1
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Casas AM, Idris NS, Wen V, Patterson JP, Ge NH. Scattering Elimination in 2D IR Immune from Detector Artifacts. J Phys Chem B 2024; 128:8835-8845. [PMID: 39188212 PMCID: PMC11403676 DOI: 10.1021/acs.jpcb.4c04220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
Highly scattering samples, such as polymer droplets or solid-state powders, are difficult to study via coherent two-dimensional infrared (2D IR) spectroscopy. Previously, researchers have employed (quasi-) phase cycling, local-oscillator chopping, and polarization control to reduce scattering, but the latter method poses a limit on polarization-dependent measurements. Here, we present a method for Scattering Elimination Immune from Detector Artifacts (SEIFDA) in pump-probe 2D IR experiments. Our method extends the negative probe delay method of removing scattering from pump-probe spectroscopy to 2D experiments. SEIFDA works well for all polarizations when combined with the optimized noise reduction scheme to remove additive and multiplicative noise. We demonstrate that our method can be employed with any polarization scheme and reliably lowers the scattering at parallel polarization to comparable levels to the conventional 8-frame phase cycling with probe chopping (8FPCPC) at perpendicular polarization. Our system can acquire artifact free spectra in parallel polarization when the signal intensity is as little as 5% of the intensity of the interference between the pump pulses scattered into the detector. It reduces the time required to characterize the scattering term by at least 50% over 8FPCPC. Through detailed analysis of detector nonlinearity, we show that the performance of 8FPCPC can be improved by incorporating nonlinear correction factors, but it is still worse than that of SEIFDA. Application of SEIFDA to study the encapsulation of Nile red in polymer droplets demonstrates that this method will be very useful for probing highly scattering systems.
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Affiliation(s)
- Anneka Miller Casas
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Nehal S Idris
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Victor Wen
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Joseph P Patterson
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Nien-Hui Ge
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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2
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Hunt NT. Biomolecular infrared spectroscopy: making time for dynamics. Chem Sci 2024; 15:414-430. [PMID: 38179520 PMCID: PMC10763549 DOI: 10.1039/d3sc05223k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 11/24/2023] [Indexed: 01/06/2024] Open
Abstract
Time resolved infrared spectroscopy of biological molecules has provided a wealth of information relating to structural dynamics, conformational changes, solvation and intermolecular interactions. Challenges still exist however arising from the wide range of timescales over which biological processes occur, stretching from picoseconds to minutes or hours. Experimental methods are often limited by vibrational lifetimes of probe groups, which are typically on the order of picoseconds, while measuring an evolving system continuously over some 18 orders of magnitude in time presents a raft of technological hurdles. In this Perspective, a series of recent advances which allow biological molecules and processes to be studied over an increasing range of timescales, while maintaining ultrafast time resolution, will be reviewed, showing that the potential for real-time observation of biomolecular function draws ever closer, while offering a new set of challenges to be overcome.
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Affiliation(s)
- Neil T Hunt
- Department of Chemistry and York Biomedical Research Institute, University of York Heslington York YO10 5DD UK
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3
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Appleby MV, Cowin RA, Ivalo II, Peralta-Arriaga SL, Robertson CC, Bartlett S, Fitzpatrick A, Dent A, Karras G, Diaz-Moreno S, Chekulaev D, Weinstein JA. Ultrafast electronic, infrared, and X-ray absorption spectroscopy study of Cu(I) phosphine diimine complexes. Faraday Discuss 2023; 244:391-410. [PMID: 37415486 DOI: 10.1039/d3fd00027c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
The study aims to understand the role of the transient bonding in the interplay between the structural and electronic changes in heteroleptic Cu(I) diimine diphosphine complexes. This is an emerging class of photosensitisers which absorb in the red region of the spectrum, whilst retaining a sufficiently long excited state lifetime. Here, the dynamics of these complexes are explored by transient absorption (TA) and time-resolved infrared (TRIR) spectroscopy, which reveal ultrafast intersystem crossing and structural distortion occurring. Two potential mechanisms affecting excited state decay in these complexes involve a transient formation of a solvent adduct, made possible by the opening up of the Cu coordination centre in the excited state due to structural distortion, and by a transient coordination of the O-atom of the phosphine ligand to the copper center. X-ray absorption studies of the ground electronic state have been conducted as a prerequisite for the upcoming X-ray spectroscopy studies which will directly determine structural dynamics. The potential for these complexes to be used in bimolecular applications is confirmed by a significant yield of singlet oxygen production.
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Affiliation(s)
- Martin V Appleby
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK.
| | - Rory A Cowin
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK.
| | - Iona I Ivalo
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK.
| | | | - Craig C Robertson
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK.
| | - Stuart Bartlett
- Diamond Light Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Ann Fitzpatrick
- Diamond Light Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Andrew Dent
- Diamond Light Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Gabriel Karras
- Diamond Light Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Sofia Diaz-Moreno
- Diamond Light Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Dimitri Chekulaev
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK.
| | - Julia A Weinstein
- Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK.
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4
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Abstract
Optimization of pump-probe signal requires a complete understanding of how signal scales with experimental factors. In simple systems, signal scales quadratically with molar absorptivity, and linearly with fluence, concentration, and path length. In practice, scaling factors weaken beyond certain thresholds (e.g., OD > 0.1) due to asymptotic limits related to optical density, fluence and path length. While computational models can accurately account for subdued scaling, quantitative explanations often appear quite technical in the literature. This Perspective aims to present a simpler understanding of the subject with concise formulas for estimating absolute magnitudes of signal under both ordinary and asymptotic scaling conditions. This formulation may be more appealing for spectroscopists seeking rough estimates of signal or relative comparisons. We identify scaling dependencies of signal with respect to experimental parameters and discuss applications for improving signal under broad conditions. We also review other signal enhancement methods, such as local-oscillator attenuation and plasmonic enhancement, and discuss respective benefits and challenges regarding asymptotic limits that signal cannot exceed.
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Affiliation(s)
- Kevin C Robben
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA
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5
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Al-Mualem ZA, Baiz CR. Generative Adversarial Neural Networks for Denoising Coherent Multidimensional Spectra. J Phys Chem A 2022; 126:3816-3825. [PMID: 35668543 DOI: 10.1021/acs.jpca.2c02605] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ultrafast spectroscopy often involves measuring weak signals and long data acquisition times. Spectra are typically collected as a "pump-probe" spectrum by measuring differences in intensity across laser shots. Shot-to-shot intensity fluctuations are most often the primary source of noise in ultrafast spectroscopy. Here, we present a novel approach for denoising ultrafast two-dimensional infrared (2D IR) spectra using conditional generative adversarial neural networks (cGANNs). The cGANN approach is able to eliminate shot-to-shot noise and reconstruct the line shapes present in the noisy input spectrum. We present a general approach for training the cGANN using matched pairs of noisy and clean synthetic 2D IR spectra based on the Kubo-line shape model for a three-level system. Experimental shot-to-shot laser noise is added to synthetic spectra to recreate the noise profile present in measured experimental spectra. The cGANNs can recover line shapes from synthetic 2D IR spectra with signal-to-noise ratios as low as 2:1, while largely preserving the key features such as center frequencies, line widths, and diagonal elongation. In addition, we benchmark the performance of the cGANN using experimental 2D IR spectra of an ester carbonyl vibrational probe and demonstrate that, by applying the cGANN denoising approach, we can extract the frequency-frequency time correlation function (FFCF) from reconstructed spectra using a nodal-line slope analysis. Finally, we provide a set of practical guidelines for extending the denoising method to other coherent multidimensional spectroscopies.
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Affiliation(s)
- Ziareena A Al-Mualem
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Carlos R Baiz
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
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6
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Chiral control of spin-crossover dynamics in Fe(II) complexes. Nat Chem 2022; 14:739-745. [PMID: 35618767 DOI: 10.1038/s41557-022-00933-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 03/14/2022] [Indexed: 11/08/2022]
Abstract
Iron-based spin-crossover complexes hold tremendous promise as multifunctional switches in molecular devices. However, real-world technological applications require the excited high-spin state to be kinetically stable-a feature that has been achieved only at cryogenic temperatures. Here we demonstrate high-spin-state trapping by controlling the chiral configuration of the prototypical iron(II)tris(4,4'-dimethyl-2,2'-bipyridine) in solution, associated for stereocontrol with the enantiopure Δ- or Λ-enantiomer of tris(3,4,5,6-tetrachlorobenzene-1,2-diolato-κ2O1,O2)phosphorus(V) (P(O2C6Cl4)3- or TRISPHAT) anions. We characterize the high-spin-state relaxation using broadband ultrafast circular dichroism spectroscopy in the deep ultraviolet in combination with transient absorption and anisotropy measurements. We find that the high-spin-state decay is accompanied by ultrafast changes of its optical activity, reflecting the coupling to a symmetry-breaking torsional twisting mode, contrary to the commonly assumed picture. The diastereoselective ion pairing suppresses the vibrational population of the identified reaction coordinate, thereby achieving a fourfold increase of the high-spin-state lifetime. More generally, our results motivate the synthetic control of the torsional modes of iron(II) complexes as a complementary route to manipulate their spin-crossover dynamics.
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7
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Uriarte LM, Vitale R, Niziński S, Hadjidemetriou K, Zala N, Lukacs A, Greetham GM, Sazanovich IV, Weik M, Ruckebusch C, Meech SR, Sliwa M. Structural Information about the trans-to- cis Isomerization Mechanism of the Photoswitchable Fluorescent Protein rsEGFP2 Revealed by Multiscale Infrared Transient Absorption. J Phys Chem Lett 2022; 13:1194-1202. [PMID: 35085441 DOI: 10.1021/acs.jpclett.1c02920] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
RsEGFP2 is a reversibly photoswitchable fluorescent protein used in super-resolved optical microscopies, which can be toggled between a fluorescent On state and a nonfluorescent Off state. Previous time-resolved ultraviolet-visible spectroscopic studies have shown that the Off-to-On photoactivation extends over the femto- to millisecond time scale and involves two picosecond lifetime excited states and four ground state intermediates, reflecting a trans-to-cis excited state isomerization, a millisecond deprotonation, and protein structural reorganizations. Femto- to millisecond time-resolved multiple-probe infrared spectroscopy (TRMPS-IR) can reveal structural aspects of intermediate species. Here we apply TRMPS-IR to rsEGFP2 and implement a Savitzky-Golay derivative analysis to correct for baseline drift. The results reveal that a subpicosecond twisted excited state precursor controls the trans-to-cis isomerization and the chromophore reaches its final position in the protein pocket within 100 ps. A new step with a time constant of 42 ns is reported and assigned to structural relaxation of the protein that occurs prior to the deprotonation of the chromophore on the millisecond time scale.
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Affiliation(s)
- Lucas M Uriarte
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
| | - Raffaele Vitale
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
| | - Stanisław Niziński
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
- Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, Poznan 61-614, Poland
| | | | - Ninon Zala
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Gregory M Greetham
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, U.K
| | - Igor V Sazanovich
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, U.K
| | - Martin Weik
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Cyril Ruckebusch
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Michel Sliwa
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
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8
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Vinogradov I, Singh S, Lyle H, Paolino M, Mandal A, Rossmeisl J, Cuk T. Free energy difference to create the M-OH * intermediate of the oxygen evolution reaction by time-resolved optical spectroscopy. NATURE MATERIALS 2022; 21:88-94. [PMID: 34725518 DOI: 10.1038/s41563-021-01118-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
Theoretical descriptors differentiate the catalytic activity of materials for the oxygen evolution reaction by the strength of oxygen binding in the reactive intermediate created upon electron transfer. Recently, time-resolved spectroscopy of a photo-electrochemically driven oxygen evolution reaction followed the vibrational and optical spectra of this intermediate, denoted M-OH*. However, these inherently kinetic experiments have not been connected to the relevant thermodynamic quantities. Here we discover that picosecond optical spectra of the Ti-OH* population on lightly doped SrTiO3 are ordered by the surface hydroxylation. A Langmuir isotherm as a function of pH extracts an effective equilibrium constant relatable to the free energy difference of the first oxygen evolution reaction step. Thus, time-resolved spectroscopy of the catalytic surface reveals both kinetic and energetic information of elementary reaction steps, which provides a critical new connection between theory and experiment by which to tailor the pathway of water oxidation and other surface reactions.
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Affiliation(s)
- Ilya Vinogradov
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, CO, USA
| | - Suryansh Singh
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, CO, USA
- Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, CO, USA
| | - Hanna Lyle
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, CO, USA
- Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, CO, USA
| | - Michael Paolino
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, CO, USA
- Department of Physics, University of Colorado, Boulder, Boulder, CO, USA
| | - Aritra Mandal
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, CO, USA.
| | - Jan Rossmeisl
- Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Tanja Cuk
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, CO, USA.
- Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, CO, USA.
- Department of Chemistry, University of Colorado, Boulder, Boulder, CO, USA.
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9
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Robben KC, Cheatum CM. Least-Squares Fitting of Multidimensional Spectra to Kubo Line-Shape Models. J Phys Chem B 2021; 125:12876-12891. [PMID: 34783568 PMCID: PMC8630800 DOI: 10.1021/acs.jpcb.1c08764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
We report a comprehensive
study of the efficacy of least-squares
fitting of multidimensional spectra to generalized Kubo line-shape
models and introduce a novel least-squares fitting metric, termed
the scale invariant gradient norm (SIGN), that enables a highly reliable
and versatile algorithm. The precision of dephasing parameters is
between 8× and 50× better for nonlinear model fitting compared
to that for the centerline-slope (CLS) method, which effectively increases
data acquisition efficiency by 1–2 orders of magnitude. Whereas
the CLS method requires sequential fitting of both the nonlinear and
linear spectra, our model fitting algorithm only requires nonlinear
spectra but accurately predicts the linear spectrum. We show an experimental
example in which the CLS time constants differ by 60% for independent
measurements of the same system, while the Kubo time constants differ
by only 10% for model fitting. This suggests that model fitting is
a far more robust method of measuring spectral diffusion than the
CLS method, which is more susceptible to structured residual signals
that are not removable by pure solvent subtraction. Statistical analysis
of the CLS method reveals a fundamental oversight in accounting for
the propagation of uncertainty by Kubo time constants in the process
of fitting to the linear absorption spectrum. A standalone desktop
app and source code for the least-squares fitting algorithm are freely
available, with example line-shape models and data. We have written
the MATLAB source code in a generic framework where users may supply
custom line-shape models. Using this application, a standard desktop
fits a 12-parameter generalized Kubo model to a 106 data-point
spectrum in a few minutes.
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Affiliation(s)
- Kevin C Robben
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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10
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Kübel J, Westenhoff S, Maj M. Giving voice to the weak: Application of active noise reduction in transient infrared spectroscopy. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.139059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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11
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Singh S, Lyle H, D'Amario L, Magnano E, Vinogradov I, Cuk T. Coherent Acoustic Interferometry during the Photodriven Oxygen Evolution Reaction Associates Strain Fields with the Reactive Oxygen Intermediate (Ti-OH*). J Am Chem Soc 2021; 143:15984-15997. [PMID: 34554748 DOI: 10.1021/jacs.1c04976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The oxygen evolution reaction (OER) from water requires the formation of metastable, reactive oxygen intermediates to enable oxygen-oxygen bond formation. Conversely, such reactive intermediates could also structurally modify the catalyst. A descriptor for the overall catalytic activity, the first electron and proton transfer OER intermediate from water, (M-OH*), has been associated with significant distortions of the metal-oxygen bonds upon charge-trapping. Time-resolved spectroscopy of in situ, photodriven OER on transition metal oxide surfaces has characterized M-OH* for the charge trapping and the symmetry of the lattice distortions by optical and vibrational transitions, respectively, but had yet to detect an interfacial strain field arising from a surface coverage M-OH*. Here, we utilize picosecond, coherent acoustic interferometry to detect the uniaxial strain normal to the SrTiO3/aqueous interface directly caused by Ti-OH*. The spectral analysis applies a fairly general methodology for detecting a combination of the spatial extent, magnitude, and generation time of the interfacial strain through the coherent oscillations' phase. For lightly n-doped SrTiO3, we identify the strain generation time (1.31 ps), which occurs simultaneously with Ti-OH* formation, and a tensile strain of 0.06% (upper limit 0.6%). In addition to fully characterizing this intermediate across visible, mid-infrared, and now GHz-THz probes on SrTiO3, we show that strain fields occur with the creation of some M-OH*, which modifies design strategies for tuning catalytic activity and provides insight into photo-induced degradation so prevalent for OER. To that end, the work put forth here provides a unique methodology to characterize intermediate-induced interfacial strain across OER catalysts.
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Affiliation(s)
- Suryansh Singh
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, Colorado 80303, United States.,Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, Colorado 80303, United States
| | - Hanna Lyle
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, Colorado 80303, United States.,Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, Colorado 80303, United States
| | - Luca D'Amario
- Department of Chemistry-Ångström Laboratories, Uppsala University, Box 523, SE75120 Uppsala, Sweden.,Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Elena Magnano
- IOM CNR Laboratorio TASC, 34149 Basovizza (TS), Italy.,Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa
| | - Ilya Vinogradov
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, Colorado 80303, United States
| | - Tanja Cuk
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado, Boulder, Boulder, Colorado 80303, United States.,Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, Colorado 80303, United States.,Department of Chemistry, University of Colorado, Boulder, Boulder, Colorado 80303, United States
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12
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Vinogradov I, Feng Y, Kumar SKK, Guo C, Udagawa NS, Ge NH. Ultrafast vibrational dynamics of the tyrosine ring mode and its application to enkephalin insertion into phospholipid membranes as probed by two-dimensional infrared spectroscopy. J Chem Phys 2021; 155:035102. [PMID: 34293882 DOI: 10.1063/5.0054428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Enkephalins are small opioid peptides whose binding conformations are catalyzed by phospholipid membranes. Binding to opioid receptors is determined by the orientation of tyrosine and phenylalanine side chains. In this work, we investigate the effects of different charged phospholipid headgroups on the insertion of the tyrosine side chain into a lipid bilayer using a combination of 2D IR spectroscopy, anharmonic DFT calculations, and third order response function modeling. The insertion is probed by using the ∼1515 cm-1 tyrosine ring breathing mode, which we found exhibits rich vibrational dynamics on the picosecond timescale. These dynamics include rapid intramolecular vibrational energy redistribution (IVR), where some of the energy ends up in a dark state that shows up as an anharmonically shifted combination band. The waiting-time dependent 2D IR spectra also show an unusual line shape distortion that affects the extraction of the frequency-frequency correlation function (FFCF), which is the dynamic observable of interest that reflects the tyrosine side chain's insertion into the lipid bilayer. We proposed three models to account for this distortion: a hot-state exchange model, a local environment dependent IVR model, and a coherence transfer model. A qualitative analysis of these models suggests that the local environment dependent IVR rate best explains the line shape distortion, while the coherence transfer model best reproduced the effects on the FFCF. Even with these complex dynamics, we found that the tyrosine ring mode's FFCF is qualitatively correlated with the degree of insertion expected from the different phospholipid headgroups.
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Affiliation(s)
- Ilya Vinogradov
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Yuan Feng
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - S K Karthick Kumar
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Chenxu Guo
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Nina Saki Udagawa
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Nien-Hui Ge
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
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13
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Ultrafast structural changes within a photosynthetic reaction centre. Nature 2021; 589:310-314. [PMID: 33268896 DOI: 10.1038/s41586-020-3000-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/28/2020] [Indexed: 01/29/2023]
Abstract
Photosynthetic reaction centres harvest the energy content of sunlight by transporting electrons across an energy-transducing biological membrane. Here we use time-resolved serial femtosecond crystallography1 using an X-ray free-electron laser2 to observe light-induced structural changes in the photosynthetic reaction centre of Blastochloris viridis on a timescale of picoseconds. Structural perturbations first occur at the special pair of chlorophyll molecules of the photosynthetic reaction centre that are photo-oxidized by light. Electron transfer to the menaquinone acceptor on the opposite side of the membrane induces a movement of this cofactor together with lower amplitude protein rearrangements. These observations reveal how proteins use conformational dynamics to stabilize the charge-separation steps of electron-transfer reactions.
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14
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Farrell KM, Ostrander JS, Jones AC, Yakami BR, Dicke SS, Middleton CT, Hamm P, Zanni MT. Shot-to-shot 2D IR spectroscopy at 100 kHz using a Yb laser and custom-designed electronics. OPTICS EXPRESS 2020; 28:33584-33602. [PMID: 33115018 PMCID: PMC7679191 DOI: 10.1364/oe.409360] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/08/2020] [Accepted: 10/08/2020] [Indexed: 05/29/2023]
Abstract
The majority of 2D IR spectrometers operate at 1-10 kHz using Ti:Sapphire laser technology. We report a 2D IR spectrometer designed around Yb:KGW laser technology that operates shot-to-shot at 100 kHz. It includes a home-built OPA, a mid-IR pulse shaper, and custom-designed electronics with optional on-chip processing. We report a direct comparison between Yb:KGW and Ti:Sapphire based 2D IR spectrometers. Even though the mid-IR pulse energy is much lower for the Yb:KGW driven system, there is an 8x improvement in signal-to-noise over the 1 kHz Ti:Sapphire driven spectrometer to which it is compared. Experimental data is shown for sub-millimolar concentrations of amides. Advantages and disadvantages of the design are discussed, including thermal background that arises at high repetition rates. This fundamental spectrometer design takes advantage of newly available Yb laser technology in a new way, providing a straightforward means of enhancing sensitivity.
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Affiliation(s)
- Kieran M. Farrell
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Josh S. Ostrander
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Currently with the Department of Chemistry, Indiana Wesleyan University, Marion, Indiana 46953, USA
| | - Andrew C. Jones
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Currently with the Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Albuquerque, New Mexico 87185, USA
| | - Baichhabi R. Yakami
- PhaseTech Spectroscopy, 2810 Crossroads Drive, Suite 4000 Madison, Wisconsin 53718, USA
| | - Sidney S. Dicke
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Chris T. Middleton
- PhaseTech Spectroscopy, 2810 Crossroads Drive, Suite 4000 Madison, Wisconsin 53718, USA
| | - Peter Hamm
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Martin T. Zanni
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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15
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Robben KC, Cheatum CM. Edge-pixel referencing suppresses correlated baseline noise in heterodyned spectroscopies. J Chem Phys 2020; 152:094201. [PMID: 33480715 DOI: 10.1063/1.5134987] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Referencing schemes are commonly used in heterodyned spectroscopies to mitigate correlated baseline noise arising from shot-to-shot fluctuations of the local oscillator. Although successful, these methods rely on careful pixel-to-pixel matching between the two spectrographs. A recent scheme introduced by Feng et al. [Opt. Express 27(15), 20323-20346 (2019)] employed a correlation matrix to allow free mapping between dissimilar spectrographs, leading to the first demonstration of floor noise limited detection on a multichannel array used in heterodyned spectroscopy. In addition to their primary results using a second reference spectrometer, Feng et al. briefly demonstrated the flexibility of their method by referencing to same-array pixels at the two spectral edges (i.e., edge-pixel referencing). We present a comprehensive study of this approach, which we term edge-pixel referencing, including optimization of the approach, assessment of the performance, and determination of the effects of background responses. We show that, within some limitations, the distortions due to background signals will not affect the 2D IR line shape or amplitude and can be mitigated by band narrowing of the pump beams. We also show that the performance of edge-pixel referencing is comparable to that of referencing to a second spectrometer in terms of noise suppression and that the line shapes and amplitudes of the spectral features are, within the measurement error, identical. Altogether, these results demonstrate that edge-pixel referencing is a powerful approach for noise suppression in heterodyned spectroscopies, which requires no new hardware and, so, can be implemented as a software solution for anyone performing heterodyned spectroscopy with multichannel array detectors already.
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Affiliation(s)
- Kevin C Robben
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA
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16
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Kübel J, Chenchiliyan M, Ooi SA, Gustavsson E, Isaksson L, Kuznetsova V, Ihalainen JA, Westenhoff S, Maj M. Transient IR spectroscopy identifies key interactions and unravels new intermediates in the photocycle of a bacterial phytochrome. Phys Chem Chem Phys 2020; 22:9195-9203. [DOI: 10.1039/c9cp06995j] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Infra-red spectroscopy advances our understanding of how photosensory proteins carry their function.
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Affiliation(s)
- Joachim Kübel
- Department of Chemistry and Molecular Biology
- University of Gothenburg
- Gothenburg 40530
- Sweden
| | - Manoop Chenchiliyan
- Department of Chemistry and Molecular Biology
- University of Gothenburg
- Gothenburg 40530
- Sweden
| | - Saik Ann Ooi
- Department of Chemistry and Molecular Biology
- University of Gothenburg
- Gothenburg 40530
- Sweden
| | - Emil Gustavsson
- Department of Chemistry and Molecular Biology
- University of Gothenburg
- Gothenburg 40530
- Sweden
| | - Linnéa Isaksson
- Department of Chemistry and Molecular Biology
- University of Gothenburg
- Gothenburg 40530
- Sweden
| | - Valentyna Kuznetsova
- Nanoscience Center
- Department of Biological and Environmental Science
- University of Jyväskylä
- Jyväskylä 40014
- Finland
| | - Janne A. Ihalainen
- Nanoscience Center
- Department of Biological and Environmental Science
- University of Jyväskylä
- Jyväskylä 40014
- Finland
| | - Sebastian Westenhoff
- Department of Chemistry and Molecular Biology
- University of Gothenburg
- Gothenburg 40530
- Sweden
| | - Michał Maj
- Department of Chemistry and Molecular Biology
- University of Gothenburg
- Gothenburg 40530
- Sweden
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