Article
Materials Science, Multidisciplinary
Q. Z. Li, P. Elliott, J. K. Dewhurst, S. Sharma, S. Shallcross
Summary: This paper demonstrates an excellent method for describing momentum-resolved charge excitation in monolayer graphene using transient electron momentum density, with results showing excellent agreement with conduction band occupancy obtained from advanced theoretical calculations. It confirms that simple model-based tight-binding approaches can provide an excellent description for laser-induced electron dynamics in graphene, even under intense laser pulses.
Article
Chemistry, Physical
Micheline B. Soley, Pablo E. Videla, Erik T. J. Nibbering, Victor S. Batista
Summary: PCET is the underlying mechanism for important reactions in photosynthesis and hydrogen fuel cells. Proton and electron charge distribution motions can vary and occur on ultrafast time scales. Femtosecond soft-X-ray spectroscopy provides key insights into the PCET mechanism of photoinduced intramolecular tautomerization reactions.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Ya-Juan Feng, Chao Wang
Summary: The identification of molecular cluster structures has always been a fundamental and challenging issue. This study proposed an accurate and reliable approach for cluster structure identification by combining global low-lying structure search and vibrational predissociation spectral simulation. Experimental data can be used to validate the theoretical results, and the qualitative agreement between simulated and measured vibrational spectra provides solid experimental evidence for the assignment of cluster structures.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Myles C. Silfies, Arshad Mehmood, Grzegorz Kowzan, Edward G. Hohenstein, Benjamin G. Levine, Thomas K. Allison
Summary: In this study, transient absorption measurements and simulations were conducted on Salicylideneaniline (SA) under different conditions using cavity-enhanced transient absorption spectroscopy (CE-TAS). The results showed prompt excited-state intramolecular proton transfer (ESIPT) and the generation of a photochrome state in parallel with the fluorescent keto state. Increasing the internal energy led to an increase in the photochrome yield and a decrease in fluorescent yield and lifetime. In Ar clusters, the internal conversion of SA was hindered, but the photochrome yield remained unchanged.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Qin Zhang, Zhongneng Zhou, Bodan Deng, Bingyao Wang, Xiu-Wen Kang, Jinquan Chen, Bei Ding, Dongping Zhong
Summary: Phototriggers are useful molecular tools that can initiate reactions in enzymes by light for photoenzymatic design and mechanistic investigations. In this study, we incorporated the non-natural amino acid 5-cyanotryptophan (W-5CN) in a polypeptide scaffold and investigated the photochemical reaction of W-5CN-W using femtosecond transient UV/Vis and mid-IR spectroscopy. Our findings suggest that the W5CN-W pair can serve as an ultrafast phototrigger, enabling reactions in non-light-sensitive enzymes to be detected using femtosecond spectroscopy.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Karl Michael Ziems, Mats Simmermacher, Stefanie Graefe, Adam Kirrander
Summary: We investigate the role of Compton ionization in ultrafast non-resonant x-ray scattering using a molecular model system, which includes the ionization continuum via an orthonormalized plane wave ansatz. Elastic and inelastic components of the scattering signal, as well as coherent-mixed scattering that arises from electron dynamics, are calculated. By virtue of a near-quantitative distinction between scattering related to electronic transitions into bound and continuum states, we demonstrate how Compton ionization contributes to the coherent-mixed component. Analogous to inelastic scattering, the contribution to the coherent-mixed signal is significant and particularly manifests at intermediate and high-momentum transfers. Strikingly, for molecules with inversion symmetry, the exclusion of bound or continuum transitions may lead to the prediction of spurious coherent-mixed signals. We conclude that qualitative and quantitative accuracies of predicted scattering signals on detectors without energy resolution require that elements of the two-electron density operator are used. This approach inherently accounts for all accessible electronic transitions, including ionization.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Yanyu Yin, Xingju Zhao, Xiaoyan Ren, Kun Liu, Jin Zhao, Lili Zhang, Shunfang Li
Summary: In this study, the interlayer carrier dynamics of black phosphorus and MoS2 heterostructure were investigated through simulations. The results showed that the electron and hole transfer time depended on the layer number of black phosphorus, with linear and exponential relationships respectively. These findings provide new insights for improving the ultrafast carrier dynamics process in two-dimensional heterostructures.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Kalyani Chordiya, Victor Despre, Balazs Nagyilles, Felix Zeller, Zsolt Diveki, Alexander Kuleff, Mousumi Upadhyay Kahaly
Summary: Through the study of overall many-electron dynamics triggered by ionizing the outer-valence orbitals of different tautomers, we observe distinctly different charge dynamics responses among the tautomers. An experimental schematics for detecting and reconstructing such charge dynamics is proposed.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Rui-Fang Xie, Jing-Bin Zhang, Yang Wu, Laicai Li, Xiang-Yang Liu, Ganglong Cui
Summary: In this study, a nonadiabatic dynamics simulation method based on linear response time dependent density functional theory and considering the excitonic effects was used to investigate the photoinduced excitation energy transfer dynamics of a double-walled carbon nanotube (CNT) model with different excitation energies. The results showed that there was energy conversion between the local excitation (LE) exciton generated by the E11 excitation of the outer CNT and the excitons generated by the E11 excitation of the inner CNT. When the excitation energy was close to the E22 state of the outer CNT, a mixed population of different excitons was generated, with the LE exciton dominating. This study not only elucidates the mechanistic details of wavelength-dependent excitation energy transfer in a double-walled CNT model, but also highlights the roles and importance of charge transfer (CT) excitons in photoinduced excitation energy transfer. It emphasizes the significance of explicitly considering excitonic effects in electronic structure calculations and nonadiabatic dynamics simulations for understanding and designing optoelectronic properties of periodically extended systems.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Vishal Kumar Jaiswal, Piotr Kabacinski, Barbara E. Nogueira de Faria, Marziogiuseppe Gentile, Ana Maria de Paula, Rocio Borrego-Varillas, Artur Nenov, Irene Conti, Giulio Cerullo, Marco Garavelli
Summary: By combining UV transient absorption spectroscopy with sub-30-fs temporal resolution and CASPT2/MM calculations, this study provides a complete description of the primary photoinduced processes in solvated tryptophan. The role of the solvent in the relaxation dynamics of tryptophan is clarified, and evidence of vibrational coherence is presented.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Biology
Amelia L. Schneider, Amanda V. Albrecht, Kenneth Huang, Markus W. Germann, Gregory M. K. Poon
Summary: Fixed-charge forcefields are accurate and efficient tools for studying nucleic acid dynamics. Expanding the residue set and deriving accurate charges are important for their continued utility. Atomic charges derived from molecular mechanics minimization yield better results than quantum mechanical models. We present a protocol for obtaining self-consistent and optimized charges for studying the dynamics of novel DNA polymers.
Article
Chemistry, Multidisciplinary
Federico Sebastiani, Chun Yu Ma, Sarah Funke, Alexander Baumer, Dominique Decka, Claudius Hoberg, Alexander Esser, Harald Forbert, Gerhard Schwaab, Dominik Marx, Martina Havenith
Summary: This study demonstrates the sensitivity of the N-C-C-O open/close mode at 315 cm(-1) as a label-free probe for the local protonation of the amide group using precise terahertz measurements and molecular dynamics simulations. The approach is shown to be more general, as it can also be applied to other amino acids and allows for direct correlation of titration spectra with pK(a) values, showcasing the potential of terahertz spectroscopy for label-free probing of the charge state of natural amino acids in water.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Engineering, Chemical
Fang Xu, Yixing Wang, Cheng Lian, Zhi Xu
Summary: This study investigates the proton-selective transport behaviors through four types of COFs in the aqueous phase and reveals that COFs with large pores and nucleophilic sites can provide high proton conductivity and selectivity. The mechanisms of proton transport are also revealed, which can help in designing the next-generation PEMs with exceptional permselectivity.
JOURNAL OF MEMBRANE SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Takuro Tsutsumi, Yuriko Ono, Tetsuya Taketsugu
Summary: The quantum chemical approach investigates chemical reaction mechanisms based on potential energy surfaces. Automated reaction path search methods and on-the-fly molecular dynamics method provide insights into the dynamics effects on reaction mechanisms.
CHEMICAL COMMUNICATIONS
(2021)
Article
Physics, Applied
J. K. Dewhurst, S. Shallcross, I. Radu, P. Elliott, C. v. Korff Schmising, S. Sharma
Summary: By using ultrashort laser pulses, the spin dynamics of Gd-x(FeCo)(1-x) at femtosecond time scales were explored ab initio. The study found that there is a creation of an ultrafast ferromagnetic transient with different demagnetization rates for Fe and Gd, along with the rotation of Gd moments.
APPLIED PHYSICS LETTERS
(2022)
Article
Polymer Science
Sabita Kadel, Francesco Deboli, Veronique Perreault, Mateusz L. Donten, Laurent Bazinet
Summary: This study focuses on fabricating cation-coated filtration membranes with crosslinked polyethyleneimine on porous substrates as a cost-effective alternative to commercial anion-exchange membranes. Despite lower ionic conductance compared to AMX, the membranes exhibit similar electrochemical behavior. CCFMs show potential for industrial application in electrodialysis demineralization processes.
JOURNAL OF POLYMER SCIENCE
(2022)
Article
Biochemistry & Molecular Biology
Philipp J. Heckmeier, Jeannette Ruf, David Buhrke, Brankica G. Jankovic, Peter Hamm
Summary: The protein MCL-1 is essential in regulating apoptosis in various cancers by binding to BIM according to an induced fit mechanism, leading to a cascade of structural rearrangements across a wide range of time scales.
JOURNAL OF MOLECULAR BIOLOGY
(2022)
Review
Chemistry, Multidisciplinary
Olga Bozovic, Brankica Jankovic, Peter Hamm
Summary: Controlling protein activity with azobenzene photoswitches is a powerful tool to manipulate biological function, allowing changes in binding affinities, control of allostery, and initiation of out-of-equilibrium processes. By combining the potency of azobenzene photoswitching with transient spectroscopic techniques, researchers can reveal the order of events and experimentally observe biomolecular interactions in real time, providing insights into the dynamic nature of proteins.
NATURE REVIEWS CHEMISTRY
(2022)
Article
Chemistry, Physical
Seyyed Jabbar Mousavi, Arian Berger, Peter Hamm, Andrey Shalit
Summary: In this study, two-dimensional Raman-THz spectroscopy was used to investigate the crystalline structure of bromoform. The results showed that the cross peaks in the crystalline sample were sharper and could be assigned to specific vibrational modes. The frequency positions of these cross peaks corresponded to the intramolecular bending modes in the Raman dimension and the lattice modes in the THz dimension. This work expands the applicability of this spectroscopic technique to solid samples and provides new experimental evidence for the coupling between intra- and intermolecular vibrational modes.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Engineering, Chemical
Francesco Deboli, Bart Van der Bruggen, Mateusz L. Donten
Summary: This work presents a versatile chemistry platform for the fabrication of hierarchical cation and anion exchange membranes (hCEMs and hAEMs) with tuneable transport properties. The hierarchical ion exchange membranes were made by coating and UV crosslinking an acrylic ionomer on top of a PVC-SiO2 porous substrate. The properties and performance of the membranes were found to be dependent on the coating crosslinking density, with higher crosslinking density resulting in better selectivity and performance.
Article
Chemistry, Multidisciplinary
Kai Toepfer, Andrea Pasti, Anuradha Das, Seyedeh Maryam Salehi, Luis Itza Vazquez-Salazar, David Rohrbach, Thomas Feurer, Peter Hamm, Markus Meuwly
Summary: This study investigates the spectroscopy and structural dynamics of a deep eutectic mixture with varying water content using 2D IR and THz spectroscopy. Molecular dynamics simulations accurately describe the dependence of spectroscopic signatures on water content. The results demonstrate that the combination of structure-sensitive spectroscopies and molecular dynamics simulations provides molecular-level insights into the heterogeneity of such mixtures.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
David Buhrke, Norbert Michael, Peter Hamm
Summary: Phytochromes are commonly found photoreceptor proteins that undergo secondary structure refolding in response to chromophoric group photoisomerization. Two-dimensional infrared absorption spectroscopy is used to study the photoreaction of bacterial phytochrome Agp1, showing that dipole coupling between the chromophore and the tongue region plays a role in stabilizing the protein in the light-activated state.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Physical
Beliz Sertcan, Seyyed Jabbar Mousavi, Marcella Iannuzzi, Peter Hamm
Summary: Theoretical calculations of low-frequency anharmonic couplings in the beta-phase of crystalline bromoform were conducted based on density functional theory quantum chemistry calculations. The dominant role of electrical anharmonicity in the 2D Raman-THz response of both crystalline and liquid bromoform was revealed. The difference in relative cross-peak intensities between intramolecular and intermolecular modes in bromoform can be explained by the C-3v symmetry of bromoform along with orientational averaging.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Philipp J. J. Heckmeier, Jeannette Ruf, Brankica G. G. Jankovic, Peter Hamm
Summary: The study investigates the interaction between the allosteric protein MCL-1 and its natural inhibitors PUMA, BIM, and NOXA. Photoswitchable versions of MCL-1/PUMA and MCL-1/NOXA were designed, and the protein response was studied using transient infrared spectroscopy. Partial alpha-helical unfolding was observed in all cases, with varying timescales, suggesting a BH3-only-specific structural resilience in MCL-1's binding pocket.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Multidisciplinary Sciences
Brankica Jankovic, Olga Bozovic, Peter Hamm
NATURE COMMUNICATIONS
(2023)
Review
Chemistry, Multidisciplinary
Paul M. Donaldson, Greg M. Greetham, Chris T. Middleton, Bradley M. Luther, Martin T. Zanni, Peter Hamm, Amber T. Krummel
Summary: Ultrafast spectroscopy and imaging have become essential tools for scientists in various fields. The commercialization of advanced spectrometers, such as transient absorption spectrometers and vibrational sum frequency generation spectrometers, has made these measurements available to non-experts in ultrafast spectroscopy. The shift to new Yb-based lasers offers exciting new possibilities in the chemical and physical sciences, with higher efficiency and improved noise characteristics.
ACCOUNTS OF CHEMICAL RESEARCH
(2023)
Article
Chemistry, Physical
Jan Helbing, Peter Hamm
Summary: This article introduces several ways to electronically synchronize different types of amplified femtosecond laser systems using a single freely programmable electronics hardware. These methods allow for rapid probing of a wide range of timescales in a single transient absorption experiment without the need to move any delay stage. The approach is versatile and can synchronize different lasers, such as a Ti:Sa amplifier and a 100 kHz Yb-laser system. The time-resolution in the transient experiment ranges from 1 to 3 ps, depending on the method.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Multidisciplinary
David Buhrke, Yigal Lahav, Aditya Rao, Jeannette Ruf, Igor Schapiro, Peter Hamm
Summary: In this study, the researchers explored a cyanobacteriochrome called Slr1393-g3, which can switch between red-absorbing and green-absorbing forms. They used advanced IR spectroscopic methods to track the intermediates during the photocycle and discovered a new intermediate with distinct spectroscopic features. Additionally, they measured the vibrational couplings and structural disorder in these intermediate states using stationary and transient 2D IR experiments. Anharmonic QM/MM calculations were also performed to predict the spectra and suggest structural changes of the intermediates.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Seyedeh Maryam Salehi, Silvan Kaeser, Kai Toepfer, Polydefkis Diamantis, Rolf Pfister, Peter Hamm, Ursula Rothlisberger, Markus Meuwly
Summary: In this work, the structural dynamics and infrared spectroscopy of para-fluorophenol and phenol in the gas phase and in water were investigated using a combination of experiment and molecular dynamics simulations. The study found that the CF group of para-fluorophenol is highly hydrophobic, which is particularly relevant for applications in pharmaceutical chemistry.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Kerstin T. Oppelt, Laurent Severy, Mirjam Utters, S. David Tilley, Peter Hamm
Summary: This study investigated the solid-liquid interface of a rhenium-tricarbonyl complex embedded in a zirconium oxide layer deposited by atomic layer deposition (ALD) using time-resolved and steady state infrared spectroscopy. The research revealed correlations between the thickness of the ALD layer and the spectroscopic response of the system. A transition from flexible to rigid molecular environment, as well as limitations to ligand exchange and excited state quenching on the embedded complexes, were observed when the ALD layer matched the height of the molecules.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)