Optical Spectroscopy of Surfaces, Interfaces, and Thin Films: A Status Report

Watts, Kristen E.; Blackburn, Thomas J.; Pemberton, Jeanne E.

doi:10.1021/acs.analchem.9b00735

Cited by 15 publications

(11 citation statements)

References 231 publications

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“…VSFG employs a broadband IR pulse (290 fs duration) centered at ~2850 cm -1 to excite CH vibrational modes of the SDS@2β-CD system, which is followed by a narrowband 1025nm near IR pulse to upcovert the vibrational coherence to a higher frequency macroscopic polarization emitted as the VSFG signal. As an even-order nonlinear optical process, only noncentrosymmetric systems produce VSFG responses, such as the air/liquid, air/solid and solid/liquid interfaces 29,31,[40][41][42][32][33][34][35][36][37][38][39] with a powerful demonstration of the techniques capabilities found in its application to the air/water interface. [43][44][45] Another class of systems that can be studied by VSFG that have not been paid much attention are materials without inversion centers.…”

Section: Linescanning Vsfg Imagingmentioning

confidence: 99%

Imaging Orientation of a Single Molecular Hierarchical Self-Assembled Sheet: The Combined Power of a Vibrational Sum Frequency Generation Microscopy and Neural Network

Wagner

Xiong

2022

Preprint

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In this work, we determined the tilt angles of molecular units in hierarchical self-assembled materials on a single-sheet level, which were not available previously. This was achieved by developing a fast linescanning vibrational sum frequency generation (VSFG) hyperspectral imaging technique in combination with neural network analysis. Rapid VSFG imaging enables polarization resolved images on a single sheet level to be measured within a short time period, circumventing technical challenges due to long term optical setup instability. The polarization resolved hyperspectral images were then used to extract the supramolecular tilt angle of a self-assembly through a set of spectra-tilt angle relationships which were solved through neural network techniques. This unique combination of both novel techniques offers a new pathway to resolve molecular level structural knowledge of self-assembled materials. Understanding these properties can further drive self-assembly design from a bottom-up approach for applications in biomimetic and drug delivery researches.

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Section: Linescanning Vsfg Imagingmentioning

confidence: 99%

Imaging Orientation of a Single Molecular Hierarchical Self-Assembled Sheet: The Combined Power of a Vibrational Sum Frequency Generation Microscopy and Neural Network

Wagner

Xiong

2022

Preprint

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“…The advances of IR spectral imaging have thus been pushed over years, and as a mature technique, there are many types of Fourier‐transform infrared spectroscopy (FTIR)‐based commercial products. Currently, the developing trend of IR spectral imaging involves the maximizing of spatial resolution, the improving of image acquisition speed, and the understanding of obtained data …”

Section: Spectroscopic Imagingmentioning

confidence: 99%

“…The development and applications of AFM‐IR have been reviewed in the fields of polymers, cells and tissues, and energy materials . As for the main discussion of 2D materials in this review, IR spectroscopic mapping has also been responsible for the findings of many unique properties such as thickness measurement and plasmonics and now has become an indispensable analytical tool . For example, a s‐SNOM with synchrotron radiation was utilized for plasmonic property study of single‐layer and double‐layer MoS 2 grown by CVD method, showing the ability to detect distinctly local excitations .…”

Section: Spectroscopic Imagingmentioning

confidence: 99%

Microscale Spectroscopic Mapping of 2D Optical Materials

Dong

Yetisen

Köhler

et al. 2019

Advanced Optical Materials

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be used for flexible touch screens and displays, printable electronics, and thinfilm photovoltaics, [4] while FETs made of graphene can be used for highly sensitive biosensors. [5] Another 2D material MoS 2 , a direct-bandgap semiconductor, has applications in ultrasensitive photodetectors, transistors, and gas-sensing devices. [6][7][8][9] Other 2D materials have also shown potential in photovoltaic devices, memory, and light-emitting diodes (LEDs). [10,11] Broad application potential of 2D materials in optoelectronic devices, photonic devices, and optical sensors is mainly based on their unique optical performances. [12] 2D materials can be fabricated based on their layered structure. In the molecular structures of these materials, the atoms are bonded hard in the same plane, but the bond effect between two lateral layers is weak due to van der Waals forces. [13] 2D materials can be roughly categorized as semimetal like graphene, semiconductor like transition metal dichalcogenides (TMDs), and insulator like hexagonal boron nitride (hBN) from the aspect of bandgap differences. [14] Due to the experimentally practical manipulation of monolayer and multilayer 2D materials, remarkable optical performances can be realized for a wide range of optical applications. For example, the number of layers of 2D materials can strongly influence the photoluminescence performance. [15] The unconventional optical performances including adsorption and emission, light sensitivity, as well as plasmonic effects of 2D materials are closely related to their inner physical properties such as carrier mobility, density of states, and band structure based on the interaction of atoms, structural symmetry, and stacking patterns. [16,17] Through the control of layer number which could influence the bandgap value, 2D materials could react to different spectrum ranging from ultraviolet to infrared light. [18] Doping strategies are also effective to modify intrinsic 2D semiconductors and improve the response with respect to an extended range of spectrum. [19,20] The assessment of the optical properties of 2D materials is indispensable for device and sensor development. [21] Based on detailed surface mapping and spectral information, the suitability of 2D materials for optical devices or sensor applications can be thoroughly studied. [22,23] Microscopy, direct 2D mapping of materials, can provide basic spatial information, [24] while spectroscopy can offer one more dimensional spectral information which is 2D materials have unique optical properties due to their ultrathin layered structures, and are emerging as promising materials for optoelectronic devices. To characterize and evaluate these properties, diffraction-limited spectroscopic mapping, also known as microscale spectroscopic imaging, has been developed to provide abundant spatial and spectral information. The usefulness of microscale spectroscopic mapping for unique property study of 2D optical materials is addressed. Advances in both mature and growing microscale spectroscopic mapping...

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“…6 Even in the ideal case of a perfectly planar surface in contact with a liquid, intermolecular interactions lead to highly nonideal regions of the fluid phase. 7 Measuring the properties and structure of this interfacial region is challenging and often requires specialist experimental techniques [8][9][10][11][12] This is compounded in the case of changing or fluctuating surfaces. Crystal growth is a paradigmatic example of such a macroscopic process emerging from the collective behavior of a large number of molecules and the evolution of a solid/liquid interface.…”

Section: Introductionmentioning

confidence: 99%

Bridging the gap between mesoscopic and molecular models of solid/liquid interfaces out-of-equilibrium

Finney¹,

Salvalaglio²

2021

Preprint

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Solid/liquid interfaces control various processes of technological relevance in the process industry and many fundamental physicochemical phenomena. This work examines the link between the atomistic description of mass transfer at solid/liquid interfaces out of equilibrium and the constitutive mass transfer equations typically used to model these processes at the mesoscale. In our analysis we discuss the microscopic inconsistencies apparent in simplified models of mass transfer whenever non-idealities dominate the liquid phase in the proximity of solid/liquid interfaces. Using CµMD -a molecular simulation technique to investigate out-ofequilibrium, concentration-driven processes with pseudo open-boundary conditions -we outline a strategy to capture and quantify non-idealities induced by specific interactions between the solid surface and molecules in the fluid phase. We demonstrate our approach by studying electrolyte solutions in technologically important, multi-component systems in which introducing a solid/liquid interface induces substantial deviations in the composition and electrochemical properties compared to the fluid phase bulk. To this aim, we analyse NaCl(aq) solutions in contact with i ) the graphite basal surface and ii ) {100}) NaCl(s) crystalline surfaces. We uncover the tendency of the sodium cation to preferentially adsorb at the surfaces considered, which induces local violations of electroneutrality that leads to the emergence of an electric potential in the fluid phase at the solid/liquid interface.

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Optical Spectroscopy of Surfaces, Interfaces, and Thin Films: A Status Report

Cited by 15 publications

References 231 publications

Imaging Orientation of a Single Molecular Hierarchical Self-Assembled Sheet: The Combined Power of a Vibrational Sum Frequency Generation Microscopy and Neural Network

Imaging Orientation of a Single Molecular Hierarchical Self-Assembled Sheet: The Combined Power of a Vibrational Sum Frequency Generation Microscopy and Neural Network

Microscale Spectroscopic Mapping of 2D Optical Materials

Bridging the gap between mesoscopic and molecular models of solid/liquid interfaces out-of-equilibrium

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