1
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Rathbone E, Fu D. Quantitative Optical Imaging of Oxygen in Brain Vasculature. J Phys Chem B 2024; 128:6975-6989. [PMID: 38991095 DOI: 10.1021/acs.jpcb.4c01277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The intimate relationship between neuronal activity and cerebral oxygenation underpins fundamental brain functions like cognition, sensation, and motor control. Optical imaging offers a noninvasive approach to assess brain oxygenation and often serves as an indirect proxy for neuronal activity. However, deciphering neurovascular coupling─the intricate interplay between neuronal activity, blood flow, and oxygen delivery─necessitates independent, high spatial resolution, and high temporal resolution measurements of both microvasculature oxygenation and neuronal activation. This Perspective examines the established optical techniques employed for brain oxygen imaging, specifically functional near-infrared spectroscopy, photoacoustic imaging, optical coherence tomography, and two-photon phosphorescent lifetime microscopy, highlighting their fundamental principles, strengths, and limitations. Several other emerging optical techniques are also introduced. Finally, we discuss key technological challenges and future directions for quantitative optical oxygen imaging, paving the way for a deeper understanding of oxygen metabolism in the brain.
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Affiliation(s)
- Emily Rathbone
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Dan Fu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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2
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Thiebes JJ, Grumstrup EM. Quantifying noise effects in optical measures of excited state transport. J Chem Phys 2024; 160:124201. [PMID: 38516971 DOI: 10.1063/5.0190347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 03/03/2024] [Indexed: 03/23/2024] Open
Abstract
Time-resolved microscopy is a widely used approach for imaging and quantifying charge and energy transport in functional materials. While it is generally recognized that resolving small diffusion lengths is limited by measurement noise, the impacts of noise have not been systematically assessed or quantified. This article reports modeling efforts to elucidate the impact of noise on optical probes of transport. Excited state population distributions, modeled as Gaussians with additive white noise typical of experimental conditions, are subject to decay and diffusive evolution. Using a conventional composite least-squares fitting algorithm, the resulting diffusion constant estimates are compared with the model input parameter. The results show that heteroscedasticity (i.e., time-varying noise levels), insufficient spatial and/or temporal resolution, and small diffusion lengths relative to the magnitude of noise lead to a surprising degree of imprecision under moderate experimental parameters. Moreover, the compounding influence of low initial contrast and small diffusion length leads to systematic overestimation of diffusion coefficients. Each of these issues is quantitatively analyzed herein, and experimental approaches to mitigate them are proposed. General guidelines for experimentalists to rapidly assess measurement precision are provided, as is an open-source tool for customizable evaluation of noise effects on time-resolved microscopy transport measurements.
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Affiliation(s)
- Joseph J Thiebes
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
| | - Erik M Grumstrup
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
- Montana Materials Science Program, Montana State University, Bozeman, Montana 59717, USA
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3
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Katayama K. Pattern-illumination time-resolved phase microscopy and its applications for photocatalytic and photovoltaic materials. Phys Chem Chem Phys 2024; 26:9783-9815. [PMID: 38497609 DOI: 10.1039/d3cp06211b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Pattern-illumination time-resolved phase microscopy (PI-PM) is a technique used to study the microscopic charge carrier dynamics in photocatalytic and photovoltaic materials. The method involves illuminating a sample with a pump light pattern, which generates charge carriers and they decay subsequently due to trapping, recombination, and transfer processes. The distribution of photo-excited charge carriers is observed through refractive index changes using phase-contrast imaging. In the PI-PM method, the sensitivity of the refractive index change is enhanced by adjusting the focus position, the method takes advantage of photo-excited charge carriers to observe non-radiative processes, such as charge diffusion, trapping in defect/surface states, and interfacial charge transfer of photocatalytic and photovoltaic reactions. The quality of the image sequence is recovered using various informatics calculations. Categorizing and mapping different types of charge carriers based on their response profiles using clustering analysis provides spatial information on charge carrier types and the identification of local sites for efficient and inefficient photo-induced reactions, providing valuable information for the design and optimization of photocatalytic materials such as the cocatalyst effect.
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Affiliation(s)
- Kenji Katayama
- Department of Applied Chemistry, Chuo University, Tokyo 112-8551, Japan.
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4
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Brinatti Vazquez GD, Lo Gerfo Morganti G, Vasilev C, Hunter CN, van Hulst NF. Structured Excitation Energy Transfer: Tracking Exciton Diffusion below Sunlight Intensity. ACS PHOTONICS 2024; 11:1318-1326. [PMID: 38523751 PMCID: PMC10958594 DOI: 10.1021/acsphotonics.4c00004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 02/09/2024] [Accepted: 02/12/2024] [Indexed: 03/26/2024]
Abstract
With the increasing demand for new materials for light-harvesting applications, spatiotemporal microscopy techniques are receiving increasing attention as they allow direct observation of the nanoscale diffusion of excitons. However, the use of pulsed and tightly focused laser beams generates light intensities far above those expected under sunlight illumination, leading to photodamage and nonlinear effects that seriously limit the accuracy and applicability of these techniques, especially in biological or atomically thin materials. In this work, we present a novel spatiotemporal microscopy technique that exploits structured excitation in order to dramatically decrease the excitation intensity, up to 10,000-fold when compared with previously reported spatiotemporal photoluminescence microscopy experiments. We tested our method in two different systems, reporting the first exciton diffusion measurement at illumination conditions below sunlight, both considering average power and peak exciton densities in an organic photovoltaic sample (Y6), where we tracked the excitons for up to five recombination lifetimes. Next, nanometer-scale energy transport was directly observed for the first time in both space and time in a printed monolayer of the light-harvesting complex 2 from purple bacteria.
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Affiliation(s)
- Guillermo D. Brinatti Vazquez
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Giulia Lo Gerfo Morganti
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Cvetelin Vasilev
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K.
| | - C. Neil Hunter
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K.
| | - Niek F. van Hulst
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
- ICREA-Institució
Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, Barcelona 08010, Spain
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5
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Wu S, Chu W, Lu Y, Ji M. Imaging Ultrafast Dynamics of Pressure-Driven Phase Transitions in Black Phosphorus and Anomalous Coherent Phonon Softening. NANO LETTERS 2024; 24:424-432. [PMID: 38153402 DOI: 10.1021/acs.nanolett.3c04218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Applying high pressure to effectively modulate the electronic and lattice structures of materials could unravel various physical properties associated with phase transitions. In this work, high-pressure-compatible femtosecond pump-probe microscopy was constructed to study the pressure-dependent ultrafast dynamics in black phosphorus (BP) thin films. We observed pressure-driven evolution of the electronic topological transition and three structural phases as the pressure reached ∼22 GPa, which could be clearly differentiated in the transient absorption images containing spatially resolved ultrafast carrier and coherent phonon dynamics. Surprisingly, an anomalous coherent acoustic phonon mode with pressure softening behavior was observed within the range of ∼3-8 GPa, showing distinct laser power and time dependences. Density functional theory calculations show that this mode, identified as the shear mode along the armchair orientation, gains significant electron-phonon coupling strength from out-of-plane compression that leads to decreased phonon frequency. Our results provide insights into the structure evolution of BP with pressure and hold potential for applications in microelectromechanical devices.
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Affiliation(s)
- Simin Wu
- State Key Laboratory of Surface Physics and Department of Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Shanghai Key Laboratory of Metasurfaces for Light Manipulation, Fudan University, Shanghai 200433, China
| | - Weibin Chu
- State Key Laboratory of Surface Physics and Department of Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Shanghai Key Laboratory of Metasurfaces for Light Manipulation, Fudan University, Shanghai 200433, China
- Key Laboratory of Computational Physical Science (MOE) and Institute of Computational Physical Science, Fudan University, Shanghai 200433, China
| | - Yang Lu
- Center for High Pressure Science & Technology Advanced Research, Shanghai 201203, China
- Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree), Shanghai Advanced Research in Physical Sciences (SHARPS), Shanghai 201203, China
| | - Minbiao Ji
- State Key Laboratory of Surface Physics and Department of Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Shanghai Key Laboratory of Metasurfaces for Light Manipulation, Fudan University, Shanghai 200433, China
- Academy for Engineering and Technology, Yiwu Research Institute of Fudan University, Fudan University, Shanghai 200433, China
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6
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Gross N, Kuhs CT, Ostovar B, Chiang WY, Wilson KS, Volek TS, Faitz ZM, Carlin CC, Dionne JA, Zanni MT, Gruebele M, Roberts ST, Link S, Landes CF. Progress and Prospects in Optical Ultrafast Microscopy in the Visible Spectral Region: Transient Absorption and Two-Dimensional Microscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:14557-14586. [PMID: 37554548 PMCID: PMC10406104 DOI: 10.1021/acs.jpcc.3c02091] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/24/2023] [Indexed: 08/10/2023]
Abstract
Ultrafast optical microscopy, generally employed by incorporating ultrafast laser pulses into microscopes, can provide spatially resolved mechanistic insight into scientific problems ranging from hot carrier dynamics to biological imaging. This Review discusses the progress in different ultrafast microscopy techniques, with a focus on transient absorption and two-dimensional microscopy. We review the underlying principles of these techniques and discuss their respective advantages and applicability to different scientific questions. We also examine in detail how instrument parameters such as sensitivity, laser power, and temporal and spatial resolution must be addressed. Finally, we comment on future developments and emerging opportunities in the field of ultrafast microscopy.
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Affiliation(s)
- Niklas Gross
- Department
of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Christopher T. Kuhs
- Army
Research Laboratory-South, U.S. Army DEVCOM, Houston, Texas 77005, United States
| | - Behnaz Ostovar
- Department
of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Wei-Yi Chiang
- Department
of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Kelly S. Wilson
- Department
of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Tanner S. Volek
- Department
of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Zachary M. Faitz
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Claire C. Carlin
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - Jennifer A. Dionne
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
- Department
of Radiology, Molecular Imaging Program at Stanford (MIPS), Stanford University School of Medicine, Stanford, California 94305, United States
| | - Martin T. Zanni
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Martin Gruebele
- Department
of Chemistry, University of Illinois at
Urbana−Champaign, Urbana, Illinois 61801, United States
- Department
of Physics, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Center
for Biophysics and Quantitative Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Sean T. Roberts
- Department
of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Stephan Link
- Department
of Chemistry, Rice University, Houston, Texas 77005, United States
- Department
of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Christy F. Landes
- Department
of Chemistry, Rice University, Houston, Texas 77005, United States
- Department
of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Department
of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
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7
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Clark MG, Ma S, Mahapatra S, Mohn KJ, Zhang C. Chemical-imaging-guided optical manipulation of biomolecules. Front Chem 2023; 11:1198670. [PMID: 37214479 PMCID: PMC10196011 DOI: 10.3389/fchem.2023.1198670] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 04/20/2023] [Indexed: 05/24/2023] Open
Abstract
Chemical imaging via advanced optical microscopy technologies has revealed remarkable details of biomolecules in living specimens. However, the ways to control chemical processes in biological samples remain preliminary. The lack of appropriate methods to spatially regulate chemical reactions in live cells in real-time prevents investigation of site-specific molecular behaviors and biological functions. Chemical- and site-specific control of biomolecules requires the detection of chemicals with high specificity and spatially precise modulation of chemical reactions. Laser-scanning optical microscopes offer great platforms for high-speed chemical detection. A closed-loop feedback control system, when paired with a laser scanning microscope, allows real-time precision opto-control (RPOC) of chemical processes for dynamic molecular targets in live cells. In this perspective, we briefly review recent advancements in chemical imaging based on laser scanning microscopy, summarize methods developed for precise optical manipulation, and highlight a recently developed RPOC technology. Furthermore, we discuss future directions of precision opto-control of biomolecules.
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Affiliation(s)
| | - Seohee Ma
- Department of Chemistry, West Lafayette, IN, United States
| | | | | | - Chi Zhang
- Department of Chemistry, West Lafayette, IN, United States
- Purdue Center for Cancer Research, West Lafayette, IN, United States
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, United States
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8
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Chettri A, Yang T, Cole HD, Shi G, Cameron CG, McFarland SA, Dietzek-Ivanšić B. Using Biological Photophysics to Map the Excited-State Topology of Molecular Photosensitizers for Photodynamic Therapy. Angew Chem Int Ed Engl 2023; 62:e202301452. [PMID: 36827484 PMCID: PMC10079593 DOI: 10.1002/anie.202301452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 02/26/2023]
Abstract
This study employs TLD1433, a RuII -based photodynamic therapy (PDT) agent in human clinical trials, as a benchmark to establish protocols for studying the excited-state dynamics of photosensitizers (PSs) in cellulo, in the local environment provided by human cancer cells. Very little is known about the excited-state properties of any PS in live cells, and for TLD1433, it is terra incognita. This contribution targets a general problem in phototherapy, which is how to interrogate the light-triggered, function-determining processes of the PSs in the relevant biological environment, and establishes methodological advances to study the ultrafast photoinduced processes for TLD1433 when taken up by MCF7 cells. We generalize the methodological developments and results in terms of molecular physics by applying them to TLD1433's analogue TLD1633, making this study a benchmark to investigate the excited-state dynamics of phototoxic compounds in the complex biological environment.
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Affiliation(s)
- Avinash Chettri
- Department Functional Interfaces, Leibniz-Institute of Photonic Technology Jena, Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute of Physical Chemistry, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
| | - Tingxiang Yang
- Department Functional Interfaces, Leibniz-Institute of Photonic Technology Jena, Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute of Physical Chemistry, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
| | - Houston D Cole
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX-76019, USA
| | - Ge Shi
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX-76019, USA
| | - Colin G Cameron
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX-76019, USA
| | - Sherri A McFarland
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX-76019, USA
| | - Benjamin Dietzek-Ivanšić
- Department Functional Interfaces, Leibniz-Institute of Photonic Technology Jena, Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute of Physical Chemistry, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
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9
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Leighton RE, Alperstein AM, Punihaole D, Silva WR, Frontiera RR. Stimulated Raman versus Inverse Raman: Investigating Depletion Mechanisms for Super-Resolution Raman Microscopy. J Phys Chem B 2023; 127:26-36. [PMID: 36576851 DOI: 10.1021/acs.jpcb.2c04415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Super-resolution fluorescence microscopy has been critical in elucidating the nanoscale structure of biological systems. However, fluorescent labels bring difficulties such as perturbative labeling steps and photobleaching. Thus, label-free super-resolution techniques are of great interest, like our group's 2016 stimulated Raman scattering (SRS) technique, stimulated Raman depletion microscopy (SRDM). Inspired by stimulated emission depletion microscopy, SRDM uses a toroidally shaped beam to deplete the signal formed on the edges of the focal spot, resulting in SRS signal being detected from only a subdiffraction limited region. In initial works, the cause of the depletion was not thoroughly characterized. Here, we conclusively demonstrate suppression mechanisms in SRDM, while also contrasting approaches to super-resolution Raman microscopy on the Stokes and anti-Stokes sides of the spectrum. By monitoring the depletion of both the SRS and inverse Raman scattering (IRS) signal at a range of depletion powers, we observed other four-wave coherent Raman pathways that correspond to the introduction of the femtosecond depletion beam. In addition, we showed the depletion of the IRS signal, paving the way for a super-resolution imaging technique based on IRS, inverse raman depletion microscopy (IRDM). Combined, SRDM and IRDM offer label-free super-resolution imaging over a large spectral range to accommodate a variety of different sample constraints.
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Affiliation(s)
- Ryan E Leighton
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Ariel M Alperstein
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - David Punihaole
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - W Ruchira Silva
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota55455, United States
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota55455, United States
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10
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Schwarzl R, Heim P, Schiek M, Grimaldi D, Hohenau A, Krenn JR, Koch M. Transient absorption microscopy setup with multi-ten-kilohertz shot-to-shot subtraction and discrete Fourier analysis. OPTICS EXPRESS 2022; 30:34385-34395. [PMID: 36242451 DOI: 10.1364/oe.466272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/18/2022] [Indexed: 06/16/2023]
Abstract
Recording of transient absorption microscopy images requires fast detection of minute optical density changes, which is typically achieved with high-repetition-rate laser sources and lock-in detection. Here, we present a highly flexible and cost-efficient detection scheme based on a conventional photodiode and an USB oscilloscope with MHz bandwidth, that deviates from the commonly used lock-in setup and achieves benchmark sensitivity. Our scheme combines shot-to-shot evaluation of pump-probe and probe-only measurements, a home-built photodetector circuit optimized for low pulse energies applying low-pass amplification, and a custom evaluation algorithm based on Fourier transformation. Advantages of this approach include abilities to simultaneously monitor multiple pulse modulation frequencies, implement the detection of additional pulse sequences (e.g., pump-only), and expand to multiple parallel detection channels for wavelength-dispersive probing. With a 40 kHz repetition-rate laser system powering two non-collinear optical parametric amplifiers for wide tuneability, we find that laser pulse fluctuations limit the sensitivity of the setup, while the detection scheme has negligible contribution. We demonstrate the 2-D imaging performance of our transient absorption microscope with studies on micro-crystalline molecular thin films.
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11
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Lyu PT, Li QY, Wu P, Sun C, Kang B, Chen HY, Xu JJ. Decrypting Material Performance by Wide-field Femtosecond Interferometric Imaging of Energy Carrier Evolution. J Am Chem Soc 2022; 144:13928-13937. [PMID: 35866699 DOI: 10.1021/jacs.2c05735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Energy carrier evolution is crucial for material performance. Ultrafast microscopy has been widely applied to visualize the spatiotemporal evolution of energy carriers. However, direct imaging of a small amount of energy carriers on the nanoscale remains difficult due to extremely weak transient signals. Here, we present a method for ultrasensitive and high-throughput imaging of energy carrier evolution in space and time. This method combines femtosecond pump-probe techniques with interferometric scattering microscopy (iSCAT), named Femto-iSCAT. The interferometric principle and unique spatially modulated contrast enhancement enable the exploration of new science. We address three important and challenging problems: transport of different energy carriers at various interfaces, heterogeneous hot-electron distribution and relaxation in single plasmonic resonators, and distinct structure-dependent edge-state dynamics of carriers and excitons in optoelectronic semiconductors. Femto-iSCAT holds great potential as a universal tool for ultrasensitive imaging of energy carrier evolution in space and time.
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Affiliation(s)
- Pin-Tian Lyu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Qing-Yue Li
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Pei Wu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Chao Sun
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Bin Kang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
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12
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Zhang B, Yao T, Chen Y, Wang C, Bao Y, Wang Z, Zhao K, Ji M. Label-Free Delineation of Human Uveal Melanoma Infiltration With Pump–Probe Microscopy. Front Oncol 2022; 12:891282. [PMID: 35936703 PMCID: PMC9354715 DOI: 10.3389/fonc.2022.891282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Uveal melanoma (UM) is the most frequent primary intraocular malignancy in adults, characterized by melanin depositions in melanocytes located in the uveal tract in the eyes. Differentiation of melanin species (eumelanin and pheomelanin) is crucial in the diagnosis and management of UM, yet it remains inaccessible for conventional histology. Here, we report that femtosecond time-resolved pump-probe microscopy could provide label-free and chemical-specific detection of melanin species in human UM based on their distinct transient relaxation dynamics at the subpicosecond timescale. The method is capable of delineating the interface between melanoma and paracancerous regions on various tissue conditions, including frozen sections, paraffin sections, and fresh tissues. Moreover, transcriptome sequencing was conducted to confirm the active eumelanin synthesis in UM. Our results may hold potential for sensitive detection of tumor boundaries and biomedical research on melanin metabolism in UM.
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Affiliation(s)
- Bohan Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Multiscale Research Institute of Complex Systems, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Academy for Engineering and Technology, Human Phenome Institute, Fudan University, Shanghai, China
| | - Tengteng Yao
- Department of Ophthalmology, The Shanghai Tenth People’s Hospital of Tongji University, Shanghai, China
- Department of Ophthalmology, Shanghai Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Yaxin Chen
- State Key Laboratory of Surface Physics and Department of Physics, Multiscale Research Institute of Complex Systems, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Academy for Engineering and Technology, Human Phenome Institute, Fudan University, Shanghai, China
| | - Chuqiao Wang
- Department of Ophthalmology, The Shanghai Tenth People’s Hospital of Tongji University, Shanghai, China
- Department of Ophthalmology, Shanghai Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Yongyang Bao
- Department of Ophthalmology, Shanghai Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhaoyang Wang
- Department of Ophthalmology, The Shanghai Tenth People’s Hospital of Tongji University, Shanghai, China
- *Correspondence: Minbiao Ji, ; Keke Zhao, ; Zhaoyang Wang,
| | - Keke Zhao
- Department of Ophthalmology, Shanghai Children's Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, China
- *Correspondence: Minbiao Ji, ; Keke Zhao, ; Zhaoyang Wang,
| | - Minbiao Ji
- State Key Laboratory of Surface Physics and Department of Physics, Multiscale Research Institute of Complex Systems, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Academy for Engineering and Technology, Human Phenome Institute, Fudan University, Shanghai, China
- *Correspondence: Minbiao Ji, ; Keke Zhao, ; Zhaoyang Wang,
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13
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Leighton RE, Alperstein AM, Frontiera RR. Label-Free Super-Resolution Imaging Techniques. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2022; 15:37-55. [PMID: 35316608 PMCID: PMC9454238 DOI: 10.1146/annurev-anchem-061020-014723] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Biological and material samples contain nanoscale heterogeneities that are unresolvable with conventional microscopy techniques. Super-resolution fluorescence methods can break the optical diffraction limit to observe these features, but they require samples to be fluorescently labeled. Over the past decade, progress has been made toward developing super-resolution techniques that do not require the use of labels. These label-free techniques span a variety of different approaches, including structured illumination, transient absorption, infrared absorption, and coherent Raman spectroscopies. Many draw inspiration from widely successful fluorescence-based techniques such as stimulated emission depletion (STED) microscopy, photoactivated localization microscopy (PALM), and stochastic optical reconstruction microscopy (STORM). In this review, we discuss the progress made in these fields along with the current challenges and prospects in reaching resolutions comparable to those achieved with fluorescence-based methods.
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Affiliation(s)
- Ryan E Leighton
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA;
| | - Ariel M Alperstein
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA;
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA;
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14
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Wang E, Whitcomb LA, Chicco AJ, Wilson JW. Transient absorption spectroscopy and imaging of redox in muscle mitochondria. BIOMEDICAL OPTICS EXPRESS 2022; 13:2103-2116. [PMID: 35519286 PMCID: PMC9045930 DOI: 10.1364/boe.452559] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/03/2022] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
Mitochondrial redox is an important indicator of cell metabolism and health, with implications in cancer, diabetes, aging, neurodegenerative diseases, and mitochondrial disease. The most common method to observe redox of individual cells and mitochondria is through fluorescence of NADH and FAD+, endogenous cofactors serve as electron transport inputs to the mitochondrial respiratory chain. Yet this leaves out redox within the respiratory chain itself. To a degree, the missing information can be filled in by exogenous fluorophores, but at the risk of disturbed mitochondrial permeability and respiration. Here we show that variations in respiratory chain redox can be detected up by visible-wavelength transient absorption microscopy (TAM). In TAM, the selection of pump and probe wavelengths can provide multiphoton imaging contrast between non-fluorescent molecules. Here, we applied TAM with a pump at 520nm and probe at 450nm, 490nm, and 620nm to elicit redox contrast from mitochondrial respiratory chain hemeproteins. Experiments were performed with reduced and oxidized preparations of isolated mitochondria and whole muscle fibers, using mitochondrial fuels (malate, pyruvate, and succinate) to set up physiologically relevant oxidation levels. TAM images of muscle fibers were analyzed with multivariate curve resolution (MCR), revealing that the response at 620nm probe provides the best redox contrast and the most consistent response between whole cells and isolated mitochondria.
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Affiliation(s)
- Erkang Wang
- Department of Electrical & Computer
Engineering, Colorado State University,
1373 Campus Delivery, Fort Collins, CO 80523, USA
| | - Luke A. Whitcomb
- Department of Biomedical Sciences,
Colorado State University, 1601 Campus
Delivery, Fort Collins, CO 80523, USA
| | - Adam J. Chicco
- Department of Biomedical Sciences,
Colorado State University, 1601 Campus
Delivery, Fort Collins, CO 80523, USA
| | - Jesse W. Wilson
- Department of Electrical & Computer
Engineering, Colorado State University,
1373 Campus Delivery, Fort Collins, CO 80523, USA
- School of Biomedical Engineering,
Colorado State University, 1301 Campus
Delivery, Fort Collins, CO 80523, USA
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15
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Purz TL, Cundiff ST, Martin EW. Lock-in detector for accelerated nonlinear imaging. OPTICS LETTERS 2021; 46:4813-4816. [PMID: 34598206 DOI: 10.1364/ol.432353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/01/2021] [Indexed: 06/13/2023]
Abstract
We show that accelerated nonlinear imaging, such as stimulated Raman scattering and pump-probe imaging, is enabled by an order of magnitude reduction of data acquisition time when replacing the exponentially-weighted-moving-average low-pass filter in a lock-in amplifier with a simple-moving-average filter. We show that this simple-moving-average (box) lock-in yields a superior signal-to-noise ratio and suppression of extraneous modulations with short pixel dwell times, if one condition for the relation between the lock-in time constant and modulation frequencies is met. Our results, both theoretical and experimental, indicate that for nonlinear imaging applications, the box lock-in significantly outperforms conventional lock-in detection. These results facilitate the application of ultrafast and nonlinear imaging as a new standard for material characterization.
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16
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Malý P, Brixner T. Fluoreszenz‐detektierte Pump‐Probe‐Spektroskopie. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Pavel Malý
- Institut für Physikalische und Theoretische Chemie Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie Universität Würzburg Am Hubland 97074 Würzburg Deutschland
- Center for Nanosystems Chemistry (CNC) Universität Würzburg Theodor-Boveri-Weg 97074 Würzburg Deutschland
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17
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Malý P, Brixner T. Fluorescence-Detected Pump-Probe Spectroscopy. Angew Chem Int Ed Engl 2021; 60:18867-18875. [PMID: 34152074 PMCID: PMC8457154 DOI: 10.1002/anie.202102901] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/17/2021] [Indexed: 12/11/2022]
Abstract
We introduce a new approach to transient spectroscopy, fluorescence-detected pump-probe (F-PP) spectroscopy, that overcomes several limitations of traditional PP. F-PP suppresses excited-state absorption, provides background-free detection, removes artifacts resulting from pump-pulse scattering, from non-resonant solvent response, or from coherent pulse overlap, and allows unique extraction of excited-state dynamics under certain conditions. Despite incoherent detection, time resolution of F-PP is given by the duration of the laser pulses, independent of the fluorescence lifetime. We describe the working principle of F-PP and provide its theoretical description. Then we illustrate specific features of F-PP by direct comparison with PP, theoretically and experimentally. For this purpose, we investigate, with both techniques, a molecular squaraine heterodimer, core-shell CdSe/ZnS quantum dots, and fluorescent protein mCherry. F-PP is broadly applicable to chemical systems in various environments and in different spectral regimes.
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Affiliation(s)
- Pavel Malý
- Institut für Physikalische und Theoretische ChemieUniversität WürzburgAm Hubland97074WürzburgGermany
| | - Tobias Brixner
- Institut für Physikalische und Theoretische ChemieUniversität WürzburgAm Hubland97074WürzburgGermany
- Center for Nanosystems Chemistry (CNC)Universität WürzburgTheodor-Boveri-Weg97074WürzburgGermany
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18
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Duan S, Uragami C, Horiuchi K, Hino K, Wang XF, Sasaki SI, Tamiaki H, Hashimoto H. Hydroquinone redox mediator enhances the photovoltaic performances of chlorophyll-based bio-inspired solar cells. Commun Chem 2021; 4:118. [PMID: 36697644 PMCID: PMC9814249 DOI: 10.1038/s42004-021-00556-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 07/21/2021] [Indexed: 01/28/2023] Open
Abstract
Chlorophyll (Chl) derivatives have recently been proposed as photoactive materials in next-generation bio-inspired solar cells, because of their natural abundance, environmental friendliness, excellent photoelectric performance, and biodegradability. However, the intrinsic excitation dynamics of Chl derivatives remain unclear. Here, we show sub-nanosecond pump-probe time-resolved absorption spectroscopy of Chl derivatives both in solution and solid film states. We observe the formation of triplet-excited states of Chl derivatives both in deoxygenated solutions and in film samples by adding all-trans-β-carotene as a triplet scavenger. In addition, radical species of the Chl derivatives in solution were identified by adding hydroquinone as a cation radical scavenger and/or anion radical donor. These radical species (either cations or anions) can become carriers in Chl-derivative-based solar cells. Remarkably, the introduction of hydroquinone to the film samples enhanced the carrier lifetimes and the power conversion efficiency of Chl-based solar cells by 20% (from pristine 1.29% to 1.55%). This enhancement is due to a charge recombination process of Chl-A+/Chl-D-, which is based on the natural Z-scheme process of photosynthesis.
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Affiliation(s)
- Shengnan Duan
- grid.64924.3d0000 0004 1760 5735Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun, P. R. China ,Department of Applied Chemistry for Environment, Graduate School of Science and Technology, Kwansei Gakuen University, Sanda, Hyogo Japan ,grid.411587.e0000 0001 0381 4112School of Science, Chongqing University of Posts and Telecommunications, Chongqing, P. R. China
| | - Chiasa Uragami
- Department of Applied Chemistry for Environment, Graduate School of Science and Technology, Kwansei Gakuen University, Sanda, Hyogo Japan
| | - Kota Horiuchi
- Department of Applied Chemistry for Environment, Graduate School of Science and Technology, Kwansei Gakuen University, Sanda, Hyogo Japan
| | - Kazuki Hino
- Department of Applied Chemistry for Environment, Graduate School of Science and Technology, Kwansei Gakuen University, Sanda, Hyogo Japan
| | - Xiao-Feng Wang
- grid.64924.3d0000 0004 1760 5735Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun, P. R. China
| | - Shin-ichi Sasaki
- grid.419056.f0000 0004 1793 2541Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga Japan ,grid.262576.20000 0000 8863 9909Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga Japan
| | - Hitoshi Tamiaki
- grid.262576.20000 0000 8863 9909Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga Japan
| | - Hideki Hashimoto
- Department of Applied Chemistry for Environment, Graduate School of Science and Technology, Kwansei Gakuen University, Sanda, Hyogo Japan
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19
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Single 3.3 fs multiple plate compression light source in ultrafast transient absorption spectroscopy. Sci Rep 2021; 11:12847. [PMID: 34145343 PMCID: PMC8213815 DOI: 10.1038/s41598-021-92102-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/27/2021] [Indexed: 11/22/2022] Open
Abstract
Ultrafast transient absorption spectroscopy is a powerful tool to reveal excited state dynamics in various materials. Conventionally, probe pulses are generated via bulk supercontinuum generation or (noncollinear) optical parametric amplifiers whilst pump pulses are generated separately using (noncollinear) optical parametric amplifiers. These systems are limited by either their spectral density, stability, spectral range, and/or temporal compressibility. Recently, a new intense broadband light source is being developed, the multi-plate compression, which promises to overcome these limitations. In this paper, we analyze the supercontinuum generated by a single Multiple Plate Compression system to set a benchmark for its use in the field of ultrafast pump-probe spectroscopy. We have compressed the supercontinuum to 3.3 fs using chirp mirrors alone, making it an excellent candidate for pump-probe experiments requiring high temporal resolution. Furthermore, the single light source can be used to generate both probe and pump pulses due to its high spectral density (>14.5 nJ/nm) between 490 and 890 nm. The intensity has an average shot-to-shot relative standard deviation of 4.6 % over 490 to 890 nm, calculated over 2,000 sequential shots. By using only 1,000 shot pairs, a \documentclass[12pt]{minimal}
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\begin{document}$$2.6\times 10^{-4}$$\end{document}2.6×10-4 RMS is achieved. Finally, as a proof of concept, the transient absorption spectrum of a methylammonium lead iodide perovskite film is taken, showing great signal to noise with only 1,000 shot pairs. These results show great potential for the employment of this technique in other spectroscopic techniques such as coherent multidimensional spectroscopy.
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20
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Charge carrier mapping for Z-scheme photocatalytic water-splitting sheet via categorization of microscopic time-resolved image sequences. Nat Commun 2021; 12:3716. [PMID: 34140521 PMCID: PMC8211828 DOI: 10.1038/s41467-021-24061-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/27/2021] [Indexed: 11/08/2022] Open
Abstract
Photocatalytic water splitting system using particulate semiconductor materials is a promising strategy for converting solar energy into hydrogen and oxygen. In particular, visible-light-driven 'Z-scheme' printable photocatalyst sheets are cost-effective and scalable. However, little is known about the fundamental photophysical processes, which are key to explaining and promoting the photoactivity. Here, we applied the pattern-illumination time-resolved phase microscopy for a photocatalyst sheet composed of Mo-doped BiVO4 and Rh-doped SrTiO3 with indium tin oxide as the electron mediator to investigate photo-generated charge carrier dynamics. Using this method, we successfully observed the position- and structure-dependent charge carrier behavior and visualized the active/inactive sites in the sheets under the light irradiation via the time sequence images and the clustering analysis. This combination methodology could provide the material/synthesis optimization methods for the maximum performance of the photocatalyst sheets.
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21
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Gupta S, Wang E, Derrien S, Wilson JW. DR-RINS: Digital real-time relative intensity noise suppressor for pump-probe spectroscopy and microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:023704. [PMID: 33648049 DOI: 10.1063/5.0032376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 01/13/2021] [Indexed: 06/12/2023]
Abstract
Relative intensity noise (RIN) inherent in fiber lasers poses a serious obstacle to their use in pump-probe spectroscopy and imaging. RIN can be removed through an analog balanced detector, or, as we have previously shown, software adaptive noise cancellation (ANC) on digitized signals. One major drawback to software ANC is the added time required for digitizing and post-processing. In this article, we describe a design for ANC on a field-programmable gate array (FPGA), making use of high-level synthesis tools and fixed-point arithmetic to achieve real-time laser RIN suppression at 25 MHz sample rates. Unlike the software-ANC approach, the FPGA-ANC device can serve as a dedicated drop-in denoiser, placed between the detectors and a commercial lock-in amplifier. We demonstrate its application to transient absorption spectroscopy and microscopy, lowering the noise floor to ∼17 dB above the shot noise limit. Furthermore, we demonstrate a dramatic improvement in data acquisition time from ∼6 h to ∼5 min in a real-time imaging scenario.
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Affiliation(s)
- Saurabh Gupta
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Erkang Wang
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
| | | | - Jesse W Wilson
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523, USA
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22
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Blake MJ, Colon BA, Calhoun TR. Leaving the Limits of Linearity for Light Microscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2020; 124:24555-24565. [PMID: 34306294 PMCID: PMC8301257 DOI: 10.1021/acs.jpcc.0c07501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nonlinear microscopy has enabled additional modalities for chemical contrast, deep penetration into biological tissues, and the ability to collect dynamics on ultrafast timescales across heterogenous samples. The additional light fields introduced to a sample offer seemingly endless possibilities for variation to optimize and customize experimentation and the extraction of physical insight. This perspective highlights three areas of growth in this diverse field: the collection of information across multiple timescales, the selective imaging of interfacial chemistry, and the exploitation of quantum behavior for future imaging directions. Future innovations will leverage the work of the studies reviewed here as well as address the current challenges presented.
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Affiliation(s)
- Marea J Blake
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996
| | - Brandon A Colon
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996
| | - Tessa R Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996
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23
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Katayama K. Photo-excited charge carrier imaging by time-resolved pattern illumination phase microscopy. J Chem Phys 2020; 153:054201. [DOI: 10.1063/5.0009312] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kenji Katayama
- Department of Applied Chemistry, Chuo University, Tokyo 112-8551, Japan and PRESTO, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
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24
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Pegoraro AF, Moffatt DJ, Ridsdale A. Oblique angle transient-reflectivity laser-scanning microscopy for mineral imaging in natural ores. OPTICS EXPRESS 2020; 28:11946-11955. [PMID: 32403695 DOI: 10.1364/oe.388369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
The microscopic arrangement of different minerals in ores is of high interest for mine planning, mineral processing and extractive metallurgy. Many economically important, naturally occurring minerals are highly absorbing semiconductors. To characterize these materials, we have implemented pump-probe laser scanning microscopy (LSM) in a two-lens reflective configuration that offers efficient collection of signal light by using a combination of galvanometer and sample stage scanning. We show that the short-time (∼10 ps) pump-probe response of a material allows us to distinguish economically important sulfide minerals.
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