Applications of PFIR 

We are actively seeking collaborations to apply PFIR microscopy. If you have a sample that requires nanoscale multimodal characterization, feel free to reach out to Dr. Xu. 

Aerosols of less than 2.5 microns (PM2.5)

Aerosols are tiny particles levitating in the air. Small aerosol particles (PM2.5, diameter < 2.5 microns) are difficult to be filtered out and can reach respiratory trait. Small aerosol particles also float in the air for many hours, even days. The main transmission route for COVID-19 pathogen is believed to be aerosols. 

The PFIR microscopy provides a route for both chemical and mechanical characterizations under ambient conditions.

Biological Cells

The PFIR microscopy can reveal the chemical compositions of micro- to nanoscale biological entities without extrinsic labels. The PFIR microscopy has been utilized to reveal the chemical composition of the bud scar of a zymosan particle from yeast. For more details, please see  Langmuir,  36, 6169 (2020)

Amyloid Fibrils

Amyloid fibrils are misfolded proteins. The secondary structures of proteins have indicative IR responses. The PFIR microscopy allows for mapping the amyloid fibrils at different IR frequencies that corresponds to different secondary structures   Proc. SPIE 11252,  (2020) DOI:10.1117/12.2541976 

Organic Matters in Oil Shale Source Rock

Oil shale source rock contains organic matters (kerogen) that can be utilized to obtain hydrocarbons. Kerogens are present in small nanoscale pores inside the source rock and are mixtures of different hydrocarbons, both saturated and unsaturated. The PFIR microscopy enables nanoscale mapping of the hydrocarbons of the source rock and reveal the maturation of the kerogens. Analytical Chemistry, 91, 14, 8883-8890 (2019)

Probing Phonon Polaritons in the Aqueous Phase

One potential utilization of polaritons (plasmons and phonon polaritons) is for chemical sensing. Many applicant scenarios of chemical sensing are in the fluid or aqueous phase. However, there was a deficiency in real space probing mid-infrared polaritons for nano- and microstructures in the aqueous phase. In 2020, we presented our approach to probing phonon polaritons in the aqueous phase with LiPFIR microscopy. The details of the work are described in Nano Letters, 20, 5, 3986-3991 (2020).

In situ aqueous phase measurement of click chemistry reactions

Click chemistry reactions are widely used in biochemical research. They operate under room temperature and aqueous phases. Our group has performed a demonstration of click chemistry reaction with LiPFIR

Other Applications of PFIR 

The PFIR microscopy and PFIR-type microscopy have been applied to other applications:

1. Characterization of attachment of proteins to substrate for immunology applications

2. Chemical identification of wood fibers

3. Revealing local heat generation from visible optical absorptions 

4. Phonon polaritons in hexagonal boron nitride 

5. Organic photovoltaic materials