In-situ atomic force microscopy (AFM) imaging: influence of AFM probe geometry on diffusion to microscopic surfaces

Area of Science:

• Surface Science
• Electrochemistry
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) is crucial for nanoscale imaging.
• Understanding mass transport to reactive interfaces is key for electrochemical and crystal growth studies.
• The influence of AFM probe geometry on local diffusion has not been fully elucidated.

Purpose of the Study:

• To investigate how AFM probe geometry affects diffusion to micrometer-scale reactive electrode interfaces.
• To determine the invasiveness of different AFM probe types on mass transport.
• To provide guidelines for using in-situ AFM as a noninvasive probe for surface processes.

Main Methods:

• Utilized a disk-shaped substrate electrode held at a potential for diffusion-controlled reduction of aqueous Ru(NH3)6(3+).
• Measured current response during AFM imaging to assess local mass transport.
• Evaluated three probe types: V-shaped silicon nitride, single beam silicon, and batch-fabricated SECM-AFM probes.
• Employed 2D simulations to model AFM probe-surface interactions.

Main Results:

• Conventional V-shaped contact mode probes were found to be the most invasive to diffusion.
• Batch-fabricated scanning electrochemical-AFM (SECM-AFM) probes demonstrated the least invasive effect on diffusion.
• Probe parameters like cantilever size, tip cone height, and cone angle influence diffusion.

Conclusions:

• AFM probe geometry critically affects diffusion dynamics at reactive interfaces.
• SECM-AFM probes offer a less invasive approach for in-situ studies of mass transport.
• These findings are vital for accurately interpreting AFM data in electrochemical reactions, crystal growth, and dissolution studies.