Interactions of NH3 and O2 with the Surfaces of Chlorogallium Phthalocyanine Thin Films: Microcircuit Photoconductivity and Quartz-Crystal Microgravimetry Studies

S. Waite, J. Pankow, G. Collins, P. Lee, N. R. Armstrong

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

The chemisorption of O2 and NH3 on the surface of GaPc-Cl vacuum-deposited thin films has been studied by a combination of photoconductivity changes on interdigitated array microcircuits (MC) and mass uptake on quartz-crystal microbalances (QCM). Measurement of photoconductivity versus dark conductivity changes gives a higher sensitivity to changes caused by the adsorption of monolayer (or less) levels of these gases. The simultaneous monitoring of mass changes and photoconductivity changes shows clearly that there exists more than one type of chemisorption site for both O2 and NH3 and that these molecules compete for at least one of these sites. The response of the GaPc-Cl-coated microcircuit to NH3 in room temperature air is poor, because of this competition with O2. Photoelectrochemical modification (Ago deposition at submonolayer coverages) of the Pc-coated microcircuit is possible, however, which then provides for a reasonable room temperature response to NH3, presumably by producing a unique chemisorption site for this molecule.

Original languageEnglish (US)
Pages (from-to)797-805
Number of pages9
JournalLangmuir
Volume5
Issue number3
DOIs
StatePublished - May 1 1989

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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