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Generalized Heterodyne Configurations for Photoinduced Force Microscopy
Le Wang1, Devon S Jakob1, Haomin Wang1
1Department of Chemistry , Lehigh University , 6 East Packer Avenue , Bethlehem , Pennsylvania 18015 , United States.
Analytical Chemistry
|September 24, 2019
Summary
Researchers have advanced photoinduced force microscopy (PiFM) by introducing two new heterodyne configurations. These methods enable nanoscale chemical imaging and broadband spectroscopy with enhanced flexibility and signal extraction capabilities.
Area of Science:
- Chemical Microscopy
- Nanotechnology
- Spectroscopy
Background:
- Atomic Force Microscopy (AFM) based infrared chemical microscopy bypasses the diffraction limit.
- Photoinduced Force Microscopy (PiFM) is a popular technique using mechanical heterodyne detection for light-matter interactions.
- Current PiFM implementations are limited to a single heterodyne configuration.
Purpose of the Study:
- To generalize heterodyne configurations for PiFM.
- To introduce harmonic heterodyne detection and sequential heterodyne detection schemes.
- To enhance chemical imaging and broadband spectroscopy capabilities at the nanoscale.
Main Methods:
- Developed harmonic heterodyne detection where laser repetition rate matches fractions of the difference between two AFM cantilever resonant modes.
- Introduced sequential heterodyne detection using laser pulse repetition rate and polarization modulation frequency.
- Utilized mechanical heterodyne signal detection between cantilever oscillations and photoinduced force.
Main Results:
- Successfully generalized PiFM with two novel heterodyne configurations.
- Achieved chemical imaging and broadband spectroscopy at approximately 10 nm spatial resolution.
- Demonstrated applicability to diverse materials including polymer films, boron nitride, and bacterial cell walls.
Conclusions:
- The generalized heterodyne configurations offer increased flexibility for PiFM implementation.
- These new schemes provide possibilities for targeted signal extraction via an additional modulation channel.
- The advancements open new avenues for nanoscale chemical analysis across various scientific disciplines.
