Research Highlights
Pei-Ling Luo
Accurate kinetic studies of OH + HO2 radical–radical reaction through direct measurement of precursor and radical concentrations with high-resolution time-resolved dual-comb spectroscopy
I-Yun Chen, Che-Wei Chang, Christa Fittschen, and Pei-Ling Luo*
The radical–radical reaction between OH and HO2 has been considered for a long time as an important reaction in tropospheric photochemistry and combustion chemistry. However, a significant discrepancy of an order of magnitude for rate coefficients of this reaction is found between two recent experiments. Herein, we investigate the reaction OH + HO2 via direct spectral quantification of both the precursor (H2O2) and free radicals (OH and HO2) upon the 248 nm photolysis of H2O2 using infrared two-color time-resolved dual-comb spectroscopy. With quantitative and kinetic analysis of concentration profiles of both OH and HO2 at varied conditions, the rate coefficient kOH+HO2 is determined to be (1.10 ± 0.12) × 10–10 cm3 molecule–1 s–1 at 296 K. Moreover, we explore the kinetics of this reaction under conditions in the presence of water, but no enhancement in the kOH+HO2 can be observed. This work as an independent experiment plays a crucial role in revisiting this prototypical radical–radical reaction.
Hsiang-Hua Jen
Generating scalable graph states in an atom-nanophotonic interface
C.-H. Chien, S. Goswami, C.-C. Wu, W.-S. Hiew, Y.-C. Chen, and H. H. Jen
Scalable graph states are essential for measurement-based quantum computation and many entanglement-assisted applications in quantum technologies. Generation of these multipartite entangled states requires a controllable and efficient quantum device with delicate design of generation protocol. Here we propose to prepare high-fidelity and scalable graph states in one and two dimensions, which can be tailored in an atom-nanophotonic cavity via state carving technique. We propose a systematic protocol to carve out unwanted state components, which facilitates scalable graph states generations via adiabatic transport of a definite number of atoms in optical tweezers. An analysis of state fidelity is also presented, and the state preparation probability can be optimized via multiqubit state carvings and sequential single-photon probes. Our results showcase the capability of an atom-nanophotonic interface for creating graph states and pave the way toward novel problem-specific applications using scalable high-dimensional graph states with stationary qubits.
Huan-Cheng Chang
Imaging Extreme Ultraviolet Radiation Using Nanodiamonds with Nitrogen-Vacancy Centers
Teng-I Yang,1 Yuen Yung Hui,1 Jen-Iu Lo,2 Yu-Wen Huang,1 Yin-Yu Lee,3 Bing-Ming Cheng,2,4,* and Huan-Cheng Chang1,5,6,

1Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei City 106319, Taiwan
2Department of Medical Research, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien City 970, Taiwan
3National Synchrotron Radiation Research Center, Hsinchu City 300092, Taiwan
4Tzu-Chi University of Science and Technology, Hualien City 970, Taiwan
5Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei City 106335, Taiwan
6Department of Chemistry, National Taiwan Normal University, Taipei City 106, Taiwan
Extreme ultraviolet (EUV) radiation with wavelengths of 10 – 121 nm has drawn considerable attention recently for its use in photolithography to fabricate nanoelectronic chips.  This study demonstrates, for the first time, fluorescent nanodiamonds (FNDs) with nitrogen-vacancy (NV) centers as scintillators to image and characterize EUV radiations.  The FNDs employed are ~100 nm in size; they form a uniform and stable thin film on an indium tin oxide-coated slide by electrospray deposition.  The film is non-hygroscopic, photostable, and can emit bright red fluorescence from NV0 centers when excited by EUV light.  An FND-based imaging device has been developed and applied for beam diagnostics of 50 nm and 13.5 nm synchrotron radiations, achieving a spatial resolution of 30 μm using a film of ~1 μm thickness.  The noise equivalent power density is 29 μW/cm2Hz1/2 for the 13.5 nm radiation.  The method is generally applicable to imaging EUV radiations from different sources. 
Pei-Ling Luo
Direct gas-phase formation of formic acid through reaction of Criegee intermediates with formaldehyde
Pei-Ling Luo*, I-Yun Chen, M. Anwar H. Khan, and Dudley E. Shallcross
Ozonolysis of isoprene is considered to be an important source of formic acid (HCOOH), but its underlying reaction mechanisms related to HCOOH formation are poorly understood. Here, we report the kinetic and product studies of the reaction between the simplest Criegee intermediate (CH2OO) and formaldehyde (HCHO), both of which are the primary products formed in ozonolysis of isoprene. By utilizing time-resolved infrared laser spectrometry with the multifunctional dual-comb spectrometers, the rate coefficient kCH2OO+HCHO is determined to be (4.11 ± 0.25) × 10−12 cm3 molecule−1 s−1 at 296 K and a negative temperature dependence of the rate coefficient is observed and described by an Arrhenius expression with an activation energy of (–1.81 ± 0.04) kcal mol−1. Moreover, the branching ratios of the reaction products HCOOH + HCHO and CO + H2O + HCHO are explored. The yield of HCOOH is obtained to be 37–54% over the pressure (15–60 Torr) and temperature (283–313 K) ranges. The atmospheric implications of the reaction CH2OO + HCHO are also evaluated by incorporating these results into a global chemistry-transport model. In the upper troposphere, the percent loss of CH2OO by HCHO is found by up to 6% which can subsequently increase HCOOH mixing ratios by up to 2% during December-January-February months.
Liang-Yan Hsu
Effects of Non-Adiabatic Electromagnetic Vacuum Fluctuations on Internal Conversion
Hung-Sheng Tsai, Chih-En Shen, Sheng-Chieh Hsu, and Liang-Yan Hsu*
To explore non-adiabatic effects caused by electromagnetic (EM) vacuum fluctuations in molecules, we develop a general theory of internal conversion (IC) in the framework of quantum electrodynamics and propose a new mechanism, “quantum electrodynamic internal conversion” (QED-IC). The theory allows us to compute the rates of the conventional IC and QED-IC processes at the first-principles level. Our simulations manifest that, under experimentally feasible weak light–matter coupling conditions, EM vacuum fluctuations can significantly affect IC rates by an order of magnitude. Moreover, our theory elucidates three key factors in the QED-IC mechanism: the effective mode volume, coupling-weighted normal mode alignment, and molecular rigidity. The theory successfully captures the nucleus–photon interaction in the factor “coupling-weighted normal mode alignment”. In addition, we find that molecular rigidity plays a totally different role in conventional IC versus QED-IC rates. Our study provides applicable design principles for exploiting QED effects on IC processes.
Charles Pin-Kuang Lai
Membrane Protein Modification Modulates Big and Small Extracellular Vesicle Biodistribution and Tumorigenic Potential in Breast Cancers in vivo
Bryan John Abel MagolingAnthony Yan-Tang WuYen-Ju ChenWendy Wan-Ting WongSteven Ting-Yu ChuoHsi-Chien HuangYun-Chieh SungHsin Tzu HsiehPoya HuangKang-Zhang LeeKuan-Wei HuangRuey-Hwa ChenYunching ChenCharles Pin-Kuang Lai
Our latest publication employed PalmGRET, a bioluminescence-resonance-energy-transfer (BRET)-based EV reporter, to discover an abundant release of big EVs (bEVs; >200 nm) by aggressive breast cancers when compared to epithelial and less malignant cells. bEVs have been largely overshadowed by small EVs (sEVs; <200 nm) in EV research in the past decades. This is the first study to accurately detect and systematically compare biophysical property and in vivo profiles of breast cancer bEVs and sEVs. This is followed by the identification of EV surface oncoproteins, and their role in modulating organotropism and tumorigenic potential of the bEVs and sEVs. Our landmark findings impart a broad and deep reference for upcoming EV studies, with an emphasis on EV engineering for diagnosis and therapeutic applications.
Wei-Hua Wang
Phase Modulation of Self-Gating in Ionic Liquid-Functionalized InSe Field-Effect Transistors
Chih-Yi Cheng, Wei-Liang Pai, Yi-Hsun Chen, Naomi Tabudlong Paylaga, Pin-Yun Wu, Chun-Wei Chen, Chi-Te Liang, Fang-Cheng Chou, Raman Sankar, Michael S. Fuhrer, Shao-Yu Chen*, and Wei-Hua Wang*
Understanding the Coulomb interactions between two-dimensional (2D) materials and adjacent ions/impurities is essential to realizing 2D material-based hybrid devices. Electrostatic gating via ionic liquids (ILs) has been employed to study the properties of 2D materials. However, the intrinsic interactions between 2D materials and ILs are rarely addressed. This work studies the intersystem Coulomb interactions in IL-functionalized InSe field-effect transistors by displacement current measurements. We uncover a strong self-gating effect that yields a 50-fold enhancement in interfacial capacitance, reaching 550 nF/cm2 in the maximum. Moreover, we reveal the IL-phase-dependent transport characteristics, including the channel current, carrier mobility, and density, substantiating the self-gating at the InSe/IL interface. The dominance of self-gating in the rubber phase is attributed to the correlation between the intra- and intersystem Coulomb interactions, further confirmed by Raman spectroscopy. This study provides insights into the capacitive coupling at the InSe/IL interface, paving the way to developing liquid/2D material hybrid devices.
Kuei-Hsien Chen
Boosting photocatalytic CO2 reduction in a ZnS/ZnIn2S4 heterostructure through strain-induced direct Z-scheme and a mechanistic study of molecular CO2 interaction thereon
Amr Sabbah, Indrajit Shown*, Mohammad Qorbani, Fang-Yu Fu, Tsai-Yu Lin, Heng-Liang Wu, Po-Wen Chung, Chih-I. Wu, Svette Reina Merden Santiago, Ji-Lin Shen, Kuei-Hsien Chen*, Li-Chyong Chen*
Employing direct Z-scheme semiconductor heterostructures in photocatalysis offers efficient charge carrier separation and isolation of both redox reactions, thus beneficial to reduce CO2 into solar fuels. Here, a ZnS/ZnIn2S4 heterostructure, comprising cubic ZnS nanocrystals on hexagonal ZnIn2S4 (ZIS) nanosheets, is successfully fabricated in a single-pot hydrothermal approach. The composite ZnS/ZnIn2S4 exhibits microstrain at its interface with an electric field favorable for Z-scheme. At an optimum ratio of Zn:In (~ 1:0.5), an excellent photochemical quantum efficiency of around 0.8% is reached, nearly 200-fold boost compared with pristine ZnS. Electronic levels and band alignments are deduced from ultraviolet photoemission spectroscopy and UV-Vis. Evidence of the direct Z-scheme and carrier dynamics is verified by photo-reduction experiment, along with photoluminescence (PL) and time-resolved PL. Finally, diffuse-reflectance infrared Fourier transformed spectroscopy explores the CO2 and related intermediate species adsorbed on the catalyst during the photocatalytic reaction. This microstrain-induced direct Z-scheme approach opens a new pathway for developing next-generation photocatalysts for CO2 reduction.
Liang-Yan Hsu
Cavity-Free Quantum-Electrodynamic Electron Transfer Reactions
Yu-Chen Wei and Liang-Yan Hsu*
Richard Feynman stated that “The theory behind chemistry is quantum electrodynamics”. However, harnessing quantum-electrodynamic (QED) effects to modify chemical reactions is a grand challenge and currently has only been reported in experiments using cavities due to the limitation of strong light–matter coupling. In this article, we demonstrate that QED effects can significantly enhance the rate of electron transfer (ET) by several orders of magnitude in the absence of cavities, which is implicitly supported by experimental reports. To understand how cavity-free QED effects are involved in ET reactions, we incorporate the effect of infinite one-photon states into Marcus theory, derive an explicit expression for the rate of radiative ET, and develop the concept of “electron transfer overlap”. Moreover, QED effects may lead to a barrier-free ET reaction whose rate is dependent on the energy-gap power law. This study thus provides new insights into fundamental chemical principles, with promising prospects for QED-based chemical reactions.
Hsiang-Hua Jen
A non-Hermitian optical atomic mirror
Yi-Cheng Wang, Jhih-Shih You & H. H. Jen
Explorations of symmetry and topology have led to important breakthroughs in quantum optics, but much richer behaviors arise from the non-Hermitian nature of light-matter interactions. A high-reflectivity, non-Hermitian optical mirror can be realized by a two-dimensional subwavelength array of neutral atoms near the cooperative resonance associated with the collective dipole modes. Here we show that exceptional points develop from a nondefective degeneracy by lowering the crystal symmetry of a square atomic lattice, and dispersive bulk Fermi arcs that originate from exceptional points are truncated by the light cone. From its nontrivial energy spectra topology, we demonstrate that the geometry-dependent non-Hermitian skin effect emerges in a ribbon geometry. Furthermore, skin modes localized at a boundary show a scale-free behavior that stems from the long-range interaction and whose mechanism goes beyond the framework of non-Bloch band theory. Our work opens the door to the study of the interplay among non-Hermiticity, topology, and long-range interaction.
Tsyr-Yan Yu
Direct investigation of the reorientational dynamics of A-site cations in 2D organic-inorganic hybrid perovskite by solid-state NMR
Cheng-Chieh Lin, Shing-Jong Huang, Pei-Hao Wu, Tzu-Pei Chen, Chih-Ying Huang, Ying-Chiao Wang, Po-Tuan Chen, Denitsa Radeva, Ognyan Petrov, Vladimir Gelev, Raman Sankar, Chia-Chun Chen,
Chun-Wei Chen*, Tsyr-Yan Yu*
Limited methods are available for investigating the reorientational dynamics of A-site cations in two-dimensional organic–inorganic hybrid perovskites (2D OIHPs), which play a pivotal role in determining their physical properties. Here, we describe an approach to study the dynamics of A-site cations using solid-state NMR and stable isotope labelling. 2H NMR of 2D OIHPs incorporating methyl-d3-ammonium cations (d3-MA) reveals the existence of multiple modes of reorientational motions of MA. Rotational-echo double resonance (REDOR) NMR of 2D OIHPs incorporating 15N- and 13C-labeled methylammonium cations (13C,15N-MA) reflects the averaged dipolar coupling between the C and N nuclei undergoing different modes of motions. Our study reveals the interplay between the A-site cation dynamics and the structural rigidity of the organic spacers, so providing a molecular-level insight into the design of 2D OIHPs.
Chia-Lung Hsieh
Label-Free Dynamic Imaging of Chromatin in Live Cell Nuclei by High-Speed Scattering-Based Interference Microscopy
Yi-Teng Hsiao, Chia-Ni Tsai, Te-Hsin Chen, Chia-Lung Hsieh*
Chromatin is a DNA–protein complex that is densely packed in the cell nucleus. The nanoscale chromatin compaction plays critical roles in the modulation of cell nuclear processes. However, little is known about the spatiotemporal dynamics of chromatin compaction states because it remains difficult to quantitatively measure the chromatin compaction level in live cells. Here, we demonstrate a strategy, referenced as DYNAMICS imaging, for mapping chromatin organization in live cell nuclei by analyzing the dynamic scattering signal of molecular fluctuations. Highly sensitive optical interference microscopy, coherent brightfield (COBRI) microscopy, is implemented to detect the linear scattering of unlabeled chromatin at a high speed. A theoretical model is established to determine the local chromatin density from the statistical fluctuation of the measured scattering signal. DYNAMICS imaging allows us to reconstruct a speckle-free nucleus map that is highly correlated to the fluorescence chromatin image. Moreover, together with calibration based on nanoparticle colloids, we show that the DYNAMICS signal is sensitive to the chromatin compaction level at the nanoscale. We confirm the effectiveness of DYNAMICS imaging in detecting the condensation and decondensation of chromatin induced by chemical drug treatments. Importantly, the stable scattering signal supports a continuous observation of the chromatin condensation and decondensation processes for more than 1 h. Using this technique, we detect transient and nanoscopic chromatin condensation events occurring on a time scale of a few seconds. Label-free DYNAMICS imaging offers the opportunity to investigate chromatin conformational dynamics and to explore their significance in various gene activities.Link to the paper: in Faculty Opinion: by Science Promotion & Engagement Center: 
Ya-Ping Hsieh
Ferroelectric 2D ice under graphene confinement
Hao-Ting Chin, Jiri Klimes, I-Fan Hu, Ding-Rui Chen, Hai-Thai Nguyen, Ting-Wei Chen, Shao-Wei Ma, Mario Hofmann, Chi-Te Liang & Ya-Ping Hsieh
We here report on the direct observation of ferroelectric properties of water ice in its 2D phase. Upon nanoelectromechanical confinement between two graphene layers, water forms a 2D ice phase at room temperature that exhibits a strong and permanent dipole which depends on the previously applied field, representing clear evidence for ferroelectric ordering. Characterization of this permanent polarization with respect to varying water partial pressure and temperature reveals the importance of forming a monolayer of 2D ice for ferroelectric ordering which agrees with ab-initio and molecular dynamics simulations conducted. The observed robust ferroelectric properties of 2D ice enable novel nanoelectromechanical devices that exhibit memristive properties. A unique bipolar mechanical switching behavior is observed where previous charging history controls the transition voltage between low-resistance and high-resistance state. This advance enables the realization of rugged, non-volatile, mechanical memory exhibiting switching ratios of 106, 4 bit storage capabilities and no degradation after 10,000 switching cycles.
Ya-Ping Hsieh
2D mechano-thermoelectric heterojunctions for self-powered strain sensors
Ying-Yu Wang, Ding-Rui Chen, Jen-Kai Wu, Tian-Hsin Wang, Chiashain Chuang, Ssu-Yen Huang, Wen-Pin Hsieh, Mario Hofmann, Yuan-Huei Chang, Ya-Ping Hsieh*
We here demonstrate the multifunctional properties of atomically thin heterojunctions that are enabled by strong interfacial interactions and their integration into ultra-high performance, self-powered sensors. Epitaxial alignment between tin diselenide and graphene through direct growth produces thermoelectric and mechanoelectric properties beyond the ability of either component. An unprecedented ZT of 2.43 originated from the synergistic combination of graphene’s high carrier conductivity and SnSe2 mediated thermal conductivity lowering. Moreover, strong interaction at the SnSe2/graphene interface produces stress localization that results in a novel 2D-crack-assisted strain sensing mechanism whose sensitivity (GF=450) is superior to all other 2D materials. Finally, the graphene-assisted growth process, permits the formation of high-quality heterojunctions directly on polymeric substrates for flexible and transparent self-powered sensors that achieve fast and reliable strain sensing from a small temperature gradient. Our work enhances the fundamental understanding of multifunctionality at the atomic scale and provide a route towards structural health monitoring through ubiquitous and smart devices.
Charles Pin-Kuang Lai
Multiplexed bioluminescence-mediated tracking of DNA double strand break repairs in vitro and in vivo
Jasper Che-Yung Chien, Christian E. Badr* and Charles Pin-Kuang Lai*
The dynamics of DNA double-strand break (DSB) repairs including homology-directed repair and nonhomologous end joining play an important role in diseases and therapies. However, investigating DSB repair is typically a low-throughput and cross-sectional process, requiring disruption of cells and organisms for subsequent nuclease-, sequencing- or reporter-based assays. In this protocol, we provide instructions for establishing a bioluminescent repair reporter system using engineered Gaussia and Vargula luciferases for noninvasive tracking of homology-directed repair and nonhomologous end joining, respectively, induced by SceI meganuclease, SpCas9 or SpCas9 D10A nickase-mediated editing. We also describe complementation with orthogonal DSB repair assays and omics analyses to validate the reporter readouts. The bioluminescent repair reporter system provides longitudinal and rapid readout (~seconds per sample) to accurately and efficiently measure the efficacy of genome-editing tools and small-molecule modulators on DSB repair. This protocol takes ~2–4 weeks to establish, and as little as 2 h to complete the assay. The entire bioluminescent repair reporter procedure can be performed by one person with standard molecular biology expertise and equipment. However, orthogonal DNA repair assays would require a specialized facility that performs Sanger sequencing or next-generation sequencing.
Yang-hao Chan
Giant exciton-enhanced shift currents and direct current conduction with subbandgap photo excitations produced by many-electron interactions
Y. H. Chan, Diana Y. Qiu, Felipe H. da Jornada, and Steven G. Louie
Shift current is a direct current generated from nonlinear light–matter interaction in a noncentrosymmetric crystal and is considered a promising candidate for next-generation photovoltaic devices. The mechanism for shift currents in real materials is, however, still not well understood, especially if electron–hole interactions are included. Here, we employ a first-principles interacting Green’s-function approach on the Keldysh contour with real-time propagation to study photocurrents generated by nonlinear optical processes under continuous wave illumination in real materials. We demonstrate a strong direct current shift current at subbandgap excitation frequencies in monolayer GeS due to strongly bound excitons, as well as a giant excitonic enhancement in the shift current coefficients at above bandgap photon frequencies. Our results suggest that atomically thin two-dimensional materials may be promising building blocks for next-generation shift current devices.