A5001165782- Spectroscopy and Quantum Chemical Studies
- Conducting polymers and applications
- Advanced Battery Materials and Technologies
- Molecular spectroscopy and chirality
- Organic Electronics and Photovoltaics
- Advancements in Battery Materials
- Perovskite Materials and Applications
- Spectroscopy and Laser Applications
- Advanced Battery Technologies Research
- Protein Structure and Dynamics
- Spectroscopy Techniques in Biomedical and Chemical Research
- TiO2 Photocatalysis and Solar Cells
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- Photoreceptor and optogenetics research
- Electrochemical Analysis and Applications
- Organic Light-Emitting Diodes Research
- Ionic liquids properties and applications
- Supercapacitor Materials and Fabrication
- Thermodynamic properties of mixtures
- Hemoglobin structure and function
- Quantum Dots Synthesis And Properties
- Advanced Photocatalysis Techniques
- Terahertz technology and applications
- Advanced Chemical Sensor Technologies
Korea University
2016-2025
Institute for Basic Science
2016-2025
Government of the Republic of Korea
2016-2019
Chung-Ang University
2012-2016
University of California, Berkeley
2011
Stanford University
2004-2010
University of Rochester
2008
Osaka University
2008
Sookmyung Women's University
2004
In general, the formation and dissociation of solute-solvent complexes have been too rapid to measure without disturbing thermal equilibrium. We were able do so with use two-dimensional infrared vibrational echo spectroscopy, an ultrafast analog nuclear magnetic resonance spectroscopy. The equilibrium dynamics phenol complexation benzene in a benzene-carbon tetrachloride solvent mixture measured real time by appearance off-diagonal peaks spectrum hydroxyl stretch. constant tau(d) for...
Ultrafast two-dimensional infrared (2D-IR) vibrational echo spectroscopy can probe structural dynamics under thermal equilibrium conditions on time scales ranging from femtoseconds to ∼100ps and longer. One of the important uses 2D-IR is monitor dynamical evolution a molecular system by reporting dependent frequency fluctuations an ensemble probes. The frequency-frequency correlation function (FFCF) connection between experimental observables microscopic thus central object interest in...
Vibrational echo correlation spectroscopy experiments on the OD stretch of dilute HOD in H(2)O are used to probe structural dynamics water. A method is demonstrated for combining spectra taken with different infrared pulse bandwidths (pulse durations), making it possible use data collected from many which laser properties not identical. Accurate measurements anharmonicity (162 cm(-1)) presented and analysis. In addition, recent accurate determination vibrational lifetime (1.45 ps) time scale...
Lithium-ion batteries (LIBs) have been deployed in a wide range of energy-storage applications and helped to revolutionize technological development. Recently, lithium ion battery that uses superconcentrated salt water as its electrolyte has developed. However, the role facilitating fast transport such highly concentrated solutions is not fully understood yet. Here, femtosecond IR spectroscopy molecular dynamics simulations are used show bulk-like coexists with interfacial on aggregates. We...
Ultrafast two-dimensional infrared (2D-IR) vibrational echo spectroscopy can probe the fast structural evolution of molecular systems under thermal equilibrium conditions. Structural dynamics are tracked by observing time 2D-IR spectrum, which is caused frequency fluctuations mode(s) excited during experiment. However, there a variety effects that produce line shape distortions and prevent correct determination frequency-frequency correlation function (FFCF), describes connects experimental...
Ultrafast two dimensional infrared (2D-IR) vibrational echo spectroscopy has emerged as a powerful method for the study of molecular dynamics under thermal equilibrium conditions occurring on ultrafast time scales. Here, we describe experimental details 2D-IR including setup, pulse sequence, heterodyne detection, and extraction mainly absorptive part spectrum. As an example, measurements hydrogen bond neat water in high concentration NaBr solution are presented compared. The experiments...
Generally, rotational isomerization about the carbon-carbon single bond in simple ethane derivatives room-temperature solution under thermal equilibrium conditions has been too fast to measure. We achieved this goal using two-dimensional infrared vibrational echo spectroscopy observe between gauche and trans conformations of an derivative, 1-fluoro-2-isocyanato-ethane (1), a CCl4 at room temperature. The time constant is 43 picoseconds (ps, 10(-12) s). Based on value density functional...
The experimental technique and applications of ultrafast two-dimensional infrared (2D IR) vibrational echo spectroscopy are presented. Using ultrashort pulses optical heterodyne detection to provide phase information, unique information can be obtained about the dynamics, interactions, structures molecular systems. form time evolution 2D IR spectrum permits examination processes that cannot studied with linear absorption experiments. Three examples given: organic solute-solvent complex...
High-mobility and low-voltage-operated organic field-effect transistors (OFETs) are demonstrated by the design of a new fluorinated benzothiadiazole-based conjugated polymer with high-k dielectrics. A record-breaking high hole mobility 9.0 cm2 V−1 s−1 for semiconducting polymers is achieved excellent planarity polymer. As service to our authors readers, this journal provides supporting information supplied authors. Such materials peer reviewed may be re-organized online delivery, but not...
Abstract Lithium cation is the charge carrier in lithium-ion battery. Electrolyte solution battery usually based on mixed solvents consisting of polar carbonates with different aliphatic chains. Despite various experimental evidences indicating that lithium ion forms a rigid and stable solvation sheath through electrostatic interactions carbonates, both structure more importantly fluctuation dynamics functional role carbonate solvent molecules have not been fully elucidated yet femtosecond...
Two donor-π-spacer-acceptor (D-π-A) organic dyes were designed as photochromic with the same π-spacer and acceptor but different donors, based on their electron-donating strength. Various structural, electronic, optical properties, chemical reactivity parameters, certain crucial factors that affect short-circuit current density (Jsc) open circuit voltage (Voc) investigated computationally using functional theory time-dependent theory. The trans-cis isomerization of these azobenzene-based its...
Electroluminescence from quantum dots (QDs) is a suitable photon source for futuristic displays offering hyper-realistic images with free-form factors. Accordingly, nondestructive and scalable process capable of rendering multicolored QD patterns on scale several micrometers needs to be established. Here, direct photopatterning heavy-metal-free QDs reported using branched light-driven ligand crosslinkers (LiXers) containing multiple azide units. The LiXers effectively interlock films via...
Folded proteins can exist in multiple conformational substates. Each substate reflects a local minimum on the free-energy landscape with distinct structure. By using ultrafast 2D-IR vibrational echo chemical-exchange spectroscopy, switching between two well defined substates of myoglobin mutant is observed ≈50-ps time scale. The dynamics are directly measured through growth cross peaks spectra CO bound to heme active site. involves motion distal histidine/E helix that changes location...
Ultrafast two-dimensional (2D) infrared vibrational echo experiments and theory are used to examine chemical exchange between solute-solvent complexes the free solute for phenol three solvent complex partners, p-xylene, benzene, bromobenzene, in mixed solvents of partner CCl4. The measure time evolution 2D spectra hydroxyl (OD) stretching mode phenol. time-dependent analyzed using diagrammatic perturbation with a model that includes (formation dissociation complexes), spectral diffusion both...
The performance of planar perovskite solar cells was enhanced by using hole transporting materials containing triphenylamine groups with a multi-armed structure.
The marked difference in the ionic conductivities of linear carbonate (LC) electrolyte solutions despite their similar viscosities and permittivities is a long-standing puzzle. This study unraveled critical impact solvent conformational isomerism on salt dissociation 0.1–3.0 M LiPF6 dimethyl (DMC), ethyl methyl (EMC), diethyl (DEC) using Raman dielectric relaxation spectroscopies. extent LC solutions, which decreased order DMC > EMC DEC, closely related to fraction polar cis–trans...
Abstract Lithium metal batteries (LMBs) have the potential to deliver a greater specific capacity than any commercially used lithium battery. However, excessive dendrite growth and low Coulombic efficiencies (CEs) are major hurdles preventing commercialization of LMBs. In this study, two different salts, difluorophosphate (LiDFP) bis(trifluoromethanesulfonyl)imide (LiTFSI), chosen for use in concentrated electrolytic systems. By mixing salts with vastly cation–anion interaction energies, ion...
Solvation engineering plays a critical role in tailoring the performance of batteries, particularly through use highly concentrated electrolytes, which offer heterogeneous solvation structures 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 pivotal water facilitating ion transport within viscous medium. Notably,...
Ultrafast 2D IR vibrational echo spectroscopy is described and a number of experimental examples are given. Details the method including pulse sequence, heterodyne detection, determination absorptive component spectrum outlined. As an initial example, stretching mode CO bound to protein myoglobin (MbCO) presented. The time dependence MbCO, which caused by structural evolution, presented its relationship frequency–frequency correlation function used make assignments based on comparisons...
Carbonate electrolytes in lithium-ion batteries play a crucial role conducting lithium ions between two electrodes. Mixed solvent consisting of linear and cyclic carbonates are commonly used commercial batteries. To understand how the introduce different solvation structures dynamics, we performed molecular dynamics simulations representative electrolyte systems containing either or carbonate solvents. We then modeled their two-dimensional infrared (2DIR) spectra carbonyl stretching mode...