Imaging deoxyribose nucleic acid molecules on a metal surface under water by scanning tunneling microscopy

Stuart Lindsay, B. Barris

Research output: Contribution to journalArticle

78 Scopus citations

Abstract

We have investigated the mechanism of a scanning tunneling microscope operated in air and water by measuring current-distance (It~s) characteristics and making spatial maps of dlt /ds, for Pt and W tips and gold substrates. Although the It-s curves are characteristic of tunneling, their interpretation in terms of work functions would require values between a few tenths of and a few thousandths of the vacuum values. These values do not depend on the metals or the tunneling medium. We conclude that the tip and substrate are always in contact via an insulating adsorbate layer. We prepare flat, clean gold surfaces onto which we can form stable aggregates of DNA molecules under a buffer solution in a small electrochemical cell by a cycle of plating followed by stripping. The aggregates are imaged both as depressions in a constant-current topology map, and dramatic changes on a dlt /ds map. 20-A corrugations are clearly visible in dense aggregates of high molecular weight DNA which appear to pack with liquid-crystalline order. On occasion the path of an individual molecule can be followed.

Original languageEnglish (US)
Pages (from-to)544-547
Number of pages4
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume6
Issue number2
DOIs
StatePublished - 1988

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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