摘要：Photochromic diarylethenes have been widely used in many fields. However, their cyclization process must be induced by UV light. In this article, a simple strategy is developed by extending π-conjugation with electron donating groups. The modified dirylethene derivative can photocyclolize under 405-nm light with a good photochromic efficiency. Meanwhile, its absorption and moderate fluorescence can be switched effectively in both directions by visible lights(405 and 520 nm, respectively) in different solutions and in living cells. We believe that this simple method will become a versatile strategy for developing various dirylethylenes with visible-light photochromism.

摘要：We have developed a compact photoelectron imaging facility, including an anion source with dissociative photoelectron attachment to molecules, a linear time-of-flight mass spec-trometry （TOFMS）, and an orthogonal high-resolution threshold photoelectron velocity map imaging spectrometer （VMI）. Intense and cold cluster anions were prepared in photoelectron- attachment processes upon pulsed UV laser ablation of metal target. Combining this anion source with TOFMS-VMI, the achieved mass resolution is about 200, and the electron ki- netic energy resolution is better than 3%, i.e., 30 meV for 1 eV electrons. More importantly, low-energy photoelectron imaging spectra for CH3S- and S2- at 611.46 nm are obtained. In both cases, the refined electron affinities are determined to be 1.86264-0.0020 eV for CH3S and 1.67444-0.0035 eV for S2, respectively. Preliminary results suggest that the apparatus is a powerful tool for estimating precise electron affinities values from threshold photoelectron imaging spectroscopy.

摘要：Photophysical processes occurring within organic semiconductors is important for designing and fabricating organic solar *** phthalocyanine(CuPc)is a typical electron *** this work,the triplet exciton lifetime is prolonged by altering the molecular stacking pattern of the CuPc *** CuPc thin films,the excited state decays are mainly determined by the triplet-triplet annihilation *** ultrafast transient absorption measurements indicate that the primary annihilation mechanism is one-dimensional exciton diffusion collision *** decay kinetics show a clearly time-dependent annihilation rate constant withγ∝t^(-1/2).Annihilation rate constants are determined to beγ0=(2.87±0.02)×10^(-20)cm^(3)·s^(-1/2)and(1.42±0.02)×10^(-20)cm^(3)·s^(-1/2)for upright and lyingdown configurations,*** to the CuPc thin film with an upright configuration,the thin film with a lying-down configuration shows longer exciton lifetime and higher absorbance,which are beneficial to organic solar *** results in this work have important implications on the design and mechanistic understanding of organic optoelectronic devices.

摘要：Covalent organic frameworks(COFs)are promising materials for converting solar energy into green ***,limited charge separation and transport in COFs impede their application in the photocatalytic hydrogen evolution reaction(HER).In this study,the intrinsically tunable internal bond electric field(IBEF)at the imine bonds of COFs was manipulated to cooperate with the internal molecular electric field(IMEF)induced by the donor-acceptor(D-A)structure for an efficient *** aligned orientation of IBEF and IMEF resulted in a remarkable H_(2) evolution rate of 57.3 mmol·g^(-1)·h^(-1)on TNCA,which was approximately 520 times higher than that of TCNA(0.11 mmol·g^(-1)·h^(-1))with the opposing electric field *** superposition of the dual electric fields enables the IBEF to function as an accelerating field for electron transfer,kinetically facilitat-ing the migration of photogenerated electrons from D to ***,theoretical calculations indicate that the inhomogeneous charge distribution at the C and N atoms in TNCA not only pro-vides a strong driving force for carrier transfer but also effectively hinders the return of free elec-trons to the valence band,improving the utilization of *** strategy of fabricating dual electric fields in COFs offers a novel approach to designing photocatalysts for clean energy synthesis.

摘要：Intrinsic broadband photoluminescence(PL)of self-trapped excitons(STEs)are systematically studied in lead-free double perovskite nanocrystals(NCs).It is clarified that bandgap(direct/indirect)has important influence on the PL properties of STEs:indirect bandgap NCs exhibit strong exciton-phonon coupling which results in non-radiative STEs,while direct bandgap NCs exhibit moderate exciton-phonon coupling,inducing bright STE ***,by alloying K+and Li+ions in Cs2AgInCl6 NCs,the NCs exhibit broadband white-light ***-carrier dynamics study indicates that the efficient white-light emission originates from the further suppressed non-radiative processes of the STEs in the direct bandgap *** work may deepen the understanding of STEs and guide the design of highperformance lead-free perovskites.

摘要：Anchoring molecular cocatalysts on semiconductors has been recognized as a general strategy to boost the charge separation efficiency required for efficient ***,the effect of molecular cocatalysts on energy funneling(i.e.,directional energy transfer)inside semiconductor photocatalysts has not been demonstrated *** we prepared CdS nanorods with both thin and thick rods and anchored the conjugated molecules 2‐mercaptobenzimidazole(MBI)and cobalt molecular catalysts(MCoA)sequentially onto the surface of *** absorption measurements revealed that MBI molecules facilitated energy funneling from thin to thick rods by the electronic coupling between thin and thick nanorods,which is essentially a light‐harvesting antenna approach to enhance the charge generation efficiency in the reaction center(here the thick rods).Moreover,MBI and MCoA molecules selectively extracted photogenerated holes and electrons of CdS nanorods rapidly,leading to efficient charge ***,CdS/MBI/MCoA displayed 15 times enhanced photocatalytic H_(2) evolution(1.65 mL)than pure CdS(0.11 mL)over 3 h of *** amount of H_(2) evolution reached 60 mL over 48 h of illumination with a high turnover number of 26294 and an apparent quantum efficiency of 71%at 420 *** study demonstrates a novel design principle for next‐generation photocatalysts.

摘要：Ruthenium(Ru)serves as a promising catalyst for ammonia synthesis via the Haber-Bosch process,identification of the structure sensitivity to improve the activity of Ru is important but not fully explored *** present here density functional theory calculations combined with microkinetic simulations on nitrogen molecule activation,a crucial step in ammonia synthesis,over a variety of hexagonal close-packed(hcp)and face-center cubic(fcc)Ru ***{2130}facet exhibits the highest activity toward N_(2) dissociation in hcp Ru,followed by the(0001)monatomic step *** other hcp Ru facets have N_(2) dissociation rates at least three orders ***{211}facet shows the best performance for N_(2) activation in fcc Ru,followed by{311},which indicates stepped surfaces make great contributions to the overall *** hcp Ru{2130}facet and(0001)monatomic step sites have lower or comparable activation barriers compared with fcc Ru{211}facet,fcc Ru is proposed to be more active than hcp Ru for N_(2) conversion due to the exposure of the more favorable active sites over step surfaces in fcc *** work provides new insights into the crystal structure sensitivity of N_(2) activation for mechanistic understanding and rational design of ammonia synthesis over Ru catalysts.

摘要：Dissociative adsorption of HCl on Au(111)has become one of unsolved puzzles in surface *** tremendous efforts in the past years,varioustheoretical models still greatly overestimate the zero-coverage initial sticking probabilities(So).To find the origin of the large experiment-theory discrepancy,we have revisited the dissociative adsorption of HCl on Au(111)with a newly designed molecular beam-surface *** zero-coverage So derived from Cl-coverage measurements with varying HCl doses agree well with previous ***,we notice a sharp change of the coverage/dose slope with the HCl dosage at the low coverage regime,which may result in some uncertainties to the fitted So *** seems consistent with a coverage-dependence of the dissociation barrier predicted by density functional theory at low *** results reveal the potential inconsistency of utilizing simulations with finite coverage to compare against experimental data with zero coverage in this system,and provide guidance for improving both experiment and theory in this regard.