1
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Verduci R, Creazzo F, Tavella F, Abate S, Ampelli C, Luber S, Perathoner S, Cassone G, Centi G, D'Angelo G. Water Structure in the First Layers on TiO 2: A Key Factor for Boosting Solar-Driven Water-Splitting Performances. J Am Chem Soc 2024. [PMID: 38909313 DOI: 10.1021/jacs.4c05042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2024]
Abstract
The water hydrogen-bonded network is strongly perturbed in the first layers in contact with the semiconductor surface. Even though this aspect influences the outer-sphere electron transfer, it was not recognized that it is a crucial factor impacting the solar-driven water-splitting performances. To fill this gap, we have selected two TiO2 anatase samples (with and without B-doping), and by extensive experimental and computational investigations, we have demonstrated that the remarkable 5-fold increase in water-splitting photoactivity of the B-doped sample cannot be ascribed to effects typically associated to enhanced photocatalytic properties, such as band gap, heterojunctions, crystal facets, and other aspects. Studying these samples by combining FTIR measurements under controlled humidity with first-principles simulations sheds light on the role and nature of the first-layer water structure in contact with the photocatalyst surfaces. It turns out that the doping hampers the percolation of tetrahedrally coordinated water molecules while enhancing the population of topological H-bond defects forming approximately linear H-bonded chains. This work unveils how doping the semiconductor surface affects the local electric field, determining the water splitting rate by influencing the H-bond topologies in the first water layers. This evidence opens new prospects for designing efficient photocatalysts for water splitting.
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Affiliation(s)
- Rosaria Verduci
- Department of Mathematical and Computational Sciences, Physical Science and Earth Science (MIFT), University of Messina, V.le F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Fabrizio Creazzo
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Francesco Tavella
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (ChiBioFarAm), University of Messina, ERIC aisbl and CASPE/INSTM, 98166 Messina, Italy
| | - Salvatore Abate
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (ChiBioFarAm), University of Messina, ERIC aisbl and CASPE/INSTM, 98166 Messina, Italy
| | - Claudio Ampelli
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (ChiBioFarAm), University of Messina, ERIC aisbl and CASPE/INSTM, 98166 Messina, Italy
| | - Sandra Luber
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Siglinda Perathoner
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (ChiBioFarAm), University of Messina, ERIC aisbl and CASPE/INSTM, 98166 Messina, Italy
| | - Giuseppe Cassone
- Institute for Chemical-Physical Processes, National Research Council of Italy (IPCF-CNR), Viale F. Stagno d'Alcontres 37, 98158 Messina, Italy
| | - Gabriele Centi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (ChiBioFarAm), University of Messina, ERIC aisbl and CASPE/INSTM, 98166 Messina, Italy
| | - Giovanna D'Angelo
- Department of Mathematical and Computational Sciences, Physical Science and Earth Science (MIFT), University of Messina, V.le F. Stagno d'Alcontres 31, 98166 Messina, Italy
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2
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Yu CC, Seki T, Chiang KY, Wang Y, Bonn M, Nagata Y. Depth-profiling alkyl chain order in unsaturated lipid monolayers on water. J Chem Phys 2024; 160:114902. [PMID: 38506293 DOI: 10.1063/5.0190519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 02/28/2024] [Indexed: 03/21/2024] Open
Abstract
Unsaturated lipids with C=C groups in their alkyl chains are widely present in the cell membrane and food. The C=C groups alter the lipid packing density, membrane stability, and persistence against lipid oxidation. Yet, molecular-level insights into the structure of the unsaturated lipids remain scarce. Here, we probe the molecular structure and organization of monolayers of unsaturated lipids on the water surface using heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy. We vary the location of the C=C in the alkyl chain and find that at high lipid density, the location of the C=C group affects neither the interfacial water organization nor the tail of the alkyl chain. Based on this observation, we use the C=C stretch HD-SFG response to depth-profile the alkyl chain conformation of the unsaturated lipid. We find that the first 1/3 of carbon atoms from the headgroup are relatively rigid, oriented perpendicular to the surface. In contrast, the remaining carbon atoms can be approximated as free rotators, introducing the disordering of the alkyl chains.
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Affiliation(s)
- Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, 036-8561 Aomori, Japan
| | - Kuo-Yang Chiang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yongkang Wang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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3
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Sepulveda-Montaño LX, Galindo JF, Kuroda DG. Infrared Spectroscopy of Liquid Solutions as a Benchmarking Tool of Semiempirical QM Methods: The Case of GFN2-xTB. J Phys Chem B 2023; 127:7955-7963. [PMID: 37676972 DOI: 10.1021/acs.jpcb.3c03174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
The accurate description of large molecular systems has triggered the development of new computational methods. Due to the computational cost of modeling large systems, the methods usually require a trade-off between accuracy and speed. Therefore, benchmarking to test the accuracy and precision of the method is an important step in their development. The typical gold standard for evaluating these methods is isolated molecules, because of the low computational cost. However, the advent of high-performance computing has made it possible to benchmark computational methods using observables from more complex systems such as liquid solutions. To this end, infrared spectroscopy provides a suitable set of observables (i.e., vibrational transitions) for liquid systems. Here, IR spectroscopy observables are used to benchmark the predictions of the newly developed GFN2-xTB semiempirical method. Three different IR probes (i.e., N-methylacetamide, benzonitrile, and semiheavy water) in solution are selected for this purpose. The work presented here shows that GFN2-xTB predicts central frequencies with errors of less than 10% in all probes. In addition, the method captures detailed properties of the molecular environment such as weak interactions. Finally, the GFN2-xTB correctly assesses the vibrational solvatochromism for N-methylacetamide and semiheavy water but does not have the accuracy needed to properly describe benzonitrile. Overall, the results indicate not only that GFN2-xTB can be used to predict the central frequencies and their dependence on the molecular environment with reasonable accuracy but also that IR spectroscopy data of liquid solutions provide a suitable set of observables for the benchmarking of computational methods.
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Affiliation(s)
| | - Johan Fabian Galindo
- Department of Chemistry, Universidad Nacional de Colombia sede Bogotá, 111321 Bogotá, Colombia
| | - Daniel G Kuroda
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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4
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Malik S, Karmakar S, Debnath A. Quantifying dynamical heterogeneity length scales of interface water across model membrane phase transitions. J Chem Phys 2023; 158:091103. [PMID: 36889951 DOI: 10.1063/5.0137727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
All-atom molecular dynamics simulations of 1,2-dimyristoyl-sn-glycero-3-phosphocholine lipid membranes reveal a drastic growth in the heterogeneity length scales of interface water (IW) across fluid to ripple to gel phase transitions. It acts as an alternate probe to capture the ripple size of the membrane and follows an activated dynamical scaling with the relaxation time scale solely within the gel phase. The results quantify the mostly unknown correlations between the spatiotemporal scales of the IW and membranes at various phases under physiological and supercooled conditions.
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Affiliation(s)
- Sheeba Malik
- Department of Chemistry, IIT Jodhpur, Jodhpur, Rajasthan, India
| | - Smarajit Karmakar
- Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad, India
| | - Ananya Debnath
- Department of Chemistry, IIT Jodhpur, Jodhpur, Rajasthan, India
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5
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Carpenter AP, Khuu P, Weidner T, Johnson CP, Roeters SJ, Baio JE. Orientation of the Dysferlin C2A Domain is Responsive to the Composition of Lipid Membranes. J Phys Chem B 2023; 127:577-589. [PMID: 36608331 DOI: 10.1021/acs.jpcb.2c06716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Dysferlin is a 230 kD protein that plays a critical function in the active resealing of micron-sized injuries to the muscle sarcolemma by recruiting vesicles to patch the injured site via vesicle fusion. Muscular dystrophy is observed in humans when mutations disrupt this repair process or dysferlin is absent. While lipid binding by dysferlin's C2A domain (dysC2A) is considered fundamental to the membrane resealing process, the molecular mechanism of this interaction is not fully understood. By applying nonlinear surface-specific vibrational spectroscopy, we have successfully demonstrated that dysferlin's N-terminal C2A domain (dysC2A) alters its binding orientation in response to a membrane's lipid composition. These experiments reveal that dysC2A utilizes a generic electrostatic binding interaction to bind to most anionic lipid surfaces, inserting its calcium binding loops into the lipid surface while orienting its β-sheets 30-40° from surface normal. However, at lipid surfaces, where PI(4,5)P2 is present, dysC2A tilts its β-sheets more than 60° from surface normal to expose a polybasic face, while it binds to the PI(4,5)P2 surface. Both lipid binding mechanisms are shown to occur alongside dysC2A-induced lipid clustering. These different binding mechanisms suggest that dysC2A could provide a molecular cue to the larger dysferlin protein as to signal whether it is bound to the sarcolemma or another lipid surface.
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Affiliation(s)
- Andrew P Carpenter
- The School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon97331, United States
| | - Patricia Khuu
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon97331, United States
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000Aarhus C, Denmark
| | - Colin P Johnson
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon97331, United States
| | - Steven J Roeters
- Department of Chemistry, Aarhus University, 8000Aarhus C, Denmark
| | - Joe E Baio
- The School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon97331, United States
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6
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Ricchiuti G, Dabrowska A, Pinto D, Ramer G, Lendl B. Dual-Beam Photothermal Spectroscopy Employing a Mach–Zehnder Interferometer and an External Cavity Quantum Cascade Laser for Detection of Water Traces in Organic Solvents. Anal Chem 2022; 94:16353-16360. [DOI: 10.1021/acs.analchem.2c03303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Giovanna Ricchiuti
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9/164-UPA, Vienna1060, Austria
| | - Alicja Dabrowska
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9/164-UPA, Vienna1060, Austria
| | - Davide Pinto
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9/164-UPA, Vienna1060, Austria
| | - Georg Ramer
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9/164-UPA, Vienna1060, Austria
| | - Bernhard Lendl
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9/164-UPA, Vienna1060, Austria
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7
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Yu CC, Seki T, Wang Y, Bonn M, Nagata Y. Polarization-Dependent Sum-Frequency Generation Spectroscopy for Ångstrom-Scale Depth Profiling of Molecules at Interfaces. PHYSICAL REVIEW LETTERS 2022; 128:226001. [PMID: 35714258 DOI: 10.1103/physrevlett.128.226001] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/28/2022] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
The three-dimensional spatial distribution of molecules at soft matter interfaces is crucial for processes ranging from membrane biophysics to atmospheric chemistry. While several techniques can access surface composition, obtaining information on the depth distribution is challenging. We develop a noninvasive, polarization-resolved, surface-specific sum-frequency generation spectroscopy providing quantitative depth information. We demonstrate the technique on formic acid molecules at the air-water interface. With increasing molar fraction from 2.5% to 10%, the formic acid molecules shift, on average, ∼0.9 Å into the bulk. The consistency with the simulation data manifests that the technique allows for probing the Ångstrom-scale depth profile.
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Affiliation(s)
- Chun-Chieh Yu
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Takakazu Seki
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Yongkang Wang
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Mischa Bonn
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Yuki Nagata
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
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8
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Hirano T, Morita A. Boundary effects and quadrupole contribution in sum frequency generation spectroscopy. J Chem Phys 2022; 156:154109. [PMID: 35459322 DOI: 10.1063/5.0076400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Calculation of time correlation functions is a primary task in the computational analysis of sum frequency generation spectroscopy. This paper resolved basic issues to extract interface signals from the calculation. These issues stem from the boundary to restrict the bulk region, which renders the practical computation feasible at a finite and affordable cost. The boundary is found to have significant influences on the time correlation functions, which is closely related to the quadrupole contribution in the nonlinear susceptibility. Thus, we thoroughly examined these influences to establish a proper treatment in performing reliable spectroscopic analysis. We elucidated the distinction of the present boundary effects from the quadrupole contribution and also established a proper center of molecule to minimize the quadrupole effect in the time correlation functions. In the case of liquid water, the proper center was found to be close to the center of mass of a water molecule.
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Affiliation(s)
- Tomonori Hirano
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Akihiro Morita
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
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9
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Yu CC, Imoto S, Seki T, Chiang KY, Sun S, Bonn M, Nagata Y. Accurate molecular orientation at interfaces determined by multimode polarization-dependent heterodyne-detected sum-frequency generation spectroscopy via multidimensional orientational distribution function. J Chem Phys 2022; 156:094703. [DOI: 10.1063/5.0081209] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Many essential processes occur at soft interfaces, from chemical reactions on aqueous aerosols in the atmosphere to biochemical recognition and binding at the surface of cell membranes. The spatial arrangement of molecules specifically at these interfaces is crucial for many of such processes. The accurate determination of the interfacial molecular orientation has been challenging due to the low number of molecules at interfaces and the ambiguity of their orientational distribution. Here, we combine phase- and polarization-resolved sum-frequency generation (SFG) spectroscopy to obtain the molecular orientation at the interface. We extend an exponentially decaying orientational distribution to multiple dimensions, which, in conjunction with multiple SFG datasets obtained from the different vibrational modes, allows us to determine the molecular orientation. We apply this new approach to formic acid molecules at the air–water interface. The inferred orientation of formic acid agrees very well with ab initio molecular dynamics data. The phase-resolved SFG multimode analysis scheme using the multidimensional orientational distribution thus provides a universal approach for obtaining the interfacial molecular orientation.
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Affiliation(s)
- Chun-Chieh Yu
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Sho Imoto
- Analysis Technology Center, Fujifilm R&D, 210 Nakanuma, Minamiashigara, Kanagawa 250-0123, Japan
| | - Takakazu Seki
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Kuo-Yang Chiang
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Shumei Sun
- Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, 100875 Beijing, China
| | - Mischa Bonn
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Yuki Nagata
- Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
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10
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Yılmaz Topuzlu E, Okur HI, Ulgut B, Dag Ö. Role of Water in the Lyotropic Liquid Crystalline Mesophase of Lithium Salts and Non-ionic Surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:14443-14453. [PMID: 34856801 DOI: 10.1021/acs.langmuir.1c02411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The lyotropic liquid crystalline (LLC) mesophase forms upon evaporation of water from aqueous solutions of LiX salts (X is Cl-, Br-, NO3-, or SCN-) and a surfactant [C12H25(OCH2CH2)10OH, abbreviated as C12E10]. The LiX/C12E10/H2O aqueous solutions have been monitored (during evaporation of their excess water to obtain stable LLC mesophases) by gravimetric, spectroscopic, and conductivity measurements to elucidate the role of water in these mesophases. The water/salt molar ratio in stable mesophases changes from 1.5 to 8.0, depending on the counteranion of the salt and the ambient humidity of the laboratory. The LiX/C12E10/H2O LLC mesophases lose water at lower humidity levels and absorb water at higher humidity levels. The LiCl-containing mesophase holds as few as four structural water molecules per LiCl, whereas the LiNO3 mesophase holds 1.5 waters per salt (least among those assessed). This ratio strongly depends on the atmospheric humidity level; the water/LiX mole ratio increases by 0.08 ± 0.01 H2O in the LLC mesophases per percent humidity unit. Surprisingly, the LLC mesophases are stable (no salt leaching) in broad humidity (10-85%) and salt/surfactant mole ratio (2-10 LiX/C12E10) ranges. Attenuated total reflectance Fourier transform infrared spectroscopic data show that the water molecules in the mesophase interact with salt species more strongly in the LiCl mesophase and more weakly in the case of the nitrate ion, which is evident by the shift of the O-H stretching band of water. The O-H stretching peak position in the mesophases decreases in the order νLiCl > νLiBr > νLiSCN > νLiNO3 and accords well with the H2O/LiX mole ratio. The conductivity of the LLC mesophase also responds to the amount of water as well as the nature of the counteranion (X-). The conductivity decreases in the order σLiCl > σLiBr > σLiNO3 > σLiSCN at low salt mole ratios and in the order σLiBr > σLiCl > σLiNO3 > σLiSCN at higher ratios due to structural changes in the mesophase.
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Affiliation(s)
| | - Halil I Okur
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
- UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Burak Ulgut
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
- UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Ömer Dag
- Department of Chemistry, Bilkent University, 06800 Ankara, Turkey
- UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
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11
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Mahdavi-Shakib A, Rich LC, Whittaker TN, Chandler BD. Hydrogen Adsorption at the Au/TiO2 Interface: Quantitative Determination and Spectroscopic Signature of the Reactive Interface Hydroxyl Groups at the Active Site. ACS Catal 2021. [DOI: 10.1021/acscatal.1c04419] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akbar Mahdavi-Shakib
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Lauren C. Rich
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Todd N. Whittaker
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
- Department of Chemical and Biological Engineering, The University of Colorado, Boulder, Colorado 80303, United States
| | - Bert D. Chandler
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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12
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Recent progress of vibrational spectroscopic study on the interfacial structure of biomimetic membranes. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2021. [DOI: 10.1016/j.cjac.2021.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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Vazquez de Vasquez MG, Carter-Fenk KA, McCaslin LM, Beasley EE, Clark JB, Allen HC. Hydration and Hydrogen Bond Order of Octadecanoic Acid and Octadecanol Films on Water at 21 and 1 °C. J Phys Chem A 2021; 125:10065-10078. [PMID: 34761931 DOI: 10.1021/acs.jpca.1c06101] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The temperature-dependent hydration structure of long-chain fatty acids and alcohols at air-water interfaces has great significance in the fundamental interactions underlying ice nucleation in the atmosphere. We present an integrated theoretical and experimental study of the temperature-dependent vibrational structure and electric field character of the immediate hydration shells of fatty alcohol and acid headgroups. We use a combination of surface-sensitive infrared reflection-absorption spectroscopy (IRRAS), surface potentiometry, and ab initio molecular dynamics simulations to elucidate detailed molecular structures of the octadecanoic acid and octadecanol (stearic acid and stearyl alcohol) headgroup hydration shells at room temperature and near freezing. In experiments, the alcohol at high surface concentration exhibits the largest surface potential; yet we observe a strengthening of the hydrogen-bonding for the solvating water molecules near freezing for both the alcohol and the fatty acid IRRAS experiments. Results reveal that the hydration shells for both compounds screen their polar headgroup dipole moments reducing the surface potential at low surface coverages; at higher surface coverage, the polar headgroups become dehydrated, which reduces the screening, correlating to higher observed surface potential values. Lowering the temperature promotes tighter chain packing and an increase in surface potential. IRRAS reveals that the intra- and intermolecular vibrational coupling mechanisms are highly sensitive to changes in temperature. We find that intramolecular coupling dominates the vibrational relaxation pathways for interfacial water determined by comparing the H2O and the HOD spectra. Using ab initio molecular dynamics (AIMD) calculations on cluster systems of propanol + 6H2O and propionic acid + 10H2O, a spectral decomposition scheme was used to correlate the OH stretching motion with the IRRAS spectral features, revealing the effects of intra- and intermolecular coupling on the spectra. Spectra calculated with AIMD reproduce the red shift and increase in intensity observed in experimental spectra corresponding to the OH stretching region of the first solvation shell. These findings suggest that intra- and intermolecular vibrational couplings strongly impact the OH stretching region at fatty acid and fatty alcohol water interfaces. Overall, results are consistent with ice templating behavior for both the fatty acid and the alcohol, yet the surface potential signature is strongest for the fatty alcohol. These findings develop a better understanding of the complex surface potential and spectral signatures involved in ice templating.
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Affiliation(s)
- Maria G Vazquez de Vasquez
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Kimberly A Carter-Fenk
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Laura M McCaslin
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Emma E Beasley
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Jessica B Clark
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Heather C Allen
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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14
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Yu X, Seki T, Yu CC, Zhong K, Sun S, Okuno M, Backus EHG, Hunger J, Bonn M, Nagata Y. Interfacial Water Structure of Binary Liquid Mixtures Reflects Nonideal Behavior. J Phys Chem B 2021; 125:10639-10646. [PMID: 34503330 PMCID: PMC8474108 DOI: 10.1021/acs.jpcb.1c06001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/21/2021] [Indexed: 11/28/2022]
Abstract
The evaporation of molecules from water-organic solute binary mixtures is key for both atmospheric and industrial processes such as aerosol formation and distillation. Deviations from ideal evaporation energetics can be assigned to intermolecular interactions in solution, yet evaporation occurs from the interface, and the poorly understood interfacial, rather than the bulk, structure of binary mixtures affects evaporation kinetics. Here we determine the interfacial structure of nonideal binary mixtures of water with methanol, ethanol, and formic acid, by combining surface-specific vibrational spectroscopy with molecular dynamics simulations. We find that the free, dangling OH groups at the interfaces of these differently behaving nonideal mixtures are essentially indistinguishable. In contrast, the ordering of hydrogen-bonded interfacial water molecules differs substantially at these three interfaces. Specifically, the interfacial water molecules become more disordered (ordered) in mixtures with methanol and ethanol (formic acid), showing higher (lower) vapor pressure than that predicted by Raoult's law.
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Affiliation(s)
- Xiaoqing Yu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Takakazu Seki
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Chun-Chieh Yu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kai Zhong
- University
of Groningen, Zernike Institute
for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Shumei Sun
- Department
of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, 100875 Beijing, China
| | - Masanari Okuno
- Department
of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, 153-8902 Tokyo, Japan
| | - Ellen H. G. Backus
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department
of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Johannes Hunger
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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15
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Moll CJ, Versluis J, Bakker HJ. Direct Evidence for a Surface and Bulk Specific Response in the Sum-Frequency Generation Spectrum of the Water Bend Vibration. PHYSICAL REVIEW LETTERS 2021; 127:116001. [PMID: 34558941 DOI: 10.1103/physrevlett.127.116001] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 05/19/2023]
Abstract
We study the bending mode of pure water and charged aqueous surfaces using heterodyne-detected vibrational sum-frequency generation spectroscopy. We observe a low (1626 cm^{-1}) and a high (1656 cm^{-1}) frequency component that can be unambiguously assigned to an interfacial dipole and a bulk quadrupolar response, respectively. We thus demonstrate that probing the bending mode provides structural and quantitative information on both the surface and the bulk.
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Affiliation(s)
- C J Moll
- AMOLF, Ultrafast Spectroscopy, Science Park 104, 1098XG Amsterdam, Netherlands
| | - J Versluis
- AMOLF, Ultrafast Spectroscopy, Science Park 104, 1098XG Amsterdam, Netherlands
| | - H J Bakker
- AMOLF, Ultrafast Spectroscopy, Science Park 104, 1098XG Amsterdam, Netherlands
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16
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Seki T, Yu CC, Chiang KY, Tan J, Sun S, Ye S, Bonn M, Nagata Y. Disentangling Sum-Frequency Generation Spectra of the Water Bending Mode at Charged Aqueous Interfaces. J Phys Chem B 2021; 125:7060-7067. [PMID: 34159786 PMCID: PMC8279539 DOI: 10.1021/acs.jpcb.1c03258] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 06/05/2021] [Indexed: 12/18/2022]
Abstract
The origin of the sum-frequency generation (SFG) signal of the water bending mode has been controversially debated in the past decade. Unveiling the origin of the signal is essential, because different assignments lead to different views on the molecular structure of interfacial water. Here, we combine collinear heterodyne-detected SFG spectroscopy at the water-charged lipid interfaces with systematic variation of the salt concentration. The results show that the bending mode response is of a dipolar, rather than a quadrupolar, nature and allows us to disentangle the response of water in the Stern and the diffuse layers. While the diffuse layer response is identical for the oppositely charged surfaces, the Stern layer responses reflect interfacial hydrogen bonding. Our findings thus corroborate that the water bending mode signal is a suitable probe for the structure of interfacial water.
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Affiliation(s)
- Takakazu Seki
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Chun-Chieh Yu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kuo-Yang Chiang
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Junjun Tan
- Hefei
National Laboratory for Physical
Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 230026 Hefei, China
| | - Shumei Sun
- Department
of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Shuji Ye
- Hefei
National Laboratory for Physical
Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, 230026 Hefei, China
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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17
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Yamaguchi S, Otosu T. Progress in phase-sensitive sum frequency generation spectroscopy. Phys Chem Chem Phys 2021; 23:18253-18267. [PMID: 34195730 DOI: 10.1039/d1cp01994e] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sum frequency generation (SFG) spectroscopy is a unique and powerful tool for investigating surfaces and interfaces at the molecular level. Phase-sensitive SFG (PS-SFG) is an upgraded technique that can overcome the inherent drawbacks of conventional SFG. Here we review several methods of PS-SFG developed and reported in 1990-2020. We introduce how and by which group each PS-SFG method was designed and built in terms of interferometer implementation for optical heterodyne detection, with one exception of a recent numerical method that does not rely on interferometry. We also discuss how PS-SFG solved some typical problems for aqueous interfaces that were once left open by conventional SFG. These problems and their solutions are good examples to demonstrate why PS-SFG is essential. In addition, we briefly note a few terminology issues related with PS-SFG to avoid confusion.
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Affiliation(s)
- Shoichi Yamaguchi
- Department of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
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18
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Wang R, Klein ML, Carnevale V, Borguet E. Investigations of water/oxide interfaces by molecular dynamics simulations. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2021. [DOI: 10.1002/wcms.1537] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ruiyu Wang
- Department of Chemistry Temple University Philadelphia Pennsylvania USA
- Center for Complex Materials from First Principles (CCM) Temple University Philadelphia Pennsylvania USA
| | - Michael L. Klein
- Department of Chemistry Temple University Philadelphia Pennsylvania USA
- Center for Complex Materials from First Principles (CCM) Temple University Philadelphia Pennsylvania USA
- Institute for Computational Molecular Science, Temple University Philadelphia Pennsylvania USA
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, Temple University Philadelphia Pennsylvania USA
- Department of Biology Temple University Philadelphia Pennsylvania USA
| | - Eric Borguet
- Department of Chemistry Temple University Philadelphia Pennsylvania USA
- Center for Complex Materials from First Principles (CCM) Temple University Philadelphia Pennsylvania USA
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19
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Carpenter AP, Christoffersen EL, Mapile AN, Richmond GL. Assessing the Impact of Solvent Selection on Vibrational Sum-Frequency Scattering Spectroscopy Experiments. J Phys Chem B 2021; 125:3216-3229. [PMID: 33739105 DOI: 10.1021/acs.jpcb.1c00188] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The development of vibrational sum-frequency scattering (S-VSF) spectroscopy has opened the door to directly probing nanoparticle surfaces with an interfacial and chemical specificity that was previously reserved for planar interfacial systems. Despite its potential, challenges remain in the application of S-VSF spectroscopy beyond simplified chemical systems. One such challenge includes infrared absorption by an absorptive continuous phase, which will alter the spectral lineshapes within S-VSF spectra. In this study, we investigate how solvent vibrational modes manifest in S-VSF spectra of surfactant stabilized nanoemulsions and demonstrate how corrections for infrared absorption can recover the spectral features of interfacial solvent molecules. We also investigate infrared absorption for systems with the absorptive phase dispersed in a nonabsorptive continuous phase to show that infrared absorption, while reduced, will still impact the S-VSF spectra. These studies are then used to provide practical recommendations for anyone wishing to use S-VSF to study nanoparticle surfaces where absorptive solvents are present.
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Affiliation(s)
- Andrew P Carpenter
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97405, United States
| | - Evan L Christoffersen
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97405, United States
| | - Ashley N Mapile
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97405, United States
| | - Geraldine L Richmond
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97405, United States
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20
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Golbek TW, Otto SC, Roeters SJ, Weidner T, Johnson CP, Baio JE. Direct Evidence That Mutations within Dysferlin's C2A Domain Inhibit Lipid Clustering. J Phys Chem B 2021; 125:148-157. [PMID: 33355462 DOI: 10.1021/acs.jpcb.0c07143] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mechanical stress on sarcolemma can create small tears in the muscle cell membrane. Within the sarcolemma resides the multidomain dysferlin protein. Mutations in this protein render it unable to repair the sarcolemma and have been linked to muscular dystrophy. A key step in dysferlin-regulated repair is the binding of the C2A domain to the lipid membrane upon increased intracellular calcium. Mutations mapped to this domain cause loss of binding ability of the C2A domain. There is a crucial need to understand the geometry of dysferlin C2A at a membrane interface as well as cell membrane lipid reorientation when compared to that of a mutant. Here, we describe a comparison between the wild-type dysferlin C2A and a mutation to the conserved aspartic acids in the domain binding loops. To identify both the geometry and the cell membrane lipid reorientation, we applied sum frequency generation (SFG) vibrational spectroscopy and coupled it with simulated SFG spectra to observe and quantify the interaction with a model cell membrane composed of phosphotidylserine and phosphotidylcholine. Observed changes in surface pressure demonstrate that calcium-bridged electrostatic interactions govern the initial interaction of the C2A domains docking with a lipid membrane. SFG spectra taken from the amide-I region for the wild type and variant contain features near 1642, 1663, and 1675 cm-1 related to the C2A domain β-sandwich secondary structure, indicating that the domain binds in a specific orientation. Mapping simulated SFG spectra to the experimentally collected spectra indicated that both wild-type and variant domains have nearly the same orientation to the membrane surface. However, examining the ordering of the lipids that make up a model membrane using SFG, we find that the wild type clusters the lipids as seen by the increase in the ratio of the CD3 and CD2 symmetric intensities by 170% for the wild type and by 120% for the variant. This study highlights the capabilities of SFG to probe with great detail biological mutations in proteins at cell membrane interfaces.
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Affiliation(s)
| | - Shauna C Otto
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331, United States
| | - Steven J Roeters
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
| | - Colin P Johnson
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331, United States
| | - Joe E Baio
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, United States
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21
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Yang N, Khuu T, Mitra S, Duong CH, Johnson MA, DiRisio RJ, McCoy AB, Miliordos E, Xantheas SS. Isolating the Contributions of Specific Network Sites to the Diffuse Vibrational Spectrum of Interfacial Water with Isotopomer-Selective Spectroscopy of Cold Clusters. J Phys Chem A 2020; 124:10393-10406. [PMID: 33270448 DOI: 10.1021/acs.jpca.0c07795] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Decoding the structural information contained in the interfacial vibrational spectrum of water requires understanding how the spectral signatures of individual water molecules respond to their local hydrogen bonding environments. In this study, we isolated the contributions for the five classes of sites that differ according to the number of donor (D) and acceptor (A) hydrogen bonds that characterize each site. These patterns were measured by exploiting the unique properties of the water cluster cage structures formed in the gas phase upon hydration of a series of cations M+·(H2O)n (M = Li, Na, Cs, NH4, CH3NH3, H3O, and n = 5, 20-22). This selection of ions was chosen to systematically express the A, AD, AAD, ADD, and AADD hydrogen bonding motifs. The spectral signatures of each site were measured using two-color, IR-IR isotopomer-selective photofragmentation vibrational spectroscopy of the cryogenically cooled, mass selected cluster ions in which a single intact H2O is introduced without isotopic scrambling, an important advantage afforded by the cluster regime. The resulting patterns provide an unprecedented picture of the intrinsic line shapes and spectral complexities associated with excitation of the individual OH groups, as well as the correlation between the frequencies of the two OH groups on the same water molecule, as a function of network site. The properties of the surrounding water network that govern this frequency map are evaluated by dissecting electronic structure calculations that explore how changes in the nearby network structures, both within and beyond the first hydration shell, affect the local frequency of an OH oscillator. The qualitative trends are recovered with a simple model that correlates the OH frequency with the network-modulated local electron density in the center of the OH bond.
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Affiliation(s)
- Nan Yang
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Thien Khuu
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Sayoni Mitra
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Chinh H Duong
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Ryan J DiRisio
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Anne B McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Evangelos Miliordos
- Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352, United States
| | - Sotiris S Xantheas
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.,Advanced Computing, Mathematics and Data Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MS K1-83, Richland, Washington 99352, United States
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22
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Chen M, Li L, Zhu R, Zhu J, He H. Intrinsic water layering next to soft, solid, hydrophobic, and hydrophilic substrates. J Chem Phys 2020; 153:224702. [DOI: 10.1063/5.0030021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Meng Chen
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Institutions of Earth Science, Chinese Academy of Sciences (CAS), Guangzhou 510640, China
| | - Lin Li
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Institutions of Earth Science, Chinese Academy of Sciences (CAS), Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Runliang Zhu
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Institutions of Earth Science, Chinese Academy of Sciences (CAS), Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jianxi Zhu
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Institutions of Earth Science, Chinese Academy of Sciences (CAS), Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongping He
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Institutions of Earth Science, Chinese Academy of Sciences (CAS), Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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23
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Ahmed M, Nihonyanagi S, Kundu A, Yamaguchi S, Tahara T. Resolving the Controversy over Dipole versus Quadrupole Mechanism of Bend Vibration of Water in Vibrational Sum Frequency Generation Spectra. J Phys Chem Lett 2020; 11:9123-9130. [PMID: 33147973 DOI: 10.1021/acs.jpclett.0c02644] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Recently, there has been controversy over whether the HOH bend signal of water in the vibrational sum frequency generation (VSFG) spectrum arises from the conventional dipole mechanism or the quadrupole mechanism. Here, we show that the Im χ(2) (the imaginary part of the second-order nonlinear susceptibility) spectra of the HOH bend mode of water at oppositely charged monolayer/water interfaces all exhibit positive bands, irrespective of the difference in the sign of the charge at the interface. Furthermore, it is found that the peak frequency of the HOH bend band substantially changes depending on the chemical structure of the charged headgroup located at the interface. These results demonstrate that the VSFG signal of the HOH bend vibration is generated from interfacial water with the interfacial quadrupole mechanism that is associated with the large field gradient of incident lights localized in a very thin region at the interface.
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Affiliation(s)
- Mohammed Ahmed
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Satoshi Nihonyanagi
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Achintya Kundu
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Shoichi Yamaguchi
- Department of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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24
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Seki T, Chiang KY, Yu CC, Yu X, Okuno M, Hunger J, Nagata Y, Bonn M. The Bending Mode of Water: A Powerful Probe for Hydrogen Bond Structure of Aqueous Systems. J Phys Chem Lett 2020; 11:8459-8469. [PMID: 32931284 PMCID: PMC7584361 DOI: 10.1021/acs.jpclett.0c01259] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/15/2020] [Indexed: 05/16/2023]
Abstract
Insights into the microscopic structure and dynamics of the water's hydrogen-bonded network are crucial to understand the role of water in biology, atmospheric and geochemical processes, and chemical reactions in aqueous systems. Vibrational spectroscopy of water has provided many such insights, in particular using the O-H stretch mode. In this Perspective, we summarize our recent studies that have revealed that the H-O-H bending mode can be an equally powerful reporter for the microscopic structure of water and provides more direct access to the hydrogen-bonded network than the conventionally studied O-H stretch mode. We discuss the fundamental vibrational properties of the water bending mode, such as the intermolecular vibrational coupling, and its effects on the spectral lineshapes and vibrational dynamics. Several examples of static and ultrafast bending mode spectroscopy illustrate how the water bending mode provides an excellent window on the microscopic structure of both bulk and interfacial water.
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Affiliation(s)
- Takakazu Seki
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kuo-Yang Chiang
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Chun-Chieh Yu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Xiaoqing Yu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Masanari Okuno
- Department
of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan
| | - Johannes Hunger
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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25
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Haroun F, El Haitami A, Ober P, Backus EHG, Cantin S. Poly(ethylene glycol)- block-poly(propylene glycol)- block-poly(ethylene glycol) Copolymer 2D Single Network at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9142-9152. [PMID: 32686418 DOI: 10.1021/acs.langmuir.0c01398] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In this work, Langmuir monolayers based on poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) (PEG-PPG-PEG) triblock copolymer were in situ stabilized at the air-water interface in the presence of a cross-linking agent, benzene-1,3,5-tricarboxaldehyde (BTC), in the aqueous subphase. The reaction takes place through acid-catalyzed acetalization between the terminal hydroxyl groups of the copolymer and aldehyde functions of the BTC molecules. Mean area per repeat unit measurements as a function of the reaction time show a significant monolayer contraction associated with an increase in its compressibility modulus. In addition, Brewster angle microscopy observations indicate the appearance of higher-density two-dimensional domains, irreversibly formed at constant surface pressure. This is also confirmed on a smaller scale by atomic force microscopy (AFM). These arguments, consistent with copolymer monolayer cross-linking in acidic medium, are supported in situ at the air-water interface by sum-frequency generation (SFG) spectroscopy. Furthermore, PEG-PPG-PEG monolayer cross-linking is not evidenced in alkaline medium, in coherence with the interfacial acid-catalyzed acetalization.
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Affiliation(s)
- Ferhat Haroun
- LPPI, CY Cergy Paris Université, F95000 Cergy, France
| | | | - Patrick Ober
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ellen H G Backus
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Sophie Cantin
- LPPI, CY Cergy Paris Université, F95000 Cergy, France
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26
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Venkatraman RK, Baiz CR. Ultrafast Dynamics at the Lipid-Water Interface: DMSO Modulates H-Bond Lifetimes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6502-6511. [PMID: 32423219 DOI: 10.1021/acs.langmuir.0c00870] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Dimethyl sulfoxide (DMSO) is a common cosolvent and cryopreservation agent used to freeze cells and tissues. DMSO alters the H-bond structure of water, but its interactions with biomolecules and, specifically, with biological interfaces remain poorly understood. Here we investigate the effects of DMSO on the H-bond dynamics at the lipid-water interface using a combination of ultrafast two-dimensional infrared (2D IR) spectroscopy and molecular dynamics simulations. Ester carbonyl absorption spectra show that DMSO dehydrates the interface, and simulations show that the area per lipid is decreased. Ultrafast 2D IR spectra measure the time scales of frequency fluctuations at the ester carbonyl positions located precisely between the hydrophobic and hydrophilic regions of the membrane. 2D IR measurements show that low DMSO concentrations (<10 mol %) induce ∼40% faster H-bond dynamics compared with pure water, whereas increased concentrations (>10-20 mol %) once again slow down the dynamics. This slow-fast-slow trend is described in terms of two different solvation regimes. Below 10 mol %, DMSO weakens the interfacial H bond, leading to faster "bulk-like" dynamics, whereas above 10 mol %, water molecules become "relatively immobilized" as the H-bond networks becoming disrupted by the H-bond donor/acceptor imbalance at the interface. These studies are an important step toward characterizing the environments around lipid membranes, which are essential to numerous biological processes.
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Affiliation(s)
- Ravi Kumar Venkatraman
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Carlos R Baiz
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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27
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Wang W, Tan J, Ye S. Unsaturated Lipid Accelerates Formation of Oligomeric β-Sheet Structure of GP41 Fusion Peptide in Model Cell Membrane. J Phys Chem B 2020; 124:5169-5176. [PMID: 32453953 DOI: 10.1021/acs.jpcb.0c02464] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Membrane fusion of the viral and host cell membranes is the initial step of virus infection and is catalyzed by fusion peptides. Although the β-sheet structure of fusion peptides has been proposed to be the most important fusion-active conformation, it is still very challenging to experimentally identify different types of β-sheet structures at the cell membrane surface in situ and in real time. In this work, we demonstrate that the interface-sensitive amide II spectral signals of protein backbones, generated by the sum frequency generation vibrational spectroscopy, provide a sensitive probe for directly capturing the formation of oligomeric β-sheet structure of fusion peptides. Using human immunodeficiency virus (HIV) glycoprotein GP41 fusing peptide (FP23) as the model, we find that formation speed of oligomeric β-sheet structure depends on lipid unsaturation. The unsaturated lipid such as POPG can accelerate formation of oligomeric β-sheet structure of FP23. The β-sheet structure is more deeply inserted into the hydrophobic region of the POPG bilayer than the α-helical segment. This work will pave the way for future researches on capturing intermediate structures during membrane fusion processes and revealing the fusion mechanism.
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Affiliation(s)
- Wenting Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Junjun Tan
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Shuji Ye
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
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28
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Hou J, Sun G, Liu J, Gao X, Zhang X, Lu Z. Liquid/Vapor Interface of Dimethyl Carbonate-Methanol Binary Mixtures Investigated by Sum Frequency Generation Vibrational Spectroscopy and Molecular Dynamics Simulation. J Phys Chem B 2020; 124:4211-4221. [PMID: 32338908 DOI: 10.1021/acs.jpcb.0c01566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present work, the dimethyl carbonate (DMC)-methanol binary mixture was used as a benchmark system to study the molecular structures of the liquid/vapor interface of organic-organic mixtures by sum frequency generation vibrational spectroscopy (SFG-VS) and molecular dynamics (MD) simulations. It was discovered that both the methanol and DMC molecules are anisotropically oriented at the surface, yielding strong SFG-VS signals in the C-H stretching frequency range for both molecules. The detailed analyses of the spectroscopic and MD data reveal that the increase of the methanol bulk concentrations reduces the orientational order of the methyl groups for both the interfacial DMC and methanol molecules but does not significantly affect the orientations of the carbonyl group in DMC. Moreover, no obvious correlations were found between the room-temperature orientations of the surface molecules and the azeotropic mole fraction. The present work paves the road for future investigations on the molecular structures of the liquid/vapor interfaces of other organic-organic mixtures, especially those that are important in industrial separations.
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Affiliation(s)
- Jian Hou
- Beijing National Laboratory for Molecular Sciences and State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guanlun Sun
- School of Chemical Engineering and Technology, National Engineering Research Center of Distillation Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
| | - Jianchuan Liu
- Beijing National Laboratory for Molecular Sciences and State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Gao
- School of Chemical Engineering and Technology, National Engineering Research Center of Distillation Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
| | - Xianyi Zhang
- Anhui Province Key Laboratory of Optoelectronic Material Science and Technology, School of Physics and Electronic Information, Anhui Normal University, Wuhu, Anhui 241002, China
| | - Zhou Lu
- Anhui Province Key Laboratory of Optoelectronic Material Science and Technology, School of Physics and Electronic Information, Anhui Normal University, Wuhu, Anhui 241002, China
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29
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Flanagan JC, Cardenas AE, Baiz CR. Ultrafast Spectroscopy of Lipid-Water Interfaces: Transmembrane Crowding Drives H-Bond Dynamics. J Phys Chem Lett 2020; 11:4093-4098. [PMID: 32364385 DOI: 10.1021/acs.jpclett.0c00783] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Biology takes place in crowded, heterogeneous environments, and it is therefore essential to account for crowding effects in our understanding of biophysical processes at the molecular level. Comparable to the cytosol, proteins occupy approximately 30% of the plasma membrane surface; thus, crowding should have an effect on the local structure and dynamics at the lipid-water interface. Using a combination of ultrafast two-dimensional infrared spectroscopy and molecular dynamics simulations, we quantify the effects of membrane peptide concentration on the picosecond interfacial H-bond dynamics. The measurements reveal a nonmonotonic dependence of water orientation and dynamics as a function of transmembrane peptide:lipid ratio. We observe three dynamical regimes: a "pure lipid-like" regime at low peptide concentrations, a bulk-like region at intermediate peptide concentrations where dynamics are faster by ∼20% compared to those of the pure lipid bilayer, and a crowded regime where high peptide concentrations slow dynamics by ∼50%.
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30
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Artemov VG, Uykur E, Kapralov PO, Kiselev A, Stevenson K, Ouerdane H, Dressel M. Anomalously High Proton Conduction of Interfacial Water. J Phys Chem Lett 2020; 11:3623-3628. [PMID: 32329348 DOI: 10.1021/acs.jpclett.0c00910] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Water at the solid-liquid interface exhibits an anomalous ionic conductivity and dielectric constant compared to bulk water. Both phenomena still lack a detailed understanding. Here, we report radio-frequency measurements and analyses of the electrodynamic properties of interfacial water confined in nanoporous matrices formed by diamond grains of various sizes, ranging from 5 nm to 0.5 μm in diameter. Contrary to bulk water, the charge-carrying protons/holes in interfacial water are not mutually screened, allowing for higher mobility in the external electric field. Thus, the protonic conductivity reaches a maximum value, which can be 5 orders of magnitude higher than that of bulk water. Our results aid in the understanding of physical and chemical properties of water confined in porous materials and pave the way to the development of new type of highly efficient proton-conductive materials for applications in electrochemical energy systems, membrane separations science, and nanofluidics.
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Affiliation(s)
- V G Artemov
- Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - E Uykur
- 1. Physikalisches Institut, Universität Stuttgart, 70569 Stuttgart, Germany
| | | | - A Kiselev
- Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - K Stevenson
- Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - H Ouerdane
- Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - M Dressel
- 1. Physikalisches Institut, Universität Stuttgart, 70569 Stuttgart, Germany
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31
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Seki T, Yu CC, Yu X, Ohto T, Sun S, Meister K, Backus EHG, Bonn M, Nagata Y. Decoding the molecular water structure at complex interfaces through surface-specific spectroscopy of the water bending mode. Phys Chem Chem Phys 2020; 22:10934-10940. [PMID: 32373844 DOI: 10.1039/d0cp01269f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The structure of interfacial water determines atmospheric chemistry, wetting properties of materials, and protein folding. The challenge of investigating the properties of specific interfacial water molecules has frequently been confronted using surface-specific sum-frequency generation (SFG) vibrational spectroscopy using the O-H stretch mode. While perfectly suited for the water-air interface, for complex interfaces, a potential complication arises from the contribution of hydroxyl or amine groups of non-water species present at the surface, such as surface hydroxyls on minerals, or O-H and N-H groups contained in proteins. Here, we present a protocol to extract the hydrogen bond strength selectively of interfacial water, through the water bending mode. The bending mode vibrational frequency distribution provides a new avenue for unveiling the hydrogen bonding structure of interfacial water at complex aqueous interfaces. We demonstrate this method for the water-CaF2 and water-protein interfaces. For the former, we show that this method can indeed single out water O-H groups from surface hydroxyls, and that with increasing pH, the hydrogen-bonded network of interfacial water strengthens. Furthermore, we unveil enhanced hydrogen bonding of water, compared to bulk water, at the interface with human serum albumin proteins, a prototypical bio-interface.
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Affiliation(s)
- Takakazu Seki
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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32
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Tang F, Ohto T, Sun S, Rouxel JR, Imoto S, Backus EHG, Mukamel S, Bonn M, Nagata Y. Molecular Structure and Modeling of Water-Air and Ice-Air Interfaces Monitored by Sum-Frequency Generation. Chem Rev 2020; 120:3633-3667. [PMID: 32141737 PMCID: PMC7181271 DOI: 10.1021/acs.chemrev.9b00512] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Indexed: 12/26/2022]
Abstract
From a glass of water to glaciers in Antarctica, water-air and ice-air interfaces are abundant on Earth. Molecular-level structure and dynamics at these interfaces are key for understanding many chemical/physical/atmospheric processes including the slipperiness of ice surfaces, the surface tension of water, and evaporation/sublimation of water. Sum-frequency generation (SFG) spectroscopy is a powerful tool to probe the molecular-level structure of these interfaces because SFG can specifically probe the topmost interfacial water molecules separately from the bulk and is sensitive to molecular conformation. Nevertheless, experimental SFG has several limitations. For example, SFG cannot provide information on the depth of the interface and how the orientation of the molecules varies with distance from the surface. By combining the SFG spectroscopy with simulation techniques, one can directly compare the experimental data with the simulated SFG spectra, allowing us to unveil the molecular-level structure of water-air and ice-air interfaces. Here, we present an overview of the different simulation protocols available for SFG spectra calculations. We systematically compare the SFG spectra computed with different approaches, revealing the advantages and disadvantages of the different methods. Furthermore, we account for the findings through combined SFG experiments and simulations and provide future challenges for SFG experiments and simulations at different aqueous interfaces.
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Affiliation(s)
- Fujie Tang
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physics, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Tatsuhiko Ohto
- Graduate
School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Shumei Sun
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Jérémy R. Rouxel
- Department
of Chemistry and Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Sho Imoto
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Ellen H. G. Backus
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Shaul Mukamel
- Department
of Chemistry and Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Yuki Nagata
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physics, State Key Laboratory of Surface Physics and Key Laboratory
of Micro- and Nano-Photonic Structures (MOE), Fudan University, Shanghai 200433, China
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33
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Sun S, Schaefer J, Backus EHG, Bonn M. How surface-specific is 2nd-order non-linear spectroscopy? J Chem Phys 2019; 151:230901. [PMID: 31864247 DOI: 10.1063/1.5129108] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Surfaces and interfaces play important roles in many processes and reactions and are therefore intensively studied, often with the aim of obtaining molecular-level information from just the interfacial layer. Generally, only the first few molecular layers next to the interface are relevant for the surface processes. In the past decades, 2nd-order nonlinear spectroscopies including sum-frequency generation and second harmonic generation have developed into powerful tools for obtaining molecularly specific insights into the interfacial region. These approaches have contributed substantially to our understanding of a wide range of physical phenomena. However, along with their wide-ranging applications, it has been realized that the implied surface-specificity of these approaches may not always be warranted. Specifically, the bulk quadrupole contribution beyond the electric dipole-approximation for a system with a weak nonlinear interface signal, as well as the diffuse layer contribution at charged interfaces, could mask the surface information. In this perspective paper, we discuss the surface-specificity of 2nd-order nonlinear spectroscopy, especially considering these two contributions.
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Affiliation(s)
- Shumei Sun
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Jan Schaefer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ellen H G Backus
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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