Reaction kinetics and dynamics

  • Article
    | Open Access

    The ponderomotive effect experienced by electrons in a molecule under a transient electric field impacts the reactivity, but has been difficult to detect. The authors observe a ponderomotive force on the excess quasi-free electron in the non-valence bound state of three molecular anions, by measuring the photodetachment spectrum under irradiation with a non-resonant wavelength.

    • Do Hyung Kang
    • , Jinwoo Kim
    •  & Sang Kyu Kim
  • Article
    | Open Access

    Polycyclic aromatic hydrocarbons play an important role in interstellar chemistry, where interaction with high energy photons can induce ionization and fragmentation reactions. Here the authors, with XUV-IR pump-probe experiments, investigate the ultrafast photoinduced dynamics of fluorene, phenanthrene and pyrene, providing insight into their preferred reaction channels.

    • J. W. L. Lee
    • , D. S. Tikhonov
    •  & M. Schnell
  • Article
    | Open Access

    Identifying a concerted or stepwise mechanism in Diels–Alder reactions is experimentally challenging. Here the authors demonstrate the coexistence of both mechanisms in the reaction of 2,3-dibromobuta-1,3-diene with propene ions, using a conformationally controlled molecular beam reacting with trapped ions and ab initio computations

    • Ardita Kilaj
    • , Jia Wang
    •  & Stefan Willitsch
  • Article
    | Open Access

    The roaming reaction is a common process in the gas phase and in solution, but observation of the involved atomic movements has been challenging. The authors, using femtosecond time-resolved X-ray liquidography, resolve the detailed structural dynamics at the onset of a roaming reaction in the photoinduced isomerization of BiI3 in solution.

    • Eun Hyuk Choi
    • , Jong Goo Kim
    •  & Hyotcherl Ihee
  • Article
    | Open Access

    Extension of nanostructure fabrication in the single-nm regime is a promising but fabrication of nanostructures with high aspect ratios remains challenging. Here, the authors use high energy charged particles to produce free-standing 1D organic nanostructures with extremely high aspect ratios and controlled number density.

    • Koshi Kamiya
    • , Kazuto Kayama
    •  & Shu Seki
  • Article
    | Open Access

    Active coacervate droplets are droplets coupled to a chemical reaction that maintains them out of equilibrium, which can be used to drive active processes, but coacervates are still subject to passive processes that compete with or mask growth. Here, the authors present a nucleotide-based model for active coacervate droplets that form and grow by fuel-driven synthesis of ATP, and, importantly, do not undergo Ostwald ripening.

    • Karina K. Nakashima
    • , Merlijn H. I. van Haren
    •  & Evan Spruijt
  • Article
    | Open Access

    Femtosecond time-resolved X-ray solution scattering (fs-TRXSS) measurements provide information on the structural dynamics of proteins in solution. Here, the authors present a structure refinement method for the analysis of fs-TRXSS data and use it to characterise the ultrafast structural changes of homodimeric haemoglobin.

    • Yunbeom Lee
    • , Jong Goo Kim
    •  & Hyotcherl Ihee
  • Article
    | Open Access

    The dynamics of water molecules at interfaces controls natural and artificial processes, but experimental investigations have been challenging. Here the authors investigate water molecules on a graphene surface using helium spin-echo spectroscopy, and reveal a regime where freely mobile molecules undergo strong repulsive mutual interactions which inhibit ice nucleation.

    • Anton Tamtögl
    • , Emanuel Bahn
    •  & William Allison
  • Article
    | Open Access

    So far, only a few chemical oscillators based on organic reactions have been developed. Here, the authors report both autocatalytic and oscillatory reaction networks that form substituted guanidines from thiouronium salts; when coupled to cascade cyclization, this reaction network produces oscillations in the production of pyrimidine-based heterocycles.

    • Alexander I. Novichkov
    • , Anton I. Hanopolskyi
    •  & Sergey N. Semenov
  • Article
    | Open Access

    Predicting the conversion and selectivity of a photochemical reactions is challenging. Here, the authors introduce a framework for the quantitative prediction of the time-dependent progress of a photoligation reaction and predict LED-light induced conversion through a wavelength-resolved numerical simulation.

    • Jan P. Menzel
    • , Benjamin B. Noble
    •  & Christopher Barner-Kowollik
  • Article
    | Open Access

    Oxidation of volatile organic compounds leads to aerosol formation in the atmosphere, but the mechanism of some fast reactions is still unclear. The authors, using quantum chemical modelling and experiments, reveal that in key monoterpenes the cyclobutyl ring that would hinder the reactivity is broken in the early exothermic steps of the reaction.

    • Siddharth Iyer
    • , Matti P. Rissanen
    •  & Theo Kurtén
  • Article
    | Open Access

    Spin polarization is at the basis of quantum information and underlies some natural processes, but many aspects still need to be explored. Here, the authors, by quantum mechanical computations, show that even a weak spin-orbit coupling near a conical intersection can induce large spin selection, with consequences for spin manipulation in photochemical or electrochemical reactions.

    • Yanze Wu
    •  & Joseph E. Subotnik
  • Article
    | Open Access

    Crystal defects critically influence surface chemical reactions in nanomaterials, yet the basic mechanisms at play are still elusive. Here, the authors show the atomic-scale dynamics of surface oxidation at coherent planar defects in Ag and Pd, revealing how twins and stacking-faults selectively oxidize metallic nanocrystals.

    • Qi Zhu
    • , Zhiliang Pan
    •  & Jiangwei Wang
  • Article
    | Open Access

    Porous materials acting as molecular sieves for propylene/propane separation are important for the petrochemical industry. Here the authors show an example of how specific guest-host interactions can result in structural changes in the porous host and shut down diffusion of one of the two similar guest molecules.

    • Dmytro Antypov
    • , Aleksander Shkurenko
    •  & Matthew S. Dyer
  • Article
    | Open Access

    Direct observation of carbon dioxide dissociation provides an origin of catalytic conversion for industrial chemical reactions. Here, the authors reveal their molecular interactions on the rhodium catalyst at near-ambient pressure by interface science techniques and computational calculations.

    • Jeongjin Kim
    • , Hyunwoo Ha
    •  & Jeong Young Park
  • Article
    | Open Access

    Protein structural dynamics can be studied by time-resolved crystallography (TRC) and ultrafast transient spectroscopic methods. Here, the authors perform electronic and vibrational transient absorption measurements to characterise the full photocycle of Photoactive Yellow Protein (PYP) both in the crystalline and solution state and find that the photocycle kinetics and structural intermediates of PYP deviate in the crystalline state, which must be taken into consideration when planning TRC experiments.

    • Patrick E. Konold
    • , Enis Arik
    •  & Marie Louise Groot
  • Article
    | Open Access

    Precise control over the energy of atomic metal sites is key to unlocking novel reaction pathways. Here, the authors achieve selective oxygen activation by the isolated copper site on ceria, due to its reduced 3d orbital energy via cerium induced electron withdrawing effect.

    • Liqun Kang
    • , Bolun Wang
    •  & Feng Ryan Wang
  • Article
    | Open Access

    Formation of peptide bonds in cold gas-phase environments might represent a prebiotic synthesis route of polypeptides. Here, the authors show the formation of up to tetra-peptide species in the collision of He2+ ions, with kinetic energies typical for solar wind ions, with cold β-alanine clusters.

    • Patrick Rousseau
    • , Dariusz G. Piekarski
    •  & Bernd A. Huber
  • Article
    | Open Access

    Imaging zeolites in catalysis relies on the use of probe molecules or model catalysts. Here the authors show the synergy of a multiscale reaction-diffusion model and structured illumination microscopy to illustrate spatiotemporal evolution of molecules and acid sites in SAPO-34 zeolites in methanol-to-olefins reaction.

    • Mingbin Gao
    • , Hua Li
    •  & Zhongmin Liu
  • Article
    | Open Access

    The geometric phase effect associated with a conical intersection between the ground and first excited electronic state has been predicted in the H3 system below the conical intersection energy. The authors, by a crossed molecular beam technique and quantum dynamic calculations, provide experimental evidence and insight into its origin.

    • Daofu Yuan
    • , Yin Huang
    •  & Xueming Yang
  • Article
    | Open Access

    How a catalyst behaves microscopically under reaction conditions, and what kinds of active sites transiently exist on its surface, is still very much a mystery to the scientific community. Here the authors report on in situ observation of a redox active copper catalyst by a combination of in situ imaging and spectroscopy tools.

    • Jing Cao
    • , Ali Rinaldi
    •  & Marc Willinger
  • Article
    | Open Access

    There are multiple ways by which energy and charge transfer occur in weakly bound systems. Here the authors reveal a heavy ion N+ transfer in a doubly charged Van der Waals cluster produced in collisions of the highly charged Ne8+ ion with N2Ar, leading to fragmentation of N+ and NAr+ via Coulomb explosion.

    • XiaoLong Zhu
    • , XiaoQing Hu
    •  & X. Ma
  • Article
    | Open Access

    In spite of numerous works, the nature of high activity of Cu/ZnO catalyst in methanol synthesis remains the subject of intensive debate. Here, the authors study the carbon dioxide hydrogenation mechanism using high-pressure operando techniques which allow them to unify different, seemingly contradicting, models.

    • Maxim Zabilskiy
    • , Vitaly L. Sushkevich
    •  & Jeroen A. van Bokhoven
  • Article
    | Open Access

    Reactions induced by low-energy electrons in hydrated systems are central to radiation therapy, but a full understanding of their mechanism is lacking. Here the authors investigate the electron-impact induced ionization and subsequent dissociation of tetrahydrofuran, model for biochemically relevant systems, in a micro-solvated environment.

    • Enliang Wang
    • , Xueguang Ren
    •  & Alexander Dorn
  • Article
    | Open Access

    The experimental observation that water dimers diffuse more rapidly than monomers across materials’ surfaces is yet to be clarified. Here the authors show by ab initio calculations classical and quantum mechanical mechanisms for faster water dimer diffusion on a broad range of metal and non-metal surfaces.

    • Wei Fang
    • , Ji Chen
    •  & Angelos Michaelides
  • Article
    | Open Access

    Unlike the homogeneous Wacker process, understanding of the mechanism of the heterogeneous system remains superficial. Here, the authors investigate the mechanism of heterogeneous Wacker oxidation over Pd-Cu/zeolite Y through the synergistic combination of kinetic, spectroscopic and chemometric studies.

    • Jerick Imbao
    • , Jeroen A. van Bokhoven
    •  & Maarten Nachtegaal
  • Article
    | Open Access

    Water confined in natural or synthetic hydrophobic nano-spaces behaves differently than in the bulk. Here the authors investigate water in hydrophobic synthetic 1D nanochannels revealing water clustering in tetramers and octamers and high proton conductivity, along with a continuous liquid to solid transition.

    • Ken-ichi Otake
    • , Kazuya Otsubo
    •  & Hiroshi Kitagawa
  • Article
    | Open Access

    The mechanism by which C-C bonds form during Fischer-Tropsch synthesis remains debated while spectroscopic identification of reaction intermediates remains scarce. Here, the authors identify alkylidynes as reactive intermediates for C-C bond formation on cobalt terrace sites and moreover show that these intermediates are stabilized by the high surface coverage typical for Fischer-Tropsch synthesis.

    • C. J. (Kees-Jan) Weststrate
    • , Devyani Sharma
    •  & J. W. (Hans) Niemantsverdriet
  • Article
    | Open Access

    Water molecular motion on surfaces underpins a range of phenomena in nature. The authors resolve the nanoscale-nanosecond motion of water at a topological insulator’s surface by helium spin-echo spectroscopy and computations, reporting hopping among sites and repulsion between water molecules.

    • Anton Tamtögl
    • , Marco Sacchi
    •  & William Allison
  • Article
    | Open Access

    Feshbach resonances are transiently trapped states along a reaction coordinate, providing a probe to the reaction’s potential energy surface (PES) but difficult to analyze in polyatomic systems. Here the authors identify Feshbach resonances in a reacting 4-atom system by state-to-state quantum dynamics using a full-dimensional PES.

    • Xiaoren Zhang
    • , Lulu Li
    •  & Dong H. Zhang
  • Article
    | Open Access

    Inverse kinetic isotope effects (KIEs) are rarely observed. Here, the authors report an inverse KIE in the charge transfer reaction of $${{\rm{Xe}}}^{+}$$Xe+ with ammonia. $${{\rm{ND}}}_{3}$$ND3 reacts more than 3 times faster than $${{\rm{NH}}}_{3}$$NH3, despite no N-H or N-D bonds being broken, with implications for our understanding of interstellar chemistry.

    • L. S. Petralia
    • , A. Tsikritea
    •  & B. R. Heazlewood
  • Article
    | Open Access

    Excited state aromaticity gives rise to unique photophysical properties which may aid the design of functional photoactive materials. Here, the authors spectroscopically characterize an acceptor-donor-acceptor system featuring a two-electron transfer process stabilized by aromatization in the lower energy excited state.

    • Jinseok Kim
    • , Juwon Oh
    •  & Dongho Kim
  • Article
    | Open Access

    Nanoconfinement effects on changing molecular transport and reaction kinetics in heterogeneous catalysis have been widely recognized. Here, the authors design a core-shell nanocatalyst with aligned linear nanopores to uncover nanoconfinement effects on catalytic activity and adsorption strength by single molecule imaging.

    • Bin Dong
    • , Yuchen Pei
    •  & Ning Fang
  • Article
    | Open Access

    Controlling selectivity between homochiral and heterochiral reaction pathways on surfaces is intriguing but challenging. Here, the authors demonstrate strategies in steering the reactions of prochiral terminal alkynes between the homochiral and heterochiral pathways by tuning the precursor substituents and the kinetic parameters.

    • Tao Wang
    • , Haifeng Lv
    •  & Junfa Zhu
  • Article
    | Open Access

    Detonation of high explosives can produce many nanocarbon allotropes and morphologies, but the mechanism of formation is challenging to explore. Here the authors observe, by time-resolved small-angle X-ray scattering, a transient liquid phase that precedes the formation of carbon onions.

    • M. Bagge-Hansen
    • , S. Bastea
    •  & T. M. Willey
  • Article
    | Open Access

    Electrophoretic mobility shift assays are widely used in gel electrophoresis to study binding interactions between different molecular species, but these assays access only a subset of reaction possibilities. Here, the authors develop a band-collision gel electrophoresis (BCGE) approach that demonstrates a much wider variety of reaction types.

    • Dimitri A. Bikos
    •  & Thomas G. Mason
  • Article
    | Open Access

    Nonadiabatic excited state processes involve mixing of electronic and nuclear wavefunctions, which are difficult to disentangle. Here the authors explore by time-resolved X-ray absorption near edge structure the wavepacket dynamics of a copper(I)-phenanthroline complex, resolving different vibrational modes.

    • Tetsuo Katayama
    • , Thomas Northey
    •  & Thomas J. Penfold
  • Article
    | Open Access

    Excited-state molecular dynamics may be too complex to be resolved by femtosecond spectroscopic studies. Here the authors resolve the competing pathways in the excited state dynamics of methyl bromide by attosecond transient absorption spectroscopy, from excitation to fragmentation.

    • Henry Timmers
    • , Xiaolei Zhu
    •  & Stephen R. Leone
  • Article
    | Open Access

    Ultracold polar molecules are an excellent platform for quantum science but experiments so far see fast trap losses that are poorly understood. Here the authors investigate collisional losses of nonreactive RbCs, and show they are consistent with the sticky collision hypothesis, but are slower than the universal rate.

    • Philip D. Gregory
    • , Matthew D. Frye
    •  & Simon L. Cornish
  • Article
    | Open Access

    Zero-field nuclear magnetic resonance can identify species and collective behaviors in mixtures without applied magnetic fields. Here the authors demonstrate its use for resolving proton exchange in ammonium and for the detection of hyperpolarized pyruvic acid, an important imaging biomarker.

    • Danila A. Barskiy
    • , Michael C. D. Tayler
    •  & Alexander Pines