Revealing Phonon Polaritons in Hexagonal Boron Nitride by Multipulse Peak Force Infrared Microscopy

Wang, Le; Wagner, Martin; Wang, Haomin; Pau‐Sanchez, Siuling; Li, Jiahan; Edgar, James H.; Xu, Xiaoji G.

doi:10.1002/adom.201901084

“…Besides s-SNOM, AFM-based photothermal infrared microscopy has also revealed the PhPs in h-BN by detecting fringes. 5,[16][17][18] . However, no prior aqueous phase mid-infrared nano-imaging of PhPs in h-BN has been explored in the aqueous phase due to various challenges, from high light delivery loss to anharmonicity in cantilever oscillation in water.…”

Section: Resultsmentioning

confidence: 99%

“…Here, LiPFIR reveals the characteristic frequency-dependent interference fringes from hyperbolic phonon polaritons in 10 It combines the recently developed multipulse peak force infrared (PFIR) microscopy with total internal reflection beam delivery in the liquid phase. [12][13] The scheme of the apparatus of LiPFIR is illustrated in Figure 1a. A liquid-phase AFM (Bioscope Catalyst, Bruker) with a fluid chamber is operated under the peak force tapping mode at the peak force tapping (PFT) frequency of 1 kHz by an AFM controller (Nanoscope V, Bruker).…”

Section: Introductionmentioning

confidence: 99%

Probing Mid-Infrared Phonon Polaritons in the Aqueous Phase

Wang

¹

,

Janzen

²

,

Wang

³

et al. 2020

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Phonon polaritons (PhPs), the collective phonon oscillations with hybridized electromagnetic fields, concentrate optical fields in the mid-infrared frequency range that matches the vibrational modes of molecules. The utilization of PhPs holds the promise for chemical sensing tools and polariton-enhanced nanospectroscopy. However, investigations and innovations on PhPs in the aqueous phase remains stagnant, because of the lack of in situ mid-infrared nano-imaging methods in water. Strong infrared absorption from water prohibits optical delivery and detection in the mid-infrared for scattering-type nearfield microscopy. Here, we present our solution: the detection of photothermal responses caused by the excitation of PhPs by liquid phase peak force infrared (LiPFIR) microscopy. Characteristic interference fringes of PhPs in 10 B isotope-enriched h-BN were measured in the aqueous phase and their dispersion relationship extracted. LiPFIR enables the measurement of mid-infrared PhPs in the fluid phase, opening possibilities, and facilitating the development of mid-IR phonon polaritonics in water.

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“…is performed to remove the slow varying curvature of the cantilever deflection in Figure 1f to retrieve pure oscillations at the repetition frequency of the laser pulse ( Figure 1g). This procedure bypasses the self-reference scheme of the original PFIR microscopy, 6,23 and doubles the signal acquisition speed. The amplitude of the cantilever oscillations is extracted with a fast Fourier transform.…”

Section: Operational Principle and Design Of Lipfir Microscopymentioning

confidence: 99%

Liquid-Phase Peak Force Infrared Microscopy

Wang

¹

,

González-Fialkowski²,

Li³

et al. 2020

Preprint

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0

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Atomic force microscopy-infrared microscopy (AFM-IR) provides a route to bypass Abbe’s diffraction limit through photothermal detections of infrared absorption. With the combination of total internal reflection, AFM-IR can operate in the aqueous phase. However, AFM-IR in contact mode suffers from surface damage from the lateral shear force between the tip and sample, and can only achieve 20~25-nm spatial resolution. Here, we develop the liquid-phase peak force infrared (LiPFIR) microscopy that avoids the detrimental shear force and delivers an 8-nm spatial resolution. The non-destructiveness of the LiPFIR microscopy enables <i>in situ</i> chemical measurement of heterogeneous materials and investigations on a range of chemical and physical transformations, including polymer surface reorganization, hydrogen-deuterium isotope exchange, and ethanol-induced denaturation of proteins. We also perform LiPFIR imaging of the budding site of yeast cell wall in the fluid as a demonstration of biological applications. LiPFIR unleashes the potential of in liquid AFM-IR for chemical nanoscopy.

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“…A polynomial fit is performed to remove the slow varying curvature of the cantilever deflections in Figure 1f to retrieve cantilever oscillations at the laser repetition rate shown in Figure 1g. The procedure bypasses the self-reference scheme of the standard PFIR microscopy, 4,23 and doubles the signal acquisition speed. The amplitude of the cantilever oscillations is extracted with a fast Fourier transform.…”

Section: Operational Principle and Design Of Lipfir Microscopymentioning

confidence: 99%

Liquid-Phase Peak Force Infrared Microscopy for Chemical Nano-imaging and Spectroscopy of Soft Matters

Wang

¹

,

González-Fialkowski²,

Li³

et al. 2020

Preprint

Self Cite

1

0

View full text Add to dashboard Cite

Atomic force microscopy-infrared microscopy (AFM-IR) provides a route to bypass Abbe’s diffraction limit through photothermal detections of infrared absorption. With the combination of total internal reflection, AFM-IR can operate in the aqueous phase. However, AFM-IR in contact mode suffers from surface damage from the lateral shear force between the tip and sample, and can only achieve 20~25-nm spatial resolution. Here, we develop the liquid-phase peak force infrared (LiPFIR) microscopy that avoids the detrimental shear force and delivers an 8-nm spatial resolution. The non-destructiveness of the LiPFIR microscopy enables <i>in situ</i> chemical measurement of heterogeneous materials and investigations on a range of chemical and physical transformations, including polymer surface reorganization, hydrogen-deuterium isotope exchange, and ethanol-induced denaturation of proteins. We also perform LiPFIR imaging of the budding site of yeast cell wall in the fluid as a demonstration of biological applications. LiPFIR unleashes the potential of in liquid AFM-IR for chemical nanoscopy.

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Revealing Phonon Polaritons in Hexagonal Boron Nitride by Multipulse Peak Force Infrared Microscopy

Cited by 20 publications

References 36 publications

Probing Mid-Infrared Phonon Polaritons in the Aqueous Phase

Probing Mid-Infrared Phonon Polaritons in the Aqueous Phase

Liquid-Phase Peak Force Infrared Microscopy

Liquid-Phase Peak Force Infrared Microscopy for Chemical Nano-imaging and Spectroscopy of Soft Matters

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