with comparator-terminated electrodeposition. The atom-scale junction capability to measure small numbers of adsorption/desorption events makes a powerful case for pushing the limits of sensitivity for electrical measurements of single molecule events.
author: Castle, Patrick James
language: eng
keywords: Chemistry, Analytical
date published: 2015-09-25T22:13:21Z
date modified: 2026-07-22T22:26:22Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/84182