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Considerations in upconversion: A practical guide to sum-frequency generation spectrometer design and implementation. Biointerphases 2022; 17:021201. [PMID: 35473296 DOI: 10.1116/6.0001817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In this tutorial review, we discuss how the choice of upconversion pulse shape in broadband vibrational sum-frequency generation (SFG) spectrometer design impacts the chemical or physical insights one can obtain from a set of measurements. A time-domain picture of a vibrational coherence being mapped by a second optical field is described and the implications of how this mapping, or upconversion process, takes place are given in the context of several popular and emerging approaches found in the literature. Emphasis is placed on broadband frequency-domain measurements, where the choice of upconversion pulse enhances or limits the information contained in the SFG spectrum. We conclude with an outline for a flexible approach to SFG upconversion using pulse-shaping methods and a simple guide to design and optimize the associated instrumentation.
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Dramstad TA, Wu Z, Massari AM. Sum frequency generation as a proxy for ellipsometry: Not just a phase. J Chem Phys 2022; 156:110901. [DOI: 10.1063/5.0076252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Infrared refractive indices of organic materials are typically resolved through IR ellipsometry. This technique takes advantage of optical interference effects to solve the optical constants. These are the same effects that complicate the analysis of coherent spectroscopy experiments on thin films. Vibrational sum frequency generation is an interface-specific coherent spectroscopy that requires spectral modeling to account for optical interference effects to uncover interfacial molecular responses. Here, we explore the possibility of leveraging incident beam geometries and sample thicknesses to simultaneously obtain the molecular responses and refractive indices. Globally fitting a higher number of spectra with a single set of refractive indices increases the fidelity of the fitted parameters. Finally, we test our method on samples with a range of thicknesses and compare the results to those obtained by IR ellipsometry.
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Affiliation(s)
- Thorn A. Dramstad
- University of Minnesota–Twin Cities, 207 Pleasant St. SE, Minneapolis, Minnesota 55454, USA
| | - Zhihao Wu
- University of Minnesota–Twin Cities, 207 Pleasant St. SE, Minneapolis, Minnesota 55454, USA
| | - Aaron M. Massari
- University of Minnesota–Twin Cities, 207 Pleasant St. SE, Minneapolis, Minnesota 55454, USA
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Cotton DE, Roberts ST. Sensitivity of sum frequency generation experimental conditions to thin film interference effects. J Chem Phys 2021; 154:114704. [PMID: 33752341 DOI: 10.1063/5.0039897] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Sum-frequency generation (SFG) spectroscopy has furthered our understanding of the chemical interfaces that guide key processes in biology, catalysis, environmental science, and energy conversion. However, interpreting SFG spectra of systems containing several internal interfaces, such as thin film electronics, electrochemical cells, and biofilms, is challenging as different interfaces within these structures can produce interfering SFG signals. One potential way to address this issue is to carefully select experimental conditions that amplify the SFG signal of an interface of interest over all others. In this report, we investigate a model two-interface system to assess our ability to isolate the SFG signal from each interface. For SFG experiments performed in a reflective geometry, we find that there are few experimental conditions under which the SFG signal originating from either interface can be amplified and isolated from the other. However, by performing several measurements under conditions that alter their interference, we find that we can reconstruct each signal even in cases where the SFG signal from one interface is more than an order of magnitude smaller than its counterpart. The number of spectra needed for this reconstruction varies depending on the signal-to-noise level of the SFG dataset and the degree to which different experiments in a dataset vary in their sensitivity to each interface. Taken together, our work provides general guidelines for designing experimental protocols that can isolate SFG signals stemming from a particular region of interest within complex samples.
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Affiliation(s)
- Daniel E Cotton
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Sean T Roberts
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, USA
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Deng GH, Wei Q, Qian Y, Zhang T, Leng X, Rao Y. Development of interface-/surface-specific two-dimensional electronic spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:023104. [PMID: 33648131 DOI: 10.1063/5.0019564] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
Structures, kinetics, and chemical reactivities at interfaces and surfaces are key to understanding many of the fundamental scientific problems related to chemical, material, biological, and physical systems. These steady-state and dynamical properties at interfaces and surfaces require even-order techniques with time-resolution and spectral-resolution. Here, we develop fourth-order interface-/surface-specific two-dimensional electronic spectroscopy, including both two-dimensional electronic sum frequency generation (2D-ESFG) spectroscopy and two-dimensional electronic second harmonic generation (2D-ESHG) spectroscopy, for structural and dynamics studies of interfaces and surfaces. The 2D-ESFG and 2D-ESHG techniques were based on a unique laser source of broadband short-wave IR from 1200 nm to 2200 nm from a home-built optical parametric amplifier. With the broadband short-wave IR source, surface spectra cover most of the visible light region from 480 nm to 760 nm. A translating wedge-based identical pulses encoding system (TWINs) was introduced to generate a phase-locked pulse pair for coherent excitation in the 2D-ESFG and 2D-ESHG. As an example, we demonstrated surface dark states and their interactions of the surface states at p-type GaAs (001) surfaces with the 2D-ESFG and 2D-ESHG techniques. These newly developed time-resolved and interface-/surface-specific 2D spectroscopies would bring new information for structure and dynamics at interfaces and surfaces in the fields of the environment, materials, catalysis, and biology.
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Affiliation(s)
- Gang-Hua Deng
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Qianshun Wei
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Yuqin Qian
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Tong Zhang
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Xuan Leng
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
| | - Yi Rao
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
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Li H, Zhao Y, Li Y, Liu WT. Narrowband nonlinear optical spectroscopy with spatially chirped broadband pulses. OPTICS LETTERS 2021; 46:54-57. [PMID: 33362014 DOI: 10.1364/ol.410335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/22/2020] [Indexed: 06/12/2023]
Abstract
Nonlinear optical vibrational spectroscopies are powerful experimental tools for inspecting material properties that are difficult to acquire otherwise. As ultrafast lasers used in such experiments are typically of much broader bandwidth than vibrational modes, narrowband filtering is usually essential, and the utility of laser energy is often highly inefficient. Here we introduce an experimental scheme to break this trade-off. A broadband beam is spatially chirped as it reaches the sample, and generates sum-frequency signals upon overlapping with another broadband, unchirped beam. A narrowband spectrum can then be retrieved from the spatially dispersed image of signals, with both broadband pulses fully utilized. The scheme is also readily employed as a spatially resolved spectroscopy technique without scanning, and can be easily extended to other wave-mixing experiments.
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Cassabaum AA, Bera K, Rich CC, Nebgen BR, Kwang SY, Clapham ML, Frontiera RR. Femtosecond stimulated Raman spectro-microscopy for probing chemical reaction dynamics in solid-state materials. J Chem Phys 2020; 153:030901. [DOI: 10.1063/5.0009976] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Alyssa A. Cassabaum
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Kajari Bera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Christopher C. Rich
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Bailey R. Nebgen
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Siu Yi Kwang
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Margaret L. Clapham
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Renee R. Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Bera K, Kwang SY, Cassabaum AA, Rich CC, Frontiera RR. Facile Background Discrimination in Femtosecond Stimulated Raman Spectroscopy Using a Dual-Frequency Raman Pump Technique. J Phys Chem A 2019; 123:7932-7939. [DOI: 10.1021/acs.jpca.9b02473] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kajari Bera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Siu Yi Kwang
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Alyssa A. Cassabaum
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Christopher C. Rich
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Renee R. Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Prichett IG, Massari AM. Simplified sum frequency generation using a narrow free-spectral-range etalon. OPTICS LETTERS 2018; 43:4747-4750. [PMID: 30272730 DOI: 10.1364/ol.43.004747] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 08/27/2018] [Indexed: 06/08/2023]
Abstract
We report the implementation of a narrow free-spectral-range Fabry-Perot etalon for multiplex vibrational sum frequency generation (VSFG) spectroscopy. Moreover, we demonstrate the use of the etalon reflection to simultaneously generate a broadband infrared pulse, which enables a multiplex VSFG spectrometer using a total of 0.58 W. VSFG spectra with and without a nonresonant-suppressed background were simultaneously collected utilizing time asymmetry in the upconverting pulse. Two examples are demonstrated in which spectral perturbations can be induced by the time-asymmetric pulse even without nonresonant suppression.
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