Recently,the LHCb experimental group found an exotic state T_(cc)^(+) from the pp→D^(0)D^(0)π^(+)+X process.A key question is whether it is just a molecule or may have a confined tetraquark ingredient.To investigate...Recently,the LHCb experimental group found an exotic state T_(cc)^(+) from the pp→D^(0)D^(0)π^(+)+X process.A key question is whether it is just a molecule or may have a confined tetraquark ingredient.To investigate this,different methods were used,including a two-channel(D^(∗)+D^(0) and D^(∗)0D^(+))K-matrix unitarization and a single-channel Flatté-like parametrization method analyzed utilizing the pole counting rule and spectral density function sum rule.These analyses demonstrated that T_(cc)^(+) is a molecular state,although the possibility that there may exist an elementary ingredient cannot be excluded,according to an approximate analysis of its production rate.展开更多
The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices.In this work,we propose theoretically and realize ...The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices.In this work,we propose theoretically and realize experimentally unidirectional perfect absorption in a non-Hermitian acoustic system with the help of the topological bound state in the continuum(BIC),which is established by the hybrid interaction between one trivial BIC and another conventional resonant state.In the 2D parameter space spanned by frequency and distance between the two resonators,the topological scattering singularities appear in pairs and are associated with topological distinguished charges.Meanwhile,we reveal the origin of topological charges and their continuous evolution with the loss factor.At a specific loss factor,two topological charges just annihilate together,and acoustic perfect absorption induced by topological BIC is realized at the left incidence,while there is no phase singularity and near-total reflection is observed at the right incidence,hence the system presents extreme asymmetry.Our work bridges the gap between scattering characteristics of non-Hermitian acoustic systems and topological scattering singularities,which may contribute to the research of novel non-Hermitian physics and the practical applications of advanced absorbers and sensors.展开更多
By using an approximation for the centrifugal term, we study relativistic bound and scattering states of spin-zero particles in the presence of equal scalar and vector modified Schioberg plus Manning–Rosen potentials...By using an approximation for the centrifugal term, we study relativistic bound and scattering states of spin-zero particles in the presence of equal scalar and vector modified Schioberg plus Manning–Rosen potentials for any quantum numbers n and l. Energy eigenvalues and the scattering amplitude are calculated. Some special cases of the problem are also investigated.展开更多
The polarization dependences of gain and amplified spontaneous Brillouin scattering(ABS) noise for fiber Brillouin amplifier(FBA) are analyzed through theories, simulations, and experiments.Modified vector propagation...The polarization dependences of gain and amplified spontaneous Brillouin scattering(ABS) noise for fiber Brillouin amplifier(FBA) are analyzed through theories, simulations, and experiments.Modified vector propagation equations for calculating the gain of the probe signal and the ABS noise are derived and analyzed in the Stokes spaces.In simulations and experiments, we prove that the gain of the probe signal and the ABS noise are strongly dependent on the relative state of polarization(SOP) of the pump and probe signals.The closer the relative SOP of the pump and probe signals is, the more obvious ABS noise suppression effect will be brought by increasing the power of the input probe signal.展开更多
Thermal neutron inelastic scattering experiments have been successfully used tostudy the lattice dynamics of the classical crystalline invar alloys. Y. Endoh et al. havesystematically investigated the temperature depe...Thermal neutron inelastic scattering experiments have been successfully used tostudy the lattice dynamics of the classical crystalline invar alloys. Y. Endoh et al. havesystematically investigated the temperature dependence of the phonon dispersion forthe Fe-based crystalline invar alloys Fe<sub>65</sub>Ni<sub>35</sub>, Fe<sub>3</sub>Pt and Fe<sub>70</sub>Mn<sub>30</sub> by inelasticneutron scattering, and found that the transverse acoustic-phonon modes become softbelow the magnetic transition temperature. It is suggested that the phonon softeningof these invar alloys may be attributed to the enhancement of展开更多
The edges of two-dimensional(2D)materials can exhibit special structure and thus distinctive properties differing from the interior,such as the modified photoluminescence emission,the improved electrocatalytic activit...The edges of two-dimensional(2D)materials can exhibit special structure and thus distinctive properties differing from the interior,such as the modified photoluminescence emission,the improved electrocatalytic activity,and the enhanced nonlinear optical response.In this work,we report the observation of abrupt enhancement of Raman scattered light at edges of layered MoS_(2),which is closely related to the polarization of the incident light.More importantly,the intensity of out-of-plane A1g mode is enhanced much more obviously than the in-plane E_(2g)^(1)mode.The unique optical effect at edges is also reflected on the alteration of Raman selection rule.The forbidden Raman modes are observed at edge region,and the polarization of Raman scattered light can be modulated by the edge structure,which differs obviously from that of the interior.We attribute these particular performances to the modulation of the intensity and distribution of the electric field for the incident and Raman scattered light at the edge.This work provides a systematic research on the intensity and polarization modulation of the Raman scattering at edges,which would be helpful for understanding the distinctive optical properties of the edge structure.展开更多
A crossed molecular beams, state-to-state scattering study was carried out on the F＋H2→HF＋H reaction at the collision energy of 5.02 kJ/mol, using the highly sensitive H atom Rydberg tagging time-of-flight method. ...A crossed molecular beams, state-to-state scattering study was carried out on the F＋H2→HF＋H reaction at the collision energy of 5.02 kJ/mol, using the highly sensitive H atom Rydberg tagging time-of-flight method. All the peaks in the TOF spectra can be clearly assigned to the ro-vibrational structures of the HF product. The forward scattering of the HF product at v′=3 has been observed. The small forward scattering of the HF product at v′=2 has also been detected. Detailed theoretical analysis is required in order to fully understand the dynamical origin of these forward scattering products at this high collision energy.展开更多
In-situ characterization of non-aqueous nano-dispersion systems（NANDS） by freeze-etching transmission electron microscope（FETEM） was reported.To improve just-for-once successive rate of specimen preparation and ge...In-situ characterization of non-aqueous nano-dispersion systems（NANDS） by freeze-etching transmission electron microscope（FETEM） was reported.To improve just-for-once successive rate of specimen preparation and get good characterization results,an improving specimen preparation method of freezing etching was developed.Size,distribution and morphology of NANDS were directly visualized.Some information of particle dispersion feature and particle density can also be obtained.Reproductivity of the FETEM characterization is excellent.Comparing with laser scattering method,which is liable to give positive error especially for small size particle anchoring disperser,FETEM characterization can give more accurate measurement of particle size.Moreover,FETEM can give dispersion feature of nanoparticle in non-aqueous medium.展开更多
The evolution of electron correlation and charge density wave （CDW） in 1T-TaS2 single crystal has been investi- gated by temperature-dependent Raman scattering, which undergoes two obvious peaks of Aig modes about 7...The evolution of electron correlation and charge density wave （CDW） in 1T-TaS2 single crystal has been investi- gated by temperature-dependent Raman scattering, which undergoes two obvious peaks of Aig modes about 70.8 cm-t and 78.7 cm I at 80 K, respectively. The former peak at 70.8 cm-t is accordant with the lower Hubbard band, resulting in the electron-correlation-driven Mott transition. Strikingly, the latter peak at 78.7 cm-1 shifts toward low energy with increasing the temperature, demonstrating the occurrence of nearly commensurate CDW phase （melted Mott phase）. In this case, phonon transmission could be strongly coupled to commensurate CDW lattice via Coulomb interaction, which likely induces appearance of hexagonal domains suspended in an interdomain phase, composing the melted Mott phase characterized by a shallow electron pocket. Combining electronic structure, atomic structure, transport properties with Ra- man scattering, these findings provide a novel dimension in understanding the relationship between electronic correlation, charge order, and phonon dynamics.展开更多
The comparison between single-point energy scanning （SPES） and geometry optimization （OPT） in determining the equilibrium geometry of the α^3∑u^＋ state for ^7Li2 is made at numerous basis sets such as 6-311＋＋...The comparison between single-point energy scanning （SPES） and geometry optimization （OPT） in determining the equilibrium geometry of the α^3∑u^＋ state for ^7Li2 is made at numerous basis sets such as 6-311＋＋G（2df）, cc-PVTZ, 6-311＋＋G（2df, p）, 6-311G（3df,3pd）, 6-311＋＋G（2df,2pd）, D95（3df,3pd）, 6-311＋＋G, DGDZVP, 6-311＋＋G（3df,2pd）, 6-311G（2df,2pd）, D95V＋＋, CEP-121G, 6-311＋＋G（d,p）, 6-311＋＋G（2df, pd） and 6-311＋＋G（3df,3pd） in full active space using a symmetry-adapted-cluster/ symmetry-adapted-cluster configuration-interaction （SAC/SAC=CI） method presented in Gaussian03 program package. The difference of the equilibrium geometries obtained by SPES and by OPT is reported. Analyses show that the results obtained by SPES are more reasonable than those obtained by OPT. We have calculated the complete potential energy curves at those sets over a wide internuclear distance range from about 3.0α0 to 37.0α0, and the conclusion is that the basis set cc-PVTZ is the most suitable one. With the potential obtained at ccopVTZ, the spectroscopic data （Te, De, D0, ωe,ωeХe, αe and Be） are computed and they are 1.006 eV, 338.71 cm^-1, 307.12 cm^-1, 64.88 cm^-1, 3.41 cm^-1, 0.0187 cm^-1 and 0.279 cm^-1, respectively, which are in good agreement with recent measurements. The total 11 vibrational states are found at J=0. Their corresponding vibrational levels and classical turning points are computed and compared with available RKR data, and good agreement is found. One inertial rotation constant （By） and six centrifugal distortion constants （Dr Hv, Lv, My, Nv, and Ov） are calculated. The scattering length is calculated to be -27.138α0, which is in good accord with the experimental data.展开更多
The interactions of non-ionic amphiphilic diblock copolymer poly（oxyethylene/oxybutylene） （E39B18） with anionic surfactant sodium dodecyl sulphate （SDS） and cationic surfactant hexadecyltrimethylammonium bromide...The interactions of non-ionic amphiphilic diblock copolymer poly（oxyethylene/oxybutylene） （E39B18） with anionic surfactant sodium dodecyl sulphate （SDS） and cationic surfactant hexadecyltrimethylammonium bromide （CTAB） were studied by using various techniques such as surface tension, conductivity, steady-state fluorescence and dynamic light scattering. Surface tension measurements were used to determine the critical micelle concentration （CMC） and thereby the free energy of micellization （AGmic）, free energy of adsorption （AG^ds）, surface excess concentration （F） and minimum area per molecule （A）. Conductivity measurements were used to determine the critical micelle concentration （CMC）, critical aggregation concentration （CAC）, polymer saturation point （PSP）, degree of ionization （tr） and counter ion binding （l]）. Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants. The ratio of the first and third vibronic peaks （11/Is） indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions. Aggregation number （N）, number of binding sites （n） and free energy of binding （AGb） for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.展开更多
Topological insulators as a new type of quantum matter materials are characterized by a full insulating gap in the bulk and gapless edge/surface states protected by the time-reversal symmetry. We propose that the inte...Topological insulators as a new type of quantum matter materials are characterized by a full insulating gap in the bulk and gapless edge/surface states protected by the time-reversal symmetry. We propose that the interference patterns caused by the elastic scattering of defects or impurities are dominated by the surface states at the extremal points on the constant energy contour. Within such a formalism, we summarize our recent theoretical investigations on the elastic scattering of topological surface states by various imperfections, including non-magnetic impurities, magnetic impurities, step edges, and various other defects, in comparison with the recent related experiments in typical topological materials such as BiSb alloys, Bi2Te3, and Bi2Se3 crystals.展开更多
基金the National Nature Science Foundations of China(12335002,12375078,11975028)H.Q.Zheng and Z.Xiao are also Supported by"the Fundamental Research Funds for the Central Universities"。
文摘Recently,the LHCb experimental group found an exotic state T_(cc)^(+) from the pp→D^(0)D^(0)π^(+)+X process.A key question is whether it is just a molecule or may have a confined tetraquark ingredient.To investigate this,different methods were used,including a two-channel(D^(∗)+D^(0) and D^(∗)0D^(+))K-matrix unitarization and a single-channel Flatté-like parametrization method analyzed utilizing the pole counting rule and spectral density function sum rule.These analyses demonstrated that T_(cc)^(+) is a molecular state,although the possibility that there may exist an elementary ingredient cannot be excluded,according to an approximate analysis of its production rate.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA1400602)the National Natural Science Foundation of China(Grant Nos.12074286,and 12004284)+3 种基金the Shanghai Science and Technology Committee(Grant No.21JC1405600)the Fundamental Research Funds for the Central Universities(Grant No.22120210579)the Chenguang Program of Shanghai Education Development Foundationthe Shanghai Municipal Education Commission(Grant No.21CGA22)。
文摘The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices.In this work,we propose theoretically and realize experimentally unidirectional perfect absorption in a non-Hermitian acoustic system with the help of the topological bound state in the continuum(BIC),which is established by the hybrid interaction between one trivial BIC and another conventional resonant state.In the 2D parameter space spanned by frequency and distance between the two resonators,the topological scattering singularities appear in pairs and are associated with topological distinguished charges.Meanwhile,we reveal the origin of topological charges and their continuous evolution with the loss factor.At a specific loss factor,two topological charges just annihilate together,and acoustic perfect absorption induced by topological BIC is realized at the left incidence,while there is no phase singularity and near-total reflection is observed at the right incidence,hence the system presents extreme asymmetry.Our work bridges the gap between scattering characteristics of non-Hermitian acoustic systems and topological scattering singularities,which may contribute to the research of novel non-Hermitian physics and the practical applications of advanced absorbers and sensors.
文摘By using an approximation for the centrifugal term, we study relativistic bound and scattering states of spin-zero particles in the presence of equal scalar and vector modified Schioberg plus Manning–Rosen potentials for any quantum numbers n and l. Energy eigenvalues and the scattering amplitude are calculated. Some special cases of the problem are also investigated.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61531003,61690195,61701040,and 61427813)the Fund of State Key Laboratory of Information Photonics and Optical Communications,Beijing University of Posts and Telecommunications(BUPT),Chinathe Youth Research and Innovation Program of BUPT,China
文摘The polarization dependences of gain and amplified spontaneous Brillouin scattering(ABS) noise for fiber Brillouin amplifier(FBA) are analyzed through theories, simulations, and experiments.Modified vector propagation equations for calculating the gain of the probe signal and the ABS noise are derived and analyzed in the Stokes spaces.In simulations and experiments, we prove that the gain of the probe signal and the ABS noise are strongly dependent on the relative state of polarization(SOP) of the pump and probe signals.The closer the relative SOP of the pump and probe signals is, the more obvious ABS noise suppression effect will be brought by increasing the power of the input probe signal.
文摘Thermal neutron inelastic scattering experiments have been successfully used tostudy the lattice dynamics of the classical crystalline invar alloys. Y. Endoh et al. havesystematically investigated the temperature dependence of the phonon dispersion forthe Fe-based crystalline invar alloys Fe<sub>65</sub>Ni<sub>35</sub>, Fe<sub>3</sub>Pt and Fe<sub>70</sub>Mn<sub>30</sub> by inelasticneutron scattering, and found that the transverse acoustic-phonon modes become softbelow the magnetic transition temperature. It is suggested that the phonon softeningof these invar alloys may be attributed to the enhancement of
基金supported by the Ministry of Science and Technology of China(Nos.2018YFA0703502 and 2016YFA0200104)the National Natural Science Foundation of China(Nos.51720105003,21790052,52021006,and 21974004)+1 种基金the Strategic Priority Research Program of CAS(No.XDB36030100)the Beijing National Laboratory for Molecular Sciences(No.BNLMSCXTD-202001).
文摘The edges of two-dimensional(2D)materials can exhibit special structure and thus distinctive properties differing from the interior,such as the modified photoluminescence emission,the improved electrocatalytic activity,and the enhanced nonlinear optical response.In this work,we report the observation of abrupt enhancement of Raman scattered light at edges of layered MoS_(2),which is closely related to the polarization of the incident light.More importantly,the intensity of out-of-plane A1g mode is enhanced much more obviously than the in-plane E_(2g)^(1)mode.The unique optical effect at edges is also reflected on the alteration of Raman selection rule.The forbidden Raman modes are observed at edge region,and the polarization of Raman scattered light can be modulated by the edge structure,which differs obviously from that of the interior.We attribute these particular performances to the modulation of the intensity and distribution of the electric field for the incident and Raman scattered light at the edge.This work provides a systematic research on the intensity and polarization modulation of the Raman scattering at edges,which would be helpful for understanding the distinctive optical properties of the edge structure.
基金This work was supported by the Chinese Academy of Sciences, the Ministry of Science and Technology and the National Natural Science Foundation of China.ACKN0WLEDGMENT This work was supported by the Chinese Academy of Sciences, the Ministry of Science and Technology and the National Natural Science Foundation of China.
文摘A crossed molecular beams, state-to-state scattering study was carried out on the F＋H2→HF＋H reaction at the collision energy of 5.02 kJ/mol, using the highly sensitive H atom Rydberg tagging time-of-flight method. All the peaks in the TOF spectra can be clearly assigned to the ro-vibrational structures of the HF product. The forward scattering of the HF product at v′=3 has been observed. The small forward scattering of the HF product at v′=2 has also been detected. Detailed theoretical analysis is required in order to fully understand the dynamical origin of these forward scattering products at this high collision energy.
基金Funded by National Natural Science Foundation of China(No.50572121) Key Pre-research Foundation of Weapon and Equipment(No. 9140A27010206JB35)
文摘In-situ characterization of non-aqueous nano-dispersion systems（NANDS） by freeze-etching transmission electron microscope（FETEM） was reported.To improve just-for-once successive rate of specimen preparation and get good characterization results,an improving specimen preparation method of freezing etching was developed.Size,distribution and morphology of NANDS were directly visualized.Some information of particle dispersion feature and particle density can also be obtained.Reproductivity of the FETEM characterization is excellent.Comparing with laser scattering method,which is liable to give positive error especially for small size particle anchoring disperser,FETEM characterization can give more accurate measurement of particle size.Moreover,FETEM can give dispersion feature of nanoparticle in non-aqueous medium.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51771126 and 11774247)the Youth Foundation of Science and Technology Department of Sichuan Province,China(Grant No.2016JQ0051)the World First-Class University Construction Funding
文摘The evolution of electron correlation and charge density wave （CDW） in 1T-TaS2 single crystal has been investi- gated by temperature-dependent Raman scattering, which undergoes two obvious peaks of Aig modes about 70.8 cm-t and 78.7 cm I at 80 K, respectively. The former peak at 70.8 cm-t is accordant with the lower Hubbard band, resulting in the electron-correlation-driven Mott transition. Strikingly, the latter peak at 78.7 cm-1 shifts toward low energy with increasing the temperature, demonstrating the occurrence of nearly commensurate CDW phase （melted Mott phase）. In this case, phonon transmission could be strongly coupled to commensurate CDW lattice via Coulomb interaction, which likely induces appearance of hexagonal domains suspended in an interdomain phase, composing the melted Mott phase characterized by a shallow electron pocket. Combining electronic structure, atomic structure, transport properties with Ra- man scattering, these findings provide a novel dimension in understanding the relationship between electronic correlation, charge order, and phonon dynamics.
基金Project supported by the National Natural Science Foundation of China （Grant No 10574039） and the Natural Science Foundation of Henan Province, China （Grant No 2006140008 and 2007140015）. Corresponding author.
文摘The comparison between single-point energy scanning （SPES） and geometry optimization （OPT） in determining the equilibrium geometry of the α^3∑u^＋ state for ^7Li2 is made at numerous basis sets such as 6-311＋＋G（2df）, cc-PVTZ, 6-311＋＋G（2df, p）, 6-311G（3df,3pd）, 6-311＋＋G（2df,2pd）, D95（3df,3pd）, 6-311＋＋G, DGDZVP, 6-311＋＋G（3df,2pd）, 6-311G（2df,2pd）, D95V＋＋, CEP-121G, 6-311＋＋G（d,p）, 6-311＋＋G（2df, pd） and 6-311＋＋G（3df,3pd） in full active space using a symmetry-adapted-cluster/ symmetry-adapted-cluster configuration-interaction （SAC/SAC=CI） method presented in Gaussian03 program package. The difference of the equilibrium geometries obtained by SPES and by OPT is reported. Analyses show that the results obtained by SPES are more reasonable than those obtained by OPT. We have calculated the complete potential energy curves at those sets over a wide internuclear distance range from about 3.0α0 to 37.0α0, and the conclusion is that the basis set cc-PVTZ is the most suitable one. With the potential obtained at ccopVTZ, the spectroscopic data （Te, De, D0, ωe,ωeХe, αe and Be） are computed and they are 1.006 eV, 338.71 cm^-1, 307.12 cm^-1, 64.88 cm^-1, 3.41 cm^-1, 0.0187 cm^-1 and 0.279 cm^-1, respectively, which are in good agreement with recent measurements. The total 11 vibrational states are found at J=0. Their corresponding vibrational levels and classical turning points are computed and compared with available RKR data, and good agreement is found. One inertial rotation constant （By） and six centrifugal distortion constants （Dr Hv, Lv, My, Nv, and Ov） are calculated. The scattering length is calculated to be -27.138α0, which is in good accord with the experimental data.
基金financially supported by Pakistan Science foundation(PSF)and Higher Education Commission(HEC) Pakistan
文摘The interactions of non-ionic amphiphilic diblock copolymer poly（oxyethylene/oxybutylene） （E39B18） with anionic surfactant sodium dodecyl sulphate （SDS） and cationic surfactant hexadecyltrimethylammonium bromide （CTAB） were studied by using various techniques such as surface tension, conductivity, steady-state fluorescence and dynamic light scattering. Surface tension measurements were used to determine the critical micelle concentration （CMC） and thereby the free energy of micellization （AGmic）, free energy of adsorption （AG^ds）, surface excess concentration （F） and minimum area per molecule （A）. Conductivity measurements were used to determine the critical micelle concentration （CMC）, critical aggregation concentration （CAC）, polymer saturation point （PSP）, degree of ionization （tr） and counter ion binding （l]）. Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants. The ratio of the first and third vibronic peaks （11/Is） indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions. Aggregation number （N）, number of binding sites （n） and free energy of binding （AGb） for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.
基金supported by the Basic Research Program of China (Grant No. 2011CB921901)the National Natural Science Foundation of China (Grant No. 11074143)
文摘Topological insulators as a new type of quantum matter materials are characterized by a full insulating gap in the bulk and gapless edge/surface states protected by the time-reversal symmetry. We propose that the interference patterns caused by the elastic scattering of defects or impurities are dominated by the surface states at the extremal points on the constant energy contour. Within such a formalism, we summarize our recent theoretical investigations on the elastic scattering of topological surface states by various imperfections, including non-magnetic impurities, magnetic impurities, step edges, and various other defects, in comparison with the recent related experiments in typical topological materials such as BiSb alloys, Bi2Te3, and Bi2Se3 crystals.
