Introduction to Quantitative Data Analysis in Vibrational Sum-Frequency Generation Spectroscopy

Hofmann, Matthias J.; Koelsch, Patrick

doi:10.1007/978-3-319-24502-7_15

Cited by 3 publications

(5 citation statements)

References 34 publications

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“…We have also highlighted the possibility of obtaining qualitative information from SFG spectra. This represents a shift for the nonlinear vibrational spectroscopy community, where it has been established that the study of small molecules with known composition can yield remarkable quantitative detail about orientation, conformation, and the surface orientation distribution. , In contrast, by examining trends in spectral intensity changes, SFG spectra can be used to obtain information about changes occurring in the interfacial environment. Even in cases where detailed analysis of vibrational modes is not performed, optical effects such as local field corrections are critical and must be considered.…”

Section: Discussionmentioning

confidence: 99%

Surface Water as a Mediator and Reporter of Adhesion at Aqueous Interfaces

2018

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Understanding the adsorption of molecules onto surfaces is integral to a wide variety of fields with scientific, engineering, and industrial applications. The surface-adsorbed structure is governed by the nature of the molecule, surface characteristics, and solution environment. There are therefore three critical interactions that govern adhesion: solvent-analyte, substrate-analyte, and substrate-solvent. The last two interactions require a surface-specific probe restricted to a few nanometers or less. This is particularly true of efforts to probe polymer surface structure without being overwhelmed by bulk polymer signal or interfacial water structure in the presence of bulk water. Second-order nonlinear optical techniques are ideal probes of such interactions, as their reporting depth is determined by the polar arrangement of molecules (a break in the macroscopic inversion symmetry) rather than the penetration of the optical fields. This Account begins with an introduction of surface water structure from the perspective of a nonlinear probe. Details about the unique view of the water orientation distribution are discussed and contrasted with information obtained from conventional vibrational techniques. The salient features of water next to model hydrophobic and hydrophilic surfaces are discussed, in preparation for a discussion of solute interactions that follows. We then present three examples using a combination of linear and nonlinear vibrational spectroscopy and molecular dynamics simulations to illustrate how water is both a mediator and a marker of adhesion. The first is a study of amphipathic peptide adhesion onto hydrophobic and hydrophilic surfaces, characterizing the adsorbed structure in relation to the water surrounding the molecule and trapped near the surface. Water is found to be especially important in mediating adhesion to hydrophilic surfaces, where it aids in solvating the peptide as well as facilitating interactions with the surface. In the second example, we look at adhesion of a multicomponent polymer adhesive using surface-bulk heterospectral correlation analysis, in which surface vibrational spectroscopy is combined with bulk infrared absorption to determine interfacial structure development during the evaporation of water. When acrylic acid is added to the polymer, there is a change in orientation of the polymer before an increase in population. This is opposite to what is observed when no additive is present. In our third example, we show how interfacial water provides a unique window into the surface microenvironment during bacterial adhesion, highlighting the role of solution conditions at the surface in cell attachment and biofilm growth. Changes in the nonlinear vibrational response of interfacial water reflect changes occurring in the pH and ionic strength only at the surface, due to the presence of polymeric adhesives secreted by the bacteria. These studies underline the importance of surface water in governing the structure of adhered molecules and in mediating changes in the in...

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Section: Discussionmentioning

confidence: 99%

Surface Water as a Mediator and Reporter of Adhesion at Aqueous Interfaces

2018

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“…When the IR light is exciting vibrational states that are both IR and Raman active, SFG signals are resonantly enhanced. 30 …”

Section: Experimental Insights Into the Switching Mechanismmentioning

confidence: 99%

“…When the IR light is exciting vibrational states that are both IR and Raman active, SFG signals are resonantly enhanced. 30 SFG allows the observation of biotin orientations in the biotin-4KC:TEGT SAM in response to an applied potential by taking advantages of even-order nonlinear optical selection rules that precludes signals from isotropic environments or molecular arrangements that possess inversion symmetry. 31 A first attempt to study molecular changes in the biotin-4KC:TEGT SAM was performed by using a purpose built electrochemical cell that allows to measurement of SFG spectra while applying an electrical potential.…”

Section: Experimental Insights Into the Switching Mechanismmentioning

confidence: 99%

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Electrically Responsive Surfaces: Experimental and Theoretical Investigations

Cantini¹,

Wang

Koelsch

et al. 2016

Acc. Chem. Res.

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ConspectusStimuli-responsive surfaces have sparked considerable interest in recent years, especially in view of their biomimetic nature and widespread biomedical applications. Significant efforts are continuously being directed at developing functional surfaces exhibiting specific property changes triggered by variations in electrical potential, temperature, pH and concentration, irradiation with light, or exposure to a magnetic field. In this respect, electrical stimulus offers several attractive features, including a high level of spatial and temporal controllability, rapid and reverse inducement, and noninvasiveness. In this Account, we discuss how surfaces can be designed and methodologies developed to produce electrically switchable systems, based on research by our groups. We aim to provide fundamental mechanistic and structural features of these dynamic systems, while highlighting their capabilities and potential applications. We begin by briefly describing the current state-of-the-art in integrating electroactive species on surfaces to control the immobilization of diverse biological entities. This premise leads us to portray our electrically switchable surfaces, capable of controlling nonspecific and specific biological interactions by exploiting molecular motions of surface-bound electroswitchable molecules. We demonstrate that our self-assembled monolayer-based electrically switchable surfaces can modulate the interactions of surfaces with proteins, mammalian and bacterial cells. We emphasize how these systems are ubiquitous in both switching biomolecular interactions in highly complex biological conditions while still offering antifouling properties. We also introduce how novel characterization techniques, such as surface sensitive vibrational sum-frequency generation (SFG) spectroscopy, can be used for probing the electrically switchable molecular surfaces in situ. SFG spectroscopy is a technique that not only allowed determining the structural orientation of the surface-tethered molecules under electroinduced switching, but also provided an in-depth characterization of the system reversibility. Furthermore, the unique support from molecular dynamics (MD) simulations is highlighted. MD simulations with polarizable force fields (FFs), which could give proper description of the charge polarization caused by electrical stimulus, have helped not only back many of the experimental observations, but also to rationalize the mechanism of switching behavior. More importantly, this polarizable FF-based approach can efficiently be extended to light or pH stimulated surfaces when integrated with reactive FF methods. The interplay between experimental and theoretical studies has led to a higher level of understanding of the switchable surfaces, and to a more precise interpretation and rationalization of the observed data. The perspectives on the challenges and opportunities for future progress on stimuli-responsive surfaces are also presented.

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“…102 A análise quantitativa e qualitativa dos espectros SFG é complexa devido à forma de linha peculiar que as ressonâncias podem assumir devido aos efeitos de interferência entre picos vizinhos e entre sinais ressonantes e não ressonantes, e pode ser encontrada detalhadamente em alguns trabalhos recentes. [103][104] Vimos que a expressão aproximada para χ (2) , tomada no caso em que a frequência no IR é próxima de uma ressonância vibracional e a visível é distante das frequências de transição eletrônica (Equação (18)), pode ser reescrita como:  , considerando apenas um pico simples com ressonância arbitrária em 3000 cm -1 .…”

Section: Forma De Linha Dos Espectros -Modelo Lorentzianounclassified

Estudo da adsorção de monocamadas de água em gipsita(010) através de óptica não linear

Santos¹

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Introduction to Quantitative Data Analysis in Vibrational Sum-Frequency Generation Spectroscopy

Cited by 3 publications

References 34 publications

Surface Water as a Mediator and Reporter of Adhesion at Aqueous Interfaces

Surface Water as a Mediator and Reporter of Adhesion at Aqueous Interfaces

Electrically Responsive Surfaces: Experimental and Theoretical Investigations

Estudo da adsorção de monocamadas de água em gipsita(010) através de óptica não linear

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