Surface Enhancement in Ultrafast 2D ATR IR Spectroscopy at the Metal-Liquid Interface

Kraack, Jan Philip; Kaech, Andres; Hamm, Peter

doi:10.1021/acs.jpcc.5b11051

Cited by 57 publications

(131 citation statements)

References 94 publications

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“…While the linear ATR absorption spectrum scales as μ 2 , the 2D ATR IR spectrum scales as μ 4 . Comparing both spectra, one can therefore determine the relative absorption cross sections

μ_{{CN}^{-}}^{2} / μ_{CO}^{2} \approx 0.5

without having to know the surface coverage of either CO or CN − 50,73,74 . The absorption cross section thus accounts for the reduced overall absorption of CN − (Figure 1(b)) only partially and the remaining factor (0.6) must reflect a lower surface coverage of CN − , despite the fact that the surface is saturated under the employed conditions.…”

Section: D Atr Ir Resultsmentioning

confidence: 99%

Molecule-specific interactions of diatomic adsorbates at metal-liquid interfaces

Kraack

Kaech

Hamm

2017

Structural Dynamics

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Ultrafast vibrational dynamics of small molecules on platinum (Pt) layers in water are investigated using 2D attenuated total reflectance IR spectroscopy. Isotope combinations of carbon monoxide and cyanide are used to elucidate inter-adsorbate and substrate-adsorbate interactions. Despite observed cross-peaks in the CO spectra, we conclude that the molecules are not vibrationally coupled. Rather, strong substrate-adsorbate interactions evoke rapid (∼2 ps) vibrational relaxation from the adsorbate into the Pt layer, leading to thermal cross-peaks. In the case of CN, vibrational relaxation is significantly slower (∼10 ps) and dominated by adsorbate-solvent interactions, while the coupling to the substrate is negligible.

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“…While the linear ATR absorption spectrum scales as μ 2 , the 2D ATR IR spectrum scales as μ 4 . Comparing both spectra, one can therefore determine the relative absorption cross sections

μ_{{CN}^{-}}^{2} / μ_{CO}^{2} \approx 0.5

Section: D Atr Ir Resultsmentioning

confidence: 99%

Molecule-specific interactions of diatomic adsorbates at metal-liquid interfaces

Kraack

Kaech

Hamm

2017

Structural Dynamics

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“…292,293 Surface-enhanced 2D IR has been recently demonstrated using an ATR optical geometry. 294–296 Additionally, the combination of 2D IR with plasmonic nanostructures 297,298 promises to expand the technique’s impact by probing even smaller sample volumes and opening the door to vibrational modes with weaker oscillator strengths.…”

Section: Discussionmentioning

confidence: 99%

Watching Proteins Wiggle: Mapping Structures with Two-Dimensional Infrared Spectroscopy

2017

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Proteins exhibit structural fluctuations over decades of time scales. From the picosecond side chain motions to aggregates that form over the course of minutes, characterizing protein structure over these vast lengths of time is important to understanding their function. In the past 15 years, two-dimensional infrared spectroscopy (2D IR) has been established as a versatile tool that can uniquely probe proteins structures on many time scales. In this review, we present some of the basic principles behind 2D IR and show how they have, and can, impact the field of protein biophysics. We highlight experiments in which 2D IR spectroscopy has provided structural and dynamical data that would be difficult to obtain with more standard structural biology techniques. We also highlight technological developments in 2D IR that continue to expand the scope of scientific problems that can be accessed in the biomedical sciences.

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“…[25][26][27] The surface coverage of various co-adsorbates at the catalytic solid-liquid interface under reaction conditions, and more importantly, even during the hydrogenation (operando) has not been accessible with existing techniques.…”

Section: Introductionmentioning

confidence: 99%

The Critical Role of Tilted Cinchona Surface Species for Enantioselective Hydrogenation

et al. 2017

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On chirally-modified metal catalysts enantioselectivity is controlled by the molecular orientation of adsorbates at the chiral catalytic solid-liquid interface. To gain information on the surface coverage and to assess the enantioselecting ability of chiral modifiers depending on their molecular orientation we employed an operando spectroscopic technique using attenuated total reflection-IR and UV-Vis spectroscopies. Our study reveals that the enantiodifferentiation of the cinchona chiral modifier cinchonine varies significantly depending on its adsorption mode. In contrast to the prevailing mechanistic models, which imply that the most stable surface species is responsible for enantiodifferentiation, our results show that less stable cinchona species with a tilted aromatic ring anchor provide significantly stronger enantioselective control. As a consequence the so-called anchoring moiety of the chiral modifier exceeds the mere function of adsorptive anchoring and its molecular orientation has to be also taken into account in explaining the observed enantioselectivity of chirally-modified metals.

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Surface Enhancement in Ultrafast 2D ATR IR Spectroscopy at the Metal-Liquid Interface

Cited by 57 publications

References 94 publications

Molecule-specific interactions of diatomic adsorbates at metal-liquid interfaces

Molecule-specific interactions of diatomic adsorbates at metal-liquid interfaces

Watching Proteins Wiggle: Mapping Structures with Two-Dimensional Infrared Spectroscopy

The Critical Role of Tilted Cinchona Surface Species for Enantioselective Hydrogenation

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