Progress in near-field photothermal infra-red microspectroscopy

Area of Science:

• Spectroscopy
• Microscopy
• Nanotechnology

Background:

• Developing techniques for sub-diffraction limit spatial resolution is crucial in analytical sciences.
• Near-field optical techniques combined with atomic force microscopy (AFM) offer potential for high-resolution imaging and spectroscopy.
• Infra-red microspectroscopy provides valuable chemical information but is often limited by diffraction.

Purpose of the Study:

• To introduce a new implementation of near-field photothermal Fourier transform infra-red microspectroscopy.
• To assess the sensitivity of this technique for analyzing small quantities of analytes and thin films.
• To explore a photothermomechanical approach using conventional AFM probes as an alternative sensing method.

Main Methods:

• Utilized near-field photothermal Fourier transform infra-red microspectroscopy with AFM-type temperature sensors.
• Recorded infra-red spectra from minute amounts of target materials to evaluate sensitivity.
• Investigated a photothermomechanical approach employing standard AFM probes for preliminary comparison.

Main Results:

• Successfully implemented a new configuration of near-field photothermal infra-red microspectroscopy.
• Demonstrated the technique's capability to record infra-red spectra from small analytes and thin films.
• Preliminary results indicate superior sensitivity of the photothermal approach over the thermomechanical method.

Conclusions:

• The developed near-field photothermal infra-red microspectroscopy technique shows promise for achieving spatial resolution beyond the diffraction limit.
• The photothermal sensing mechanism appears more sensitive for analyzing trace amounts of materials compared to the photothermomechanical approach.
• This advancement opens avenues for high-resolution chemical analysis of nanoscale samples.