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.

Urban aerosols 

Spectra within urban collected aerosol particle. Oxidization signature is observed, suggesting secondary organic aerosol origin.  Chemical Communications,  53, 7397 (2017) 

Indoor aerosols

Multimodal imaging of an indoor aerosol particle, revealing both protein and carbonyl signatures.  Analytical Chemistry, 93, 50, 16845-16852 (2021) 

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 

The scale bar is 100 nm.

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)

Perovskite Photovoltaic Materials

The PFIR microscopy can reveal chemical heterogeneity at the nanoscale, or verify the homogeneity of high quality materials. The perovskite photovoltaic materials often requires high surface uniformity at the nanoscale. The multimodal characterization capability of PFIR can be used to verify it. 

We helped our collaborator to characterized their high performance perovskite materials. Their work is presented in Science, 373, 6554, 561-567 (2021)

If you have a perovskite sample that needs PFIR characterization, you may contact us for collaboration. 

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).

Characteristic interference fringes of phonon polariton of h-BN are observed with liquid-phase PFIR microscopy

Dispersion relationship of phonon polaritons becomes different in the aqueous phase than in the air

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

Initiation of the click chemistry reaction in the liquid-phase PFIR chamber and track through nano-IR signatures in aqueous phase. For more details, please see our work Analytical Chemistry, 93, 7, 3567-3575  (2021)