Forming microstructured alkanethiol self-assembled monolayers on gold by laser ablation

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Alkanethiols spontaneously form homogeneous self-assembled monolayers (SAMs) on gold surfaces.
• Creating microstructured SAMs is crucial for advanced surface engineering and device fabrication.
• Existing methods for SAM patterning can be complex or lack precision.

Purpose of the Study:

• To develop a reliable and easy method for creating microstructured alkanethiol SAMs on gold.
• To demonstrate the precise patterning capabilities of laser ablation for SAMs.
• To enable further functionalization of patterned SAM surfaces.

Main Methods:

• Utilized laser ablation with a frequency-doubled Nd:YVO4 laser (6-ns pulsewidth, 20-kHz repetition rate) at specific pulse intensities (120 MW/cm² ± 10%).
• Ablated exposed areas of alkanethiol monolayers on gold surfaces.
• Re-exposed gold surfaces were functionalized with second and third thiols to create patterned structures.
• Examined patterned structures using optical microscopy, fluorescence microscopy, and lateral force microscopy.

Main Results:

• Achieved reliable and easy formation of microstructured alkanethiol SAMs.
• Demonstrated laser ablation of alkanethiol monolayers without damaging the gold substrate.
• Created lines as narrow as 10 micrometers, filled with thiols of opposite hydrophilicity.
• Successfully patterned both hydrophilic and hydrophobic alkanethiol SAMs.

Conclusions:

• The laser ablation technique provides a robust method for preparing microstructured SAMs on gold.
• This technique offers precise control over surface patterning at the microscale.
• The method is potentially applicable to a wide range of substrates beyond gold.