Chemical Phenomena of Atomic Force Microscopy Scanning

Area of Science:

• Materials Science
• Surface Chemistry
• Analytical Chemistry

Background:

• Atomic force microscopy (AFM) is a key technique for nanoscale material characterization.
• AFM tips are commonly assumed to be chemically inert during imaging.
• The chemical interactions at the tip-surface junction are not well understood.

Purpose of the Study:

• To investigate chemical processes at the tip-surface junction during AFM scanning.
• To determine if standard AFM procedures chemically alter material surfaces.
• To identify the source and extent of chemical contamination from AFM tips.

Main Methods:

• Utilized a hybrid system combining time-of-flight secondary ion mass spectrometry (ToF-SIMS) with AFM.
• Performed contact mode AFM scanning on material samples.
• Analyzed scanned regions for chemical modifications using ToF-SIMS.

Main Results:

• Basic contact mode AFM scanning significantly modifies material surfaces.
• Silicone oils from AFM tip storage containers were found in scanned areas.
• Contamination spread over distances exceeding 15 μm from the scanned tip path.

Conclusions:

• The chemical inertness of AFM tips is not universally applicable, even in basic scanning modes.
• Silicone oil contamination from tip storage affects nanoscale surface characterization.
• Results necessitate re-evaluation of AFM data, especially for mechanical and electrical studies.