Chemically selective force mapping of electrochemically generated two-component ω-substituted alkanethiol monolayer gradients by pulsed-force-mode atomic force microscopy

Karin M. Balss, Glenn Allen Fried, Paul W. Bohn

Research output: Contribution to journalArticlepeer-review

Abstract

Pulsed-force-mode atomic force microscopy (PFM-AFM) was used to map the adhesion force between an AFM tip and samples prepared by microcontact printing (μCP) and electrochemically generated ω-substituted alkanethiol monolayer gradients. AFM tips chemically derivatized to terminate with either -CH3 or -COOH end functional groups were used to measure the adhesion force difference between CH3- and COOH-terminated regions on a μCP sample in both air and deionized H2O. Images acquired in air with a CH3-terminated tip yielded mean adhesion force differences between CH3- and COOH-terminated sample regions, |ΔF|, of 7.5 ± 4.8 nN for tips prepared from alkanethiols on Au and 11.1 ± 3.0 nN for tips prepared from alkylsiloxanes on Si. The variability in |ΔF| was significantly reduced in deionized H2O. PFM-AFM was also able to distinguish CH3- and COOH-terminated regions in an electrochemically generated gradient in air and deionized H2O. The contrast of the image and adhesion force differences measured on electrochemically generated gradients in H2O were comparable to those measured on μCP samples. PFM-AFM images of electrochemically generated gradients indicated a transition region ∼75 mV wide in rough correspondence to the 60 mV width of the Fermi-Dirac distribution at 300 K.

Original languageEnglish (US)
JournalJournal of the Electrochemical Society
Volume149
Issue number9
DOIs
StatePublished - Sep 1 2002

ASJC Scopus subject areas

  • Electrochemistry
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

Fingerprint Dive into the research topics of 'Chemically selective force mapping of electrochemically generated two-component ω-substituted alkanethiol monolayer gradients by pulsed-force-mode atomic force microscopy'. Together they form a unique fingerprint.

Cite this