Monitoring organic thin film growth in aqueous solution in-situ with a combined Quartz Crystal Microbalance and ellipsometry

A. Sarkar*, T. Viitala, T. Hofrnann, T. E. Tiwald, J. A. Woollam, A. Kjerstad, B. Laderian, M. Schubert

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedingConference contributionScientificpeer-review


Measuring thin films in aqueous environments poses a challenge because they may have an affinity for water (e.g. hydrogels) while adsorbed on a substrate. Typically, either the optical ellipsometry technique or the electromechanical Quartz Crystal Microbalance techniques are used to study thin films in-situ in aqueous environments. An ellipsometer measures the change in elliptically polarized light whereas the Quartz Crystal Microbalance utilizes the piezoelectric properties of an AT cut quartz crystal to measure properties of thin films. However, each technique has its limitations. The ellipsometer has the inherent limitation of coupling thickness of films of the order of a few nm with the film index of refraction. Commonly, the refractive index of the material is derived from ex-situ measurements performed on the bulk material. The Quartz Crystal Microbalance has the limitation that the density and the thickness of a film are coupled. Thus a reasonable assumption for the density must be made in order to determine the thickness. The ellipsometer can determine the actual amount of polymer present in a film. When measuring in-situ, an ellipsometer does not distinguish between water molecules attached to polymers comprising the film and the water in the ambient. However, the Quartz Crystal Microbalance measures the total mass attached to a substrate, i.e. both the polymer and the water molecules attached to it. Thus by combining the two instruments and correlating the thickness determined by each instrument, one can find the film porosity. We introduce a porosity parameter to characterize surfaces in aqueous environments. Our findings on formation of synperonic film on hydrophobic gold surface in aqueous environment are presented and discussed.

Original languageEnglish
Title of host publicationIn-Situ Studies Across Spatial and Temporal Scales for Nanoscience and Technology
PublisherMaterials Research Society
Number of pages7
ISBN (Print)9781615677726
Publication statusPublished - 2008
Externally publishedYes
MoE publication typeA4 Article in a conference publication
Event2008 MRS Fall Meeting - Boston, MA, United States
Duration: 1 Dec 20085 Dec 2008

Publication series

NameMaterials Research Society Symposium Proceedings
ISSN (Print)0272-9172


Conference2008 MRS Fall Meeting
Country/TerritoryUnited States
CityBoston, MA


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