Nanoscale infrared (nano-IR) microscopy enables label-free chemical imaging with a spatial resolution below Abbe's diffraction limit through the integration of atomic force microscopy and infrared radiation. Peak force infrared (PFIR) microscopy is one of the emerging nano-IR methods that provides non-destructive multimodal chemical and mechanical characterization capabilities using a straightforward photothermal signal generation mechanism. PFIR microscopy has been demonstrated to work for a wide range of heterogeneous samples, and it even allows operation in the fluid phase. However, the current PFIR microscope requires customized hardware configuration and software programming for real-time signal acquisition and processing, which creates a high barrier to PFIR implementation. In this communication, we describe a type of lock-in amplifier-based PFIR microscopy that can be assembled with generic, commercially available equipment without special hardware or software programming. We demonstrate this method on soft matters of structured polymer blends and blocks, as well as biological cells of . The lock-in amplifier-based PFIR reduces the entry barrier for PFIR microscopy and makes it a competitive nano-IR method for new users.
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http://dx.doi.org/10.1039/d2an01103d | DOI Listing |
J Phys Chem Lett
August 2024
School of Electronic Science and Engineering, Fujian Key Laboratory of Ultrafast Laser Technology and Applications, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
The microscopic structure of the material's solid-liquid interface significantly influences its physicochemical properties. Peak force infrared microscopy (PFIR) is a powerful technique for analyzing these interfaces at the nanoscale, revealing crucial structure-activity relationships. PFIR is recognized for its explicit photothermal signal generation mechanism but tends to overlook other photoinduced forces, which can disturb the obtained infrared spectra, thereby reducing spectral signal-to-noise ratio (SNR) and sensitivity.
View Article and Find Full Text PDFAnalyst
January 2023
Department of Chemistry, Lehigh University, 6 E Packer Ave., Bethlehem, PA, 18015, USA.
Nanoscale infrared (nano-IR) microscopy enables label-free chemical imaging with a spatial resolution below Abbe's diffraction limit through the integration of atomic force microscopy and infrared radiation. Peak force infrared (PFIR) microscopy is one of the emerging nano-IR methods that provides non-destructive multimodal chemical and mechanical characterization capabilities using a straightforward photothermal signal generation mechanism. PFIR microscopy has been demonstrated to work for a wide range of heterogeneous samples, and it even allows operation in the fluid phase.
View Article and Find Full Text PDFNano Lett
November 2022
Department of Chemistry, Lehigh University, 6 E Packer Avenue, Bethlehem, Pennsylvania18015, United States.
The mechanical detection of photothermal expansion from infrared (IR) absorption with an atomic force microscope (AFM) bypasses Abbe's diffraction limit, forming the chemical imaging technique of AFM-IR. Here, we develop a Fourier transform AFM-IR technique with peak force infrared microscopy and broadband femtosecond IR pulses. A Michelson interferometer creates a pair of IR pulses with controlled time delays to generate photothermal signals transduced by AFM to form an interferogram.
View Article and Find Full Text PDFChem Soc Rev
July 2022
Department of Chemistry, Lehigh University, Bethlehem, PA, 18015, USA.
Peak force infrared (PFIR) microscopy is an emerging atomic force microscopy (AFM)-based infrared microscopy that bypasses Abbe's diffraction limit on spatial resolution. The PFIR microscopy utilizes a nanoscopically sharp AFM tip to mechanically detect the tip-enhanced infrared photothermal response of the sample in the time domain. The time-gated mechanical signals of cantilever deflections transduce the infrared absorption of the sample, delivering infrared imaging and spectroscopy capability at sub 10 nm spatial resolution.
View Article and Find Full Text PDFAnal Chem
January 2022
Department of Chemistry, Lehigh University, 6 E. Packer Ave., Bethlehem, Pennsylvania 18015, United States.
Peak force infrared (PFIR) microscopy achieves nanoscale infrared imaging at sub-10 nm spatial resolution through photothermal mechanical detection of atomic force microscopy (AFM). However, it suffers from a major limitation that only one infrared frequency can be scanned for an AFM frame at a time. To overcome this limitation, we report here dual-color PFIR microscopy that enables simultaneous imaging at two infrared frequencies.
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