Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer

Area of Science:

• Atomic Force Microscopy (AFM)
• Nanotechnology
• Materials Science

Background:

• Photothermal excitation is a key method for dynamic-mode AFM.
• Low excitation efficiency limits its practical applications.
• Improving efficiency is crucial for advanced AFM studies.

Purpose of the Study:

• To enhance photothermal excitation efficiency in AFM.
• To develop a stable and effective photothermal conversion (PTC) layer.
• To demonstrate the method's applicability in liquid environments.

Main Methods:

• Coating the backside of AFM cantilevers with colloidal graphite.
• Utilizing the colloidal graphite as a photothermal conversion (PTC) layer.
• Performing AFM measurements in liquid (phosphate buffer saline solution).

Main Results:

• Excitation efficiency improved 6.1 times for a standard cantilever (≈40 N/m).
• Efficiency improved 2.5 times for a stiff cantilever (≈140 N/m).
• Demonstrated stable, atomic-resolution AFM imaging in liquid for over 2 hours.

Conclusions:

• Colloidal graphite PTC layers significantly boost photothermal excitation efficiency.
• The method is effective even for stiff cantilevers in liquid.
• Enhanced photothermal excitation improves AFM stability, accuracy, and applicability.