Impact of Electric Field on the Structural Dynamics of Water and Adsorbed Molecules near an Electrode Surface: Simulations of 2D IR Experiments.

Heterogeneous catalysis involves the chemical transformation of molecules at an electrode surface, but experimentally probing the impact of the electric field on the structural dynamics of the molecules and any accompanying solvent dynamics remains a significant challenge. In this study, we conducted molecular dynamics simulations of a system comprising pure water in contact with gold (Au) electrodes coated with 4-mercaptobenzonitrile (4-MBN) molecules, as recently measured using 2D IR spectroscopy (Ryan, M. J.

Developmental toxicity of microplastics in human stem cells using adverse outcome pathway based integrated approaches to testing and assessment approach.

Micro/nanoplastics (MNPs), detected in human tissues including the placenta, raise significant concerns regarding their potential impact on early human development. However, the mechanisms underlying their developmental toxicity remain poorly understood. To address this, we applied an Integrated Approaches to Testing and Assessment (IATA) framework to evaluate the developmental toxicity of polystyrene (PS) MNPs by combining adverse outcome pathway (AOP) development, experimental testing within an Integrated Testing Strategy (ITS), and literature-based data integration.

Enhanced Charge Transport through Ion Networks in Highly Concentrated LiSCN-Polyethylene Carbonate Solid Polymer Electrolytes.

Challenging the preference for bulky anions due to low binding energy with Li ion, the lithium thiocyanate-polyethylene carbonate (LiSCN-PEC) solid polymer electrolyte (SPE) demonstrates higher ionic conductivities (3.16 × 10 S cm) at polymer-in-salt concentration (100 mol%) compared to those with lithium bis(fluorosulfonyl)imide (LiFSI, 1.01 × 10 S cm) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, 1.

Time-resolved nonlinear microspectroscopy with Gaussian beams: Photon echo and spatially encoded coherence.

We extend our theoretical framework for time-resolved nonlinear microspectroscopy [M. Cho, J. Chem.

Mid-infrared asynchronous and interferometric transient absorption: Coherent averaging with sustained ergodicity for observing ultrafast dynamics in heterogeneous samples.

Asynchronous and interferometric transient absorption (AI-TA) spectroscopy is a powerful technique for probing ultrafast dynamics, offering both time-resolved insights and frequency-domain information with a single-point detector. In this study, we successfully measured the transient absorption signal of rod-shaped tellurium microcrystals under low pump fluence using a mid-infrared (MIR) AI-TA setup. By leveraging exceptionally stable frequency combs for both the pump and probe beams, coherent averaging in the MIR AI-TA enabled the clear observation of transient absorption signals, even in heterogeneous samples under low pump fluence.

In situ and real-time ultrafast spectroscopy of photoinduced reactions in perovskite nanomaterials.

By employing two synchronized mode-locked femtosecond lasers and interferometric detection of the pump-probe spectra-referred to as asynchronous and interferometric transient absorption-we have developed a method for broad dynamic range and rapid data acquisition. Using asynchronous and interferometric transient absorption, we examined photochemical changes during femtosecond pump-probe experiments on all-inorganic cesium lead halide nanomaterials. The laser pulse train facilitates photoreactions while allowing real-time observation of charge carrier dynamics.

Time-resolved nonlinear microspectroscopy with Gaussian beams.

Time-resolved nonlinear microspectroscopy bridges high-resolution imaging and ultrafast spectroscopy, enabling the investigation of spatially localized molecular excited state and exciton dynamics on ultrafast timescales. By integrating ultrafast techniques such as pump-probe and coherent multidimensional spectroscopy with microscopy techniques utilizing high numerical aperture objective lenses and structured beams, these approaches provide label-free chemical contrast and reveal transient phenomena critical to understanding complex systems. Recent advancements, including adaptive optics and tailored beam profiles, have further enhanced spatial and temporal control, unlocking new possibilities for studying heterogeneous systems.

Nonlinear optical detection of the orbital angular momentum of light.

Optical beams carrying orbital angular momentum (OAM) have gained significant interest due to their unique properties, enhancing various communication systems and enabling applications such as the characterization of material or molecular chirality. Generating and detecting the OAM of light is thus crucial for numerous applications but poses challenges. This paper proposes a method utilizing stimulated Raman scattering to detect the magnitude of OAM.

Asynchronous and Interferometric Nonlinear Spectroscopy (AI-NS): Expanding Temporal and Spectral Horizons.

Since the advent of time-resolved spectroscopy based on precision frequency technology of laser sources, it has been considered an alternative way to study dynamic processes in photochemical systems. This Perspective introduces asynchronous and interferometric nonlinear spectroscopy (AI-NS), a spectroscopic technique that combines asynchronously generated laser pulses and interferometric detection, offering an unprecedented temporal dynamic range with high spectral resolution and rapid data acquisition capabilities. By eliminating the need for mechanical delay stages, AI-NS facilitates the rapid collection of time-resolved data on dynamics ranging from femtoseconds to nanoseconds while simultaneously distinguishing frequency-dependent responses.

Ion Networks in Water-based Li-ion Battery Electrolytes.

ConspectusWater-in-salt electrolytes (WiSEs) are promising electrolytes for next-generation lithium-ion batteries (LIBs), offering critical advantages like nonflammability and improved safety. These electrolytes have extremely high salt concentrations and exhibit unique solvation structures and transport mechanisms dominated by the formation of ion networks and aggregates. These ion networks are central to the performance of WiSEs, govern the transport properties and stability of the electrolyte, deviating from conventional dilute aqueous or organic electrolytes.

Recasting the wobbling-in-a-cone model for the rotational anisotropy of phenylselenocyanate in poly(methyl methacrylate): Effect of internal bond rotation and polymer segmental motion.

The rotational anisotropy of a molecule in a constrained environment is modeled by wobbling-in-a-cone (WIAC) motion, which describes the angular space sampled by the molecule. Recent polarization-selective IR pump-probe measurements have applied this model to phenylselenocyanate in amorphous polymers, aiming to probe the surrounding free volume. A faster rotational timescale was hypothesized to reflect the angular space within the static voids of the polymer matrix, while a slower timescale relates to constraint release by the polymer backbones.

Quantitative Analysis of the Li-Ion Solvation Structure in Li-Ion Battery Electrolytes Using ATR-FTIR Spectroscopy.

Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy is widely used to study condensed materials due to its convenient sample preparation and ability to avoid absorption saturation. Recently, it has been applied to and observations of chemical reactions within electrochemical devices, such as lithium-ion batteries. However, because ATR-FTIR spectroscopy relies on frequency-dependent attenuated reflectance, quantitative concentration measurements of chemical species using the Beer-Lambert law are challenging.

Ultrafast measurement of photoacoustic parameters with mid-infrared frequency comb transients.

The photoacoustic (PA) effect has been widely used in various applications, including highly sensitive spectroscopy and label-free, non-invasive imaging. In this work, we demonstrate a fast and precise measurement of PA parameters for light-absorbing liquids using mid-infrared asynchronous sampling pump-probe measurements. To simulate the observed PA oscillation signals and extract various PA parameters as a function of pump power, we derived analytical solutions of the PA wave equation driven by a train of ultrashort Gaussian pump pulses.

Molecular Photothermal Effect on the 2D-IR Spectroscopy of Acetonitrile-Based Li-Ion Battery Electrolytes.

Advancements in Li-ion battery (LIB) technology hinge on an understanding of Li-ion solvation and charge transport dynamics. Ultrafast two-dimensional infrared (2D-IR) spectroscopy has been used to investigate these dynamics in electrolytes by probing chemical exchange processes through time-dependent cross-peak analysis. However, accurate interpretation is complicated by factors such as vibrational energy transfer and molecular photothermal effect (MPTE), affecting cross-peak evolution.

Solvation Structures and Transport Mechanisms of Cations in Water-in-Bisalt Electrolytes for High-Concentration Lithium-Ion Batteries Revealed by Molecular Dynamics Simulations.

The development of safe and cost-effective electrolytes for rechargeable batteries is currently underway. While water-based electrolytes hold promise, their restricted electrochemical stability window poses a challenge. Combining multiple ionic species emerges as a promising strategy to broaden this stability window and optimize Li-ion battery performance.

Label-Free Interference Imaging of Intracellular Trafficking.

Intracellular cargo trafficking is a highly regulated process responsible for transporting vital cellular components to their designated destinations. This intricate journey has been a central focus of cellular biology for many years. Early investigations leaned heavily on biochemical and genetic approaches, offering valuable insight into molecular mechanisms of cellular trafficking.

Dual phase-detected infrared photothermal microscopy.

Infrared photothermal microscopy (IPM) has recently gained considerable attention as a versatile analytical platform capable of providing spatially resolved molecular insights across diverse research fields. This technique has led to numerous breakthroughs in the study of compositional variations in functional materials and cellular dynamics in living cells. However, its application to investigate multiple components of temporally dynamic systems, such as living cells and operational devices, has been hampered by the limited information content of the IP signal, which only covers a narrow spectral window (< 1 cm).

Water-Ion Interaction Determines the Mobility of Ions in Highly Concentrated Aqueous Electrolytes.

Solvation engineering plays a critical role in tailoring the performance of batteries, particularly through the use of highly concentrated electrolytes, which offer heterogeneous solvation structures of mobile ions with distinct electrochemical properties. In this study, we employed spectroscopic techniques and molecular dynamics simulations to investigate mixed-cation (Li/K) acetate aqueous electrolytes. Our research unravels the pivotal role of water in facilitating ion transport within a highly viscous medium.

Efficient and Inexpensive Synthesis of N-Labeled 2-Azido-1,3-dimethylimidazolinium Salts Using NaNO Instead of NaNNN.

N-Labeled azides are important probes for infrared and magnetic resonance spectroscopy and imaging. They can be synthesized by reaction of primary amines with a N-labeled diazo-transfer reagent. We present the synthesis of N-labeled 2-azido-1,3-dimethylimidazolinium salts as a N-labeled diazo-transfer reagent.

Molecular dynamics simulation study of water structure and dynamics on the gold electrode surface with adsorbed 4-mercaptobenzonitrile.

Understanding water dynamics at charged interfaces is of great importance in various fields, such as catalysis, biomedical processes, and solar cell materials. In this study, we implemented molecular dynamics simulations of a system of pure water interfaced with Au electrodes, on one side of which 4-mercaptobenzonitrile (4-MBN) molecules are adsorbed. We calculated time correlation functions of various dynamic quantities, such as the hydrogen bond status of the N atom of the adsorbed 4-MBN molecules, the rotational motion of the water OH bond, hydrogen bonds between 4-MBN and water, and hydrogen bonds between water molecules in the interface region.

Dielectric Response and Linear Absorption Spectroscopy of Ionic Systems.

Time-dependent electric fields applied to ionic systems can induce both a dielectric and a conductive response, leading to the generation of macroscopic polarization and current, respectively. It has long been recognized that it is not possible to determine the two types of responses separately. However, this aspect is often not adequately accounted for in dielectric and absorption spectroscopies of ionic systems.