Scanning probe studies of water nucleation on aluminum oxide and gold surfaces.
The nucleation of nanoscale water at surfaces in humid environments is sensitive to several factors, including the details of the surface morphology, ability of the surface to hydrate and the presence of contaminants. Tapping mode atomic force microscopy was used to investigate the nucleation process as a function of relative humidity (RH) on passive aluminum and gold thin films. Films exposed to the ambient environment prior to RH exposure showed discrete structures with lateral sizes ranging from 10 to 100 nm only at RH > 70%. These structures formed preferentially at grain boundaries, triple points and regions with significant topography such as protruding grains. The morphology of the passive aluminum surface is permanently altered at the sites where discrete structures were observed; nodules with heights ranging from 0.5 to 2 nm persist even after reducing the RH to <2%. The gold surface does not show such a permanent change in morphology after reducing the RH. Passive aluminum films exposed to high RH immediately after growth (e.g. no ambient exposure) do not show discrete structures even at the highest RH exposures of 90%, suggesting a hydrophilic surface and the importance of surface hydrocarbon contaminants in affecting the distribution of the water layer.
- Research Organization:
- Sandia National Laboratories
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 973653
- Report Number(s):
- SAND2005-4264J
- Journal Information:
- Proposed for publication in Applied Surface Science., Journal Name: Proposed for publication in Applied Surface Science. Journal Issue: 7 Vol. 254; ISSN ASUSEE; ISSN 0169-4332
- Country of Publication:
- United States
- Language:
- English
Similar Records
Influence of substrate topography on the nucleation of diamond thin films
Changes in optical transmittance of aluminum nitride thin films exposed to air