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Németh G, Bechtel HA, Borondics F. Origins and consequences of asymmetric nano-FTIR interferograms. OPTICS EXPRESS 2024; 32:15280-15294. [PMID: 38859183 DOI: 10.1364/oe.520793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 03/18/2024] [Indexed: 06/12/2024]
Abstract
Infrared scattering-type near-field optical microscopy, IR s-SNOM, and its broadband variant, nano-FTIR, are pioneering, flagship techniques for their ability to provide molecular identification and material optical property information at a spatial resolution well below the far-field diffraction limit, typically less than 25 nm. While s-SNOM and nano-FTIR instrumentation and data analysis have been discussed previously, there is a lack of information regarding experimental parameters for the practitioner, especially in the context of previously developed frameworks. Like conventional FTIR spectroscopy, the critical component of a nano-FTIR instrument is an interferometer. However, unlike FTIR spectroscopy, the resulting interference patterns or interferograms are typically asymmetric. Here, we unambiguously describe the origins of asymmetric interferograms recorded with nano-FTIR instruments, give a detailed analysis of potential artifacts, and recommend optimal instrument settings as well as data analysis parameters.
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de Oliveira R, Cadore AR, Freitas RO, Barcelos ID. Review on infrared nanospectroscopy of natural 2D phyllosilicates. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2023; 40:C157-C168. [PMID: 37132988 DOI: 10.1364/josaa.482518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Phyllosilicates have emerged as a promising class of large bandgap lamellar insulators. Their applications have been explored from the fabrication of graphene-based devices to 2D heterostructures based on transition metal dichalcogenides with enhanced optical and polaritonics properties. In this review, we provide an overview of the use of infrared (IR) scattering-type scanning near-field optical microscopy (s-SNOM) for studying nano-optics and local chemistry of a variety of 2D natural phyllosilicates. Finally, we bring a brief update on applications that combine natural lamellar minerals into multifunctional nanophotonic devices driven by electrical control.
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Xie Q, Xu XG. Fourier-Transform Atomic Force Microscope-Based Photothermal Infrared Spectroscopy with Broadband Source. NANO LETTERS 2022; 22:9174-9180. [PMID: 36368003 DOI: 10.1021/acs.nanolett.2c04097] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
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. A Fourier transform is performed to recover IR absorption spectra. We demonstrate the Fourier transform AFM-IR microscopy on a polymer blend and hexagonal boron nitride. An intriguing observation is the vertical asymmetry of the interferogram, which suggests the presence of multiphoton absorption processes under the tip-enhancement and femtosecond IR lasers. Our method demonstrates the feasibility of time-domain detection of the AFM-IR signal in the mid-IR regime and paves the way toward multiphoton vibrational spectroscopy at the nanoscale below the diffraction limit.
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Affiliation(s)
- Qing Xie
- Department of Chemistry, Lehigh University, 6 E Packer Avenue, Bethlehem, Pennsylvania18015, United States
| | - Xiaoji G Xu
- Department of Chemistry, Lehigh University, 6 E Packer Avenue, Bethlehem, Pennsylvania18015, United States
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4
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Broadband Near-Field Near-Infrared Spectroscopy and Imaging with a Laser-Driven Light Source. PHOTONICS 2022. [DOI: 10.3390/photonics9020097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
The scattering-type scanning near-field optical microscope (s-SNOM) has become a powerful imaging and nano-spectroscopy tool, which is widely used in the characterization of electronic and photonic devices, two-dimensional materials and biomolecules. However, in the published literature, nano-spectroscopy is mainly employed in the mid-infrared band, and the near-infrared (NIR) nano-spectroscopy with broadband spectral range has not been well discussed. In the present paper, we introduce a home-built near-field NIR spectroscopy and imaging set-up that is based on a laser-driven light source (LDLS). By mapping the Ge-Au periodic grating sample and the photonic topology device, a ~30 nm spatial resolution and the excellent capability of characterizing complex samples are demonstrated. Spectra obtained by experiment reveal the optical band-gap of Ge with a spectral resolution of 25 cm−1, and a spectral range from 900 to 2000 nm. This technology is expected to provide a novel and unique approach for near-field NIR spectroscopy and imaging.
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Chen X, Yao Z, Stanciu SG, Basov DN, Hillenbrand R, Liu M. Rapid simulations of hyperspectral near-field images of three-dimensional heterogeneous surfaces. OPTICS EXPRESS 2021; 29:39648-39668. [PMID: 34809324 DOI: 10.1364/oe.440821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/12/2021] [Indexed: 05/27/2023]
Abstract
The scattering-type scanning near-field optical microscope (s-SNOM) has emerged as a powerful tool for resolving nanoscale inhomogeneities in laterally heterogeneous samples. However, most analytical models used to predict the scattering near-field signals are assuming homogenous landscapes (bulk materials), resulting in inconsistencies when applied to samples with more complex configurations. In this work, we combine the point-dipole model (PDM) to the finite-element method (FEM) to account for the lateral and vertical heterogeneities while keeping the computation time manageable. Full images, spectra, or hyperspectral line profiles can be simulated by calculating the self-consistent dipole radiation demodulated at higher harmonics of the tip oscillation, mimicking real experimental procedures. Using this formalism, we clarify several important yet puzzling experimental observations in near-field images on samples with rich typography and complex material compositions, heterostructures of two-dimensional material flakes, and plasmonic antennas. The developed method serves as a basis for future investigations of nano-systems with nontrivial topography.
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Koroglu B, Dai Z, Finko M, Armstrong MR, Crowhurst JC, Curreli D, Weisz DG, Radousky HB, Knight KB, Rose TP. Experimental Investigation of Uranium Volatility during Vapor Condensation. Anal Chem 2020; 92:6437-6445. [PMID: 32233449 DOI: 10.1021/acs.analchem.9b05562] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The predictive models that describe the fate and transport of radioactive materials in the atmosphere following a nuclear incident (explosion or reactor accident) assume that uranium-bearing particulates would attain chemical equilibrium during vapor condensation. In this study, we show that kinetically driven processes in a system of rapidly decreasing temperature can result in substantial deviations from chemical equilibrium. This can cause uranium to condense out in oxidation states (e.g., UO3 vs UO2) that have different vapor pressures, significantly affecting uranium transport. To demonstrate this, we synthesized uranium oxide nanoparticles using a flow reactor under controlled conditions of temperature, pressure, and oxygen concentration. The atomized chemical reactants passing through an inductively coupled plasma cool from ∼5000 to 1000 K within milliseconds and form nanoparticles inside a flow reactor. The ex situ analysis of particulates by transmission electron microscopy revealed 2-10 nm crystallites of fcc-UO2 or α-UO3 depending on the amount of oxygen in the system. α-UO3 is the least thermodynamically preferred polymorph of UO3. The absence of stable uranium oxides with intermediate stoichiometries (e.g., U3O8) and sensitivity of the uranium oxidation states to local redox conditions highlight the importance of in situ measurements at high temperatures. Therefore, we developed a laser-based diagnostic to detect uranium oxide particles as they are formed inside the flow reactor. Our in situ measurements allowed us to quantify the changes in the number densities of the uranium oxide nanoparticles (e.g., UO3) as a function of oxygen gas concentration. Our results indicate that uranium can prefer to be in metastable crystal forms (i.e., α-UO3) that have higher vapor pressures than the refractory form (i.e., UO2) depending on the oxygen abundance in the surrounding environment. This demonstrates that the equilibrium processes may not dominate during rapid condensation processes, and thus kinetic models are required to fully describe uranium transport subsequent to nuclear incidents.
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Affiliation(s)
- Batikan Koroglu
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Zurong Dai
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Mikhail Finko
- Nuclear Plasma and Radiological Engineering, College of Engineering, University of Illinois at Urbana-Champagne, Urbana, Illinois 61801, United States
| | - Michael R Armstrong
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Jonathan C Crowhurst
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Davide Curreli
- Nuclear Plasma and Radiological Engineering, College of Engineering, University of Illinois at Urbana-Champagne, Urbana, Illinois 61801, United States
| | - David G Weisz
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Harry B Radousky
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Kim B Knight
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Timothy P Rose
- Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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Chen X, Hu D, Mescall R, You G, Basov DN, Dai Q, Liu M. Modern Scattering-Type Scanning Near-Field Optical Microscopy for Advanced Material Research. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1804774. [PMID: 30932221 DOI: 10.1002/adma.201804774] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 02/27/2019] [Indexed: 05/27/2023]
Abstract
Infrared and optical spectroscopy represents one of the most informative methods in advanced materials research. As an important branch of modern optical techniques that has blossomed in the past decade, scattering-type scanning near-field optical microscopy (s-SNOM) promises deterministic characterization of optical properties over a broad spectral range at the nanoscale. It allows ultrabroadband optical (0.5-3000 µm) nanoimaging, and nanospectroscopy with fine spatial (<10 nm), spectral (<1 cm-1 ), and temporal (<10 fs) resolution. The history of s-SNOM is briefly introduced and recent advances which broaden the horizons of this technique in novel material research are summarized. In particular, this includes the pioneering efforts to study the nanoscale electrodynamic properties of plasmonic metamaterials, strongly correlated quantum materials, and polaritonic systems at room or cryogenic temperatures. Technical details, theoretical modeling, and new experimental methods are also discussed extensively, aiming to identify clear technology trends and unsolved challenges in this exciting field of research.
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Affiliation(s)
- Xinzhong Chen
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Debo Hu
- Division of Nanophotonics, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Ryan Mescall
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Guanjun You
- Shanghai Key Lab of Modern Optical Systems and Engineering Research Center of Optical Instrument and System, Ministry of Education, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Qing Dai
- Division of Nanophotonics, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Mengkun Liu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
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Watts KE, Blackburn TJ, Pemberton JE. Optical Spectroscopy of Surfaces, Interfaces, and Thin Films: A Status Report. Anal Chem 2019; 91:4235-4265. [PMID: 30790520 DOI: 10.1021/acs.analchem.9b00735] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Kristen E Watts
- Department of Chemistry and Biochemistry University of Arizona 1306 East University Boulevard , Tucson , Arizona 85721 , United States
| | - Thomas J Blackburn
- Department of Chemistry and Biochemistry University of Arizona 1306 East University Boulevard , Tucson , Arizona 85721 , United States
| | - Jeanne E Pemberton
- Department of Chemistry and Biochemistry University of Arizona 1306 East University Boulevard , Tucson , Arizona 85721 , United States
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Affiliation(s)
- Lifu Xiao
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Zachary D Schultz
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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