Quadrupole Contributions from Interface and Bulk

Morita, Akihiro

doi:10.1007/978-981-13-1607-4_7

Cited by 4 publications

(1 citation statement)

References 20 publications

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“…SFG can selectively detect CNCs at the interface. In the reflection detection geometry as shown in Figure a, the SFG coherence length is calculated to be ∼45 nm. , The SFG signal from CNCs in the bulk phase of the aqueous solution is too weak to be considered as the concentration is very low (0.01 wt %). The SFG measurement is sensitive to only the chiral components of small molecules at the psp (p, polarized SFG; s, polarized VIS; p, polarized IR) polarization combination and achiral components at the ssp polarization combination. , Cellulose Iβ is active in both chiral and achiral combinations of the SFG polarizations, while alkyl chains in DODA are active only in the achiral polarization. − This principle was exploited to distinguish between SFG signals from CNC and DODA at the interface (Figure b,c). ,,− In the psp-SFG spectrum, the 2850 and 2944 cm –1 peaks are attributed to the CH/CH 2 stretching modes of CNC Iβ, and the 3338 cm –1 peak is assigned to the OH stretching mode of CNC. , In the ssp-SFG spectrum, the 2848 and 2872 cm –1 peaks are assigned to CH 2 ( d + ) and CH 3 ( r + ) symmetric stretching modes of DODA, respectively. , The 2920 cm –1 peak can be assigned to the Fermi resonance (FR) of CH 2 ( d + -FR) of DODA .…”

Section: Resultsmentioning

confidence: 99%

Compression-Induced Topographic Corrugation of Air/Surfactant/Water Interface: Effect of Nanoparticles Adsorbed beneath the Interface

et al. 2019

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The compression isotherm of a Langmuir film can provide information on the structural order and density of interfacial molecules. When nanoparticles are introduced to the Langmuir film at an air/liquid interface, the compression isotherm is altered substantially. In this study, we report experimental evidence of topographic corrugation of the air/surfactant/water interface due to compression of nanoparticles adsorbed underneath the surfactant layer. A monolayer of cationic surfactants is suspended in a Langmuir trough with negatively charged nanoparticles in the aqueous subsurface. Changes in structural orders of the interfacial molecules and nanoparticles were characterized using in situ sum-frequency generation (SFG) spectroscopy during compression and associated with the modified compression isotherm in the presence of nanoparticles. This work elucidated changes in the compression isotherm due to the variation of surface geometry, which is required to produce a desired Langmuir film made of nanoparticles.

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Section: Resultsmentioning

confidence: 99%

Compression-Induced Topographic Corrugation of Air/Surfactant/Water Interface: Effect of Nanoparticles Adsorbed beneath the Interface

et al. 2019

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Anisotropic Optical and Frictional Properties of Langmuir–Blodgett Film Consisting of Uniaxially‐Aligned Rod‐Shaped Cellulose Nanocrystals

Chae

Ngo

Chen

et al. 2020

Adv Materials Inter

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Langmuir-Blodgett (LB) film deposition gives an opportunity to control the packing density and orientation of anisotropic nanoparticles at a monolayer level, allowing accurate characterization of their anisotropic material properties. The uniaxial deposition of rod-shaped cellulose nanocrystals (CNCs) over a macroscopically large area is achieved by aligning the long axis of CNCs on the LB trough with the direction of the maximum drag force within the meniscus during the vertical pulling of the substrate from the LB trough. On the uniaxially-aligned LB films, anisotropic linear and non-linear optical properties of CNCs are obtained using Mueller matrix spectroscopy and sum frequency generation spectroscopy, respectively, and explained with time-dependent density functional theory calculations. Also, the frictional anisotropy of the LB film is measured using atomic force microscopy and explained theoretically. The findings of this study will be valuable for preparation of anisotropic nanoparticle thin films with uniform arrangements and utilization of their anisotropic material properties.

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Fully First-Principles Surface Spectroscopy with Machine Learning

Litman,

Lan,

Nagata

et al. 2023

J. Phys. Chem. Lett.

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Our current understanding of the structure and dynamics of aqueous interfaces at the molecular level has grown substantially due to the continuous development of surface-specific spectroscopies, such as vibrational sum-frequency generation (VSFG). As in other vibrational spectroscopies, we must turn to atomistic simulations to extract all of the information encoded in the VSFG spectra. The high computational cost associated with existing methods means that they have limitations in representing systems with complex electronic structure or in achieving statistical convergence. In this work, we combine high-dimensional neural network interatomic potentials and symmetry-adapted Gaussian process regression to overcome these constraints. We show that it is possible to model VSFG signals with fully ab initio accuracy using machine learning and illustrate the versatility of our approach on the water/air interface. Our strategy allows us to identify the main sources of theoretical inaccuracy and establish a clear pathway toward the modeling of surface-sensitive spectroscopy of complex interfaces.

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Quadrupole Contributions from Interface and Bulk

Cited by 4 publications

References 20 publications

Compression-Induced Topographic Corrugation of Air/Surfactant/Water Interface: Effect of Nanoparticles Adsorbed beneath the Interface

Compression-Induced Topographic Corrugation of Air/Surfactant/Water Interface: Effect of Nanoparticles Adsorbed beneath the Interface

Anisotropic Optical and Frictional Properties of Langmuir–Blodgett Film Consisting of Uniaxially‐Aligned Rod‐Shaped Cellulose Nanocrystals

Fully First-Principles Surface Spectroscopy with Machine Learning

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