Chemical Imaging of Monolayers on Metal Surfaces: Applications in Corrosion, Catalysis, and Self‐Assembled Monolayers

Baldelli, Steven

doi:10.1002/cphc.200800501

Cited by 14 publications

(12 citation statements)

References 59 publications

(58 reference statements)

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“…In recent years, nonlinear microscopy has been used to image biological systems. This can be done using fluorophores, whereby the two-photon fluorescence or SHS signals are imaged (115,116). It is also possible to use nanoparticles for imaging, and work is being done to develop nanoparticles that can link specifically to biological markers (117,118).…”

Section: Biological Applicationsmentioning

confidence: 99%

Nonlinear Light Scattering and Spectroscopy of Particles and Droplets in Liquids

Roke

Gonella

2012

Annu. Rev. Phys. Chem.

230

286

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Nano- and microparticles have optical, structural, and chemical properties that differ from both their building blocks and the bulk materials themselves. These different physical and chemical properties are induced by the high surface-to-volume ratio. As a logical consequence, to understand the properties of nano- and microparticles, it is of fundamental importance to characterize the particle surfaces and their interactions with the surrounding medium. Recent developments of nonlinear light scattering techniques have resulted in a deeper insight of the underlying light-matter interactions. They have shed new light on the molecular mechanism of surface kinetics in solution, properties of interfacial water in contact with hydrophilic and hydrophobic particles and droplets, molecular orientation distribution of molecules at particle surfaces in solution, interfacial structure of surfactants at droplet interfaces, acid-base chemistry on particles in solution, and vesicle structure and transport properties.

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Section: Biological Applicationsmentioning

confidence: 99%

Nonlinear Light Scattering and Spectroscopy of Particles and Droplets in Liquids

Roke

Gonella

2012

Annu. Rev. Phys. Chem.

230

286

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“…Our approach builds on these studies but instead focuses on tailor-made interfaces and the chemical selectivity underlying these reactive surfaces. Of particular relevance here are pioneering studies probing chemical reactions at metallic − and semiconducting − interfaces. Only somewhat more recently have reports appeared probing well-defined catalytic semiconductor oxide interfaces with a single exposed facet.…”

Section: Introductionmentioning

confidence: 99%

Absolute Molecular Orientation of Isopropanol at Ceria (100) Surfaces: Insight into Catalytic Selectivity from the Interfacial Structure

Doughty¹,

Srinivasan

Bryantsev³

et al. 2017

J. Phys. Chem. C

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The initial mechanistic steps underlying heterogeneous chemical catalysis can be described in a framework where the composition, structure, and orientation of molecules adsorbed to reactive interfaces are known. However, extracting this vital information is the limiting step in most cases due in part to challenges in probing the interfacial monolayer with enough chemical specificity to characterize the surface molecular constituents. These challenges are exacerbated at complex or spatially heterogeneous interfaces where competing processes and a distribution of local environments can uniquely drive chemistry. To address these limitations, this work presents a distinctive combination of materials synthesis, surface-specific optical experiments, and theory to probe and understand molecular structure at catalytic interfaces. Specifically, isopropanol was adsorbed to surfaces of the model CeO2 catalyst that were synthesized with only the (100) facet exposed. Vibrational sum-frequency generation was used to probe the molecular monolayer and, with the guidance of density functional theory calculations, was used to extract the structure and absolute molecular orientation of isopropanol at the CeO2(100) surface. Our results show that isopropanol is readily deprotonated at the surface, and through the measured absolute molecular orientation of isopropanol, we obtain new insight into the selectivity of the (100) surface to form propylene. Our findings reveal key insight into the chemical and physical phenomena taking place at pristine interfaces, thereby pointing to intuitive structural arguments to describe catalytic selectivity in more complex systems.

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“…Therefore, SFG spectroscopy depends on intense pulsed lasers for input and extremely sensitive detectors for output. Still, SFG spectroscopy has delivered remarkable results and its abilities for surface chemistry have been summarized in several publications. ,− Due to these qualities, SFG has been particularly useful for characterizing self-assembled monolayers, surfactants, ionic liquid interfaces, solid–air interfaces, and many other systems. ,,, …”

Section: Introductionmentioning

confidence: 99%

Chemical Imaging of Surfaces with Sum Frequency Generation Vibrational Spectroscopy

Shah

Baldelli

2020

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Surface chemistry is a key area of study in the chemical sciences, and many system properties are dominated by the chemistry at the interface between two bulk media. While the interface may have a large influence on the system behavior, there are relatively few molecules at the interface compared to the bulk; thus, probing their unique properties has become a specialized field in physical chemistry. In addition to the heterogeneous phase chemistry, surfaces also present spatial heterogeneity (Chemistry in Two Dimensions). This 2D chemistry affects the properties as much as the heterogeneous phases. If we consider the Cartesian z-axis as defining the dimension across the interface between the two bulk phases, then the x−y plane is the 2D region of the surface. We might even consider that the majority of surface chemistry has been concerned with this z-dimension, i.e., surface structure, partition excess, thermodynamics, etc. relative to the bulk, where the 2D distribution was only considered on average. This treatment is understandable since few techniques provide the spatial and chemical resolution needed to deduce the effects of 2D heterogeneity on the surface properties. It is desirable to use an all-optical technique for interface studies because the optical methods provide the chemical specificity through spectroscopy. Also, the use of second-order spectroscopy is typically surface-sensitive without background subtractions or enhancement mechanisms that could limit the range of systems to be investigated. In this Account, the development and selected results of sum frequency generation microscopy and its contributions to the surface chemistry are presented. Sum frequency generation (SFG) provides a unique probe for studying surface chemistry in ambient conditions with surface specificity. SFG provides image contrast based on multiplechemically importantmechanisms such as chemical functional groups, molecular orientation, surface concentration, molecular conformation, local electric fields, among others.To understand the spatial distribution of heterogeneous chemistry, multiple microscopy methods have been developed which utilize the SFG process to yield spatial information with chemical sensitivity. These spectroscopic-microscopies come with unique advantages as well as challenges. Multiple solutions have been developed in this field to overcome the challenges and improve the advantages. In this Account, some of the leading SFG surface microscopies for surface studies are introduced. Initially, direct imaging of the SFG signal onto a CCD camera provided spatially and spectrally resolved imaging of monolayers on surfaces. However, to speed up the imaging process, the technique of compressive sensing was applied to SFG imaging. Most recently the use of machine learning methods and target factor analysis have improved the quality and acquisition speed of SFG images.

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Chemical Imaging of Monolayers on Metal Surfaces: Applications in Corrosion, Catalysis, and Self‐Assembled Monolayers

Cited by 14 publications

References 59 publications

Nonlinear Light Scattering and Spectroscopy of Particles and Droplets in Liquids

Nonlinear Light Scattering and Spectroscopy of Particles and Droplets in Liquids

Absolute Molecular Orientation of Isopropanol at Ceria (100) Surfaces: Insight into Catalytic Selectivity from the Interfacial Structure

Chemical Imaging of Surfaces with Sum Frequency Generation Vibrational Spectroscopy

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