Article
Chemistry, Multidisciplinary
Stefan Mueller, Julian Luettig, Luisa Brenneis, Dan Oron, Tobias Brixner
Summary: This study investigates the correlations between excitons in semiconductor quantum dots using multiple-quantum two-dimensional fluorescence spectroscopy, providing insights into the properties of biexcitons and triexcitons. The method employed allows for a comprehensive understanding of multiexcitonic species in quantum dots and other semiconductor nanostructures.
Article
Chemistry, Physical
Xuan Leng, Yaming Yan, Ruidan Zhu, Jiading Zou, Wenzhao Zhang, Qiang Shi
Summary: Two-dimensional electronic spectroscopy (2DES) is commonly used to study intermolecular electronic and vibronic coherence in light-harvesting complexes. However, intramolecular vibrational coherence can also contribute to the spectra, making it difficult to distinguish the different coherences. This study explores the possibility of selectively screening vibrational coherence using polarization-dependent 2DES, and demonstrates that population and vibrational coherence signals can be largely suppressed, allowing for clearer observation of intermolecular coherence.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Lars Mewes, Rebecca A. Ingle, Andre Al Haddad, Majed Chergui
Summary: Two-dimensional Fourier transform spectroscopy is a promising technique for studying ultrafast molecular dynamics, providing a more complete picture of dynamics with broadband laser pulses. This experiment presented visible broadband 2D spectra of dye molecules, revealing vibrational coherences and information about structural motion, and allowing for acquisition of 2D spectra with high bandwidth and temporal resolution.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Kelsey A. Parker, Jonathan D. Schultz, Niven Singh, Michael R. Wasielewski, David N. Beratan
Summary: This study investigates the ability of simple feedforward neural networks (NNs) to map simulated 2D electronic spectra to underlying physical Hamiltonians. The results demonstrate that NNs can accurately characterize most Hamiltonian parameters, aiding in interpreting 2D spectra.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Qizhou Chen, Yan Ho Kwok, Weijun Zhou, Guanhua Chen, Shaul Mukamel
Summary: A new time-domain simulation protocol for two-dimensional electronic spectra with photocurrent detection is presented in this study. Time-dependent density functional theory is applied to evaluate the photocurrent response, and a non-perturbative phase-matching approach is implemented to extract the fourth-order photocurrent signal. The simulations reveal resonant interactions between transition dipoles and incident pulses, and the identification of different sample-electrode couplings based on peaks/valleys in photocurrent spectra. Additionally, the qualitative reproduction of experimental spectra of a PbS quantum dot photocell shows stimulated electron dynamics.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
James R. Hamilton, Edoardo Amarotti, Carlo N. Dibenedetto, Marinella Striccoli, Raphael D. Levine, Elisabetta Collini, Francoise Remacle
Summary: In this study, electronic coherence signatures are directly identified in the time-frequency maps measured in 2DES, and the advantages of this approach are discussed. The fast-femtosecond beatings of electronic coherences in ensemble dimers of quantum dots (QDs) are applied and characterized at room temperature in solution. The time-frequency maps allow exploiting electronic coherences without additional post-processing and with fewer 2DES measurements.
Article
Chemistry, Physical
Kritanjan Polley, Roger F. Loring
Summary: The optimized mean trajectory (OMT) approximation is a semiclassical method for studying vibrational-electronic (2DVE) spectra in a bimolecular system, and it can approximate exact quantum dynamics well. This method has previously been applied to two-dimensional infrared and electronic spectra, and has been extended to the study of 2DVE spectra.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
James D. Gaynor, Robert B. Weakly, Munira Khalil
Summary: The development of complete orientational response functions for a model system allows for simulation of polarization-selective 2D EV and 2D VE spectra with arbitrary combinations of linearly polarized electric fields. Analytical methods are proposed to isolate desired signals within complicated spectra and extract relative orientation between vibrational and vibronic dipole moments. Time-dependent peak amplitudes of coherence peaks are discussed as a means for isolating desired signals within the time-domain.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Optics
Xuanchao Zhang, Zihui Liu, Ajay Jha, Xian-Ting Liang, Michael Thorwart, R. J. Dwayne Miller, Hong-Guang Duan
Summary: We use 2DEV spectroscopy to investigate the coherent dynamics of coupled vibrational modes. By separating excitation and detection in different frequency regimes, we can directly observe the electronic and vibrational coherences in the time-evolved 2DEV spectra. The complexity of vibrational coherence between two coupled modes is revealed by cross peaks in the 2DEV spectra. With time traces, we can track the changes in vibrational coherence in the monomer and dimer models. Our findings demonstrate the effectiveness of 2DEV spectroscopy in unraveling the complexity of coupled vibrational modes and the interaction between electronic and vibrational coherences in molecular systems.
JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Sergej Markmann, Martin Franckie, Shovon Pal, David Stark, Mattias Beck, Manfred Fiebig, Giacomo Scalari, Jerome Faist
Summary: This study investigates the nonlinear system properties of an unbiased quantum cascade structure using two-dimensional THz spectroscopy, revealing multiple nonlinear signals and subband lifetimes of 4-8 ps. Coherent population exchange among intersubband levels is observed during relaxation, confirmed by simulations. Experimental results are modeled using a time-resolved density matrix based on the Lindblad master equation, providing qualitative replication and insight into their microscopic origin.
Article
Optics
Jieli Yan, Stephen Revesz, Danfu Liang, Hebin Li
Summary: Optical two-dimensional coherent spectroscopy (2DCS) is a useful tool for studying energy level structure and dynamics in atomic ensembles. In this study, a broadband optical 2DCS experiment was conducted on rubidium atoms, which have different D line characteristics compared to potassium atoms. The experimental results were consistent with simulated spectra based on the perturbation solutions. This work allows for the study of many-body interactions and correlations in rubidium atoms using double-quantum and multiquantum 2DCS.
Article
Physics, Multidisciplinary
Ahmet Demir, Neal Staley, Samuel Aronson, Spencer Tomarken, Ken West, Kirk Baldwin, Loren Pfeiffer, Raymond Ashoori
Summary: This research utilized laterally large and low-disorder GaAs quantum-well-based quantum dots to study tunneling of single electrons, identifying single-electron capacitance peaks in the addition spectrum. Two remarkable phenomena were observed in the Landau level filling factor range of nu = 2 to nu = 5: Coulomb blockade peaks due to the entrance of two electrons instead of one, and uniform appearance of double-height peaks at and near nu = 5/2 with a magnetic field flux periodicity of h/2e.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
Jacob S. Higgins, Anna R. Dardia, Chidera J. Ndife, Lawson T. Lloyd, Elizabeth M. Bain, Gregory S. Engel
Summary: We present a method to deterministically isolate population transfer kinetics from two-dimensional electronic spectroscopic signals. By characterizing the dynamics of all possible subensembles of excited state systems and removing pathways from the spectra, we can extract signals that evolve according to energy transfer kinetics. The method is robust for complex excited state systems.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Physical
Eric A. Arsenault, Addison J. Schile, David T. Limmer, Graham R. Fleming
Summary: The study introduced a heterodimer model to investigate various mechanisms of vibronic coupling and their impact on energy transfer. Experimental findings showed that Franck-Condon activity alters excitonic structure, while Herzberg-Teller activity results in significant side-band transitions. Comparing quantum beating patterns from simulated 2DEV spectra can provide insight into the mechanism of energy transfer and determine the role of specific vibronic coupling mechanisms in such processes.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Dmitry Miserev, Jelena Klinovaja, Daniel Loss
Summary: The research focuses on the magnetic instabilities of two-valley semiconductors with spin-orbit interaction, in-plane magnetic field, and electron-electron interaction. It reveals the presence of four nontrivial magnetic phases and the existence of two tricritical points at zero temperature.
Article
Environmental Sciences
Haeju Kim, Dawoon Jang, Seungjoo Choi, Jeongho Kim, Sungjin Park
Summary: The activation with nitric acid improves the photocatalytic activity of 3D melamine-derived C3N4 materials in degrading organic pollutants. NT-MCN shows better charge transfer ability compared to MCN.
Article
Environmental Sciences
Hye Jin Kang, Dong Ii Won, Yeongsu Lim, Jeongho Kim, Wan In Lee
Summary: The study found that Pt deposition greatly enhances the photocatalytic activity of ATO/TiO2, while Au or Ag depositions have less significant effects. Spectroscopic analysis indicated that Pt is most effective in scavenging electrons from the ATO CB. Pt/ATO/TiO2 produced significantly more CO2 than other catalysts, suggesting that Pt deposition can suppress charge recombination pathways effectively.
Article
Biochemistry & Molecular Biology
Jain Gu, Seonggon Lee, Seunghwan Eom, Hosung Ki, Eun Hyuk Choi, Yunbeom Lee, Shunsuke Nozawa, Shin-ichi Adachi, Jeongho Kim, Hyotcherl Ihee
Summary: The study investigated the influence of fluorination on the reaction dynamics and solute-solvent interactions in solution-phase reactions by conducting a TRXL experiment on C2F4I2 in cyclohexane. The data revealed that the solvent dependence of C2F4I2's photoreaction is less significant than that of C2H4I2, and the nongeminate recombination leading to the formation of I-2 is slower in cyclohexane compared to methanol.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2021)
Article
Chemistry, Multidisciplinary
Hosung Ki, Seungjoo Choi, Jungmin Kim, Eun Hyuk Choi, Seonggon Lee, Yunbeom Lee, Kihwan Yoon, Chi Woo Ahn, Doo-Sik Ahn, Jae Hyuk Lee, Jaeku Park, Intae Eom, Minseok Kim, Sae Hwan Chun, Joonghan Kim, Hyotcherl Ihee, Jeongho Kim
Summary: In this study, an alternative method, femtosecond time-resolved X-ray liquidography (fs-TRXL), was used to monitor microscopic structural motions related to the Optical Kerr effect response in molecular liquids using X-ray solution scattering. Different types of molecular motions were successfully resolved selectively without the need for theoretical modeling, based on anisotropy and extra structural information in the scattering data.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Multidisciplinary Sciences
Eun Hyuk Choi, Jong Goo Kim, Jungmin Kim, Hosung Ki, Yunbeom Lee, Seonggon Lee, Kihwan Yoon, Joonghan Kim, Jeongho Kim, Hyotcherl Ihee
Summary: Roaming reaction is a reaction pathway that yields products in the long-range potential region, explaining the unimolecular dissociation and isomerization of various molecules. This study investigates the structural dynamics during a roaming-mediated isomerization process, visualizing atomic movements following frustrated bond fission.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Environmental
Seung Ho Yook, Ho Young Kim, Seok Jun Kim, Seungjoo Choi, Taehyun Kwon, Handong Cho, Jun Myung Kim, Ki Ro Yoon, Sunhee Jo, So Young Lee, Hyoung-Juhn Kim, Hae Jung Son, Keun Hwa Chae, Jeongho Kim, Kwan Young Lee, Jin Young Kim
Summary: This study investigates the effect of chemically durable mesoporous silica shell on the antioxidation efficiency of CeOx nanomaterials. It is found that the mSiO2 shell can enhance the antioxidation efficiency of CeOx by facilitating dispersion of nanoparticles and increasing the ratio of highly active Ce(III) states. Proton exchange membranes based on CeOx/mSiO2 also exhibit lower degradation rate and excellent durability in energy conversion devices.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Nanoscience & Nanotechnology
Hyunhong Kim, Seung Ho Yook, Ho Young Kim, Yonghoon Choi, Yeongsu Lim, Yujin Hwang, Jeongho Kim, Kwan Young Lee, Seung Soon Jang, Jongnam Park, Jin Young Kim
Summary: This study reports on the surface-engineered cerium oxide nanoparticles (CNPs) that enhance the antioxidant properties and durability of polymer electrolyte membrane fuel cells (PEMFCs). The researchers also found that negatively charged CNPs with sulfonic acid groups as the surface modifier showed the highest compatibility with the polymer electrolyte membrane, resulting in improved stability and performance of the fuel cell.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Chemistry, Physical
Dawoon Jang, Seungjoo Choi, Suyeon Lee, Tae-Woo Lee, Seong-Ju Hwang, Hyungjun Kim, Jeongho Kim, Sungjin Park, Nam Hee Kwon, Kyung Yeon Jang
Summary: This study presents a water-assisted method to enhance the photocatalytic activities of carbon nitride by controlling intraplanar structures associated with H bonds and amine bridges.
APPLIED CATALYSIS B-ENVIRONMENT AND ENERGY
(2022)
Article
Chemistry, Multidisciplinary
Suyeon Lee, Eun Young Shin, Dawoon Jang, Seungjoo Choi, Hyeju Park, Jeongho Kim, Sungjin Park
Summary: Degradation of organic pollutants is an important research area to solve environmental issues. Metal-free carbon nitride (C3N4) materials have a great potential as cost-effective and environment-friendly photocatalysts for this purpose. In this study, mesoporous C3N4 materials were developed through self-assembly and showed excellent photocatalytic activities for degrading rhodamine B under visible light irradiation. These materials exhibited higher surface areas, better adsorption ability of visible light, and longer lifetimes of the photoexcited electrons compared to common C3N4 samples, which contribute to their outstanding photocatalytic performance.
BULLETIN OF THE KOREAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
In Seok Yang, You Jin Park, Yujin Hwang, Hoi Chang Yang, Jeongho Kim, Wan In Lee
Summary: Li-doped CuSCN films act as hole-transporting materials in perovskite solar cells, showing improved crystallinity and hole mobility. The addition of a small amount of PCPDTBT further enhances the performance and stability of the solar cells.
Article
Chemistry, Physical
Key Young Oang, Sungjun Park, Jiwon Moon, Eunji Park, Hyun Kyung Lee, Tokushi Sato, Shunsuke Nozawa, Shin-ichi Adachi, Joonghan Kim, Jeongho Kim, Jeong-Hun Sohn, Hyotcherl Ihee
Summary: Time-resolved X-ray liquidography (TRXL) is a powerful technique for studying the structural dynamics of small molecules and macromolecules in liquid solutions. However, it has limited sensitivity for small molecules containing light atoms only, making the signal from solvent molecules dominate. This study presents an alternative approach using solvent temperature change to detect the dynamics of photoinduced reactions, allowing the identification of intermediates and reaction pathways in small molecules without heavy atoms.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Yu-Na Kim, Ju-Hee Jo, Jeongho Kim, Hui-Seon Kim, Wan In Lee
Summary: Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is commonly used as a dopant in 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluor-ene (spiro-MeOTAD), but it results in poor thermal stability. Recently, zinc(II) bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2) has been proposed as a potential replacement for LiTFSI. This study explores the use of Zn(TFSI)2 as a dopant for spiro-MeOTAD to investigate the thermal stability of perovskite solar cells (PSCs).
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Hosung Ki, Tae Wu Kim, Jiwon Moon, Jungmin Kim, Yunbeom Lee, Jun Heo, Kyung Hwan Kim, Qingyu Kong, Dmitry Khakhulin, Gemma Newby, Joonghan Kim, Jeongho Kim, Michael Wulff, Hyotcherl Ihee
Summary: The photoactivation mechanism of Os-3(CO)(12) at 400 nm was investigated using time-resolved X-ray liquidography, revealing two pathways: vibrational relaxation following internal conversion and ligand dissociation to form Os-3(CO)(11) with a ligand vacancy.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Sunhong Jun, Cheolhee Yang, Seungjoo Choi, Megumi Isaji, Hitoshi Tamiaki, Hyotcherl Ihee, Jeongho Kim
Summary: In this study, the exciton delocalization length (EDL) in chlorosomes was determined using two-dimensional electronic spectroscopy (2D-ES). The EDL was found to vary with temperature and excitation frequency, with high-frequency phonons being more activated at 298 K compared to 77 K. The research provides insights into the energy transfer processes in chlorosomes under different conditions.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Jin Woo Park, Yeongsu Lim, Kyung-Yeon Doh, Min Tai Jung, Young In Jeon, In Seok Yang, Hyeon-seo Choi, Jeongho Kim, Donghwa Lee, Wan In Lee
Summary: Cu-doped Ag2BiI5 powders were synthesized and used as light absorbers in solar cells, leading to a notable increase in power conversion efficiency. The enhancement was mainly attributed to the significant increase in light absorption caused by Cu doping. Additionally, Cu doping did not affect the stability of Ag2BiI5 under high humidity conditions.
SUSTAINABLE ENERGY & FUELS
(2021)