The layered van der Waals(vdW)ferroelectric CuInP2S6(CIPS)exhibits unique cation-hopping-driven phenomena that bring about unconventional properties with intriguing mechanisms and hold promise for advanced application...The layered van der Waals(vdW)ferroelectric CuInP2S6(CIPS)exhibits unique cation-hopping-driven phenomena that bring about unconventional properties with intriguing mechanisms and hold promise for advanced applications in nanoelectronics.However,an explicit analysis of its lattice dynamics and vibrational symmetries,pivotal for understanding the material’s peculiar ferroelectric and ferroionic behaviors,remains incomplete.Here,we employ angle-resolved polarized Raman spectroscopy in concert with first-principles calculations to systematically unravel the anisotropic lattice vibrations of CIPS single crystals.By analyzing the polarization-dependent Raman intensities,we determine the symmetry assignments and Raman tensors of all major vibrational modes,revealing good agreement with theoretical predictions.Furthermore,we demonstrate the utility of Raman spectroscopy as a sensitive and non-invasive probe for structural and ferroelectric order evolution by examining temperature-driven phase transitions and thickness-dependent polarization suppression in CIPS.Our findings establish a foundational framework for correlating lattice dynamics with functional properties in CIPS and provide a methodological blueprint for studying other vdW ferroelectrics.展开更多
Vibrational strong coupling(VSC)provides a promising way towards not only enhanced control of infrared light but also reshaping of molecular properties,which opens up unprecedented opportunities in ultrasensitive infr...Vibrational strong coupling(VSC)provides a promising way towards not only enhanced control of infrared light but also reshaping of molecular properties,which opens up unprecedented opportunities in ultrasensitive infrared spectroscopy,modification of chemical reactions,and exploration of nonlinear quantum effects.Surface plasmon resonance,excited on simple plasmonic resonators in the infrared,has been demonstrated as a means to realize VSC,but suffers from either limited quality factor for realizing large Rabi splitting or poor reconfigurability for precise detuning control.Here we propose and experimentally demonstrate,for the first time,an on-chip plasmonic resonator based on degeneracy breaking of Wood’s anomaly for VSC.Leveraging the low damping rate of the surface state induced by this degeneracy breaking,we achieve a plasmonic resonance with a high-Q factor exceeding~110,resulting in a Rabi splitting up to~112 cm^(-1) with a subwavelength molecular layer.Additionally,the dispersion of the surface state allows for precise control over VSC detuning by simply adjusting the incident angle of excitation light,even in the absence of photons,enabling a broad detuning range up to 300 cm^(-1).These experimental results align well with our analytical model and numerical simulation.This work provides a promising integrated platform for VSC,with various potential applications in on-chip spectroscopy,polariton chemistry,and polariton devices.展开更多
Molecular dynamics(MD)is a powerful method widely used in materials science and solid-state physics.The accuracy of MD simulations depends on the quality of the interatomic potentials.In this work,a special class of e...Molecular dynamics(MD)is a powerful method widely used in materials science and solid-state physics.The accuracy of MD simulations depends on the quality of the interatomic potentials.In this work,a special class of exact solutions to the equations of motion of atoms in a body-centered cubic(bcc)lattice is analyzed.These solutions take the form of delocalized nonlinear vibrational modes(DNVMs)and can serve as an excellent test of the accuracy of the interatomic potentials used in MD modeling for bcc crystals.The accuracy of the potentials can be checked by comparing the frequency response of DNVMs calculated using this or that interatomic potential with that calculated using the more accurate ab initio approach.DNVMs can also be used to train new,more accurate machine learning potentials for bcc metals.To address the above issues,it is important to analyze the properties of DNVMs,which is the main goal of this work.Considering only the point symmetry groups of the bcc lattice,34 DNVMs are found.Since interatomic potentials are not used in finding DNVMs,they are exact solutions for any type of potential.Here,the simplest interatomic potentials with cubic anharmonicity are used to simplify the analysis and to obtain some analytical results.For example,the dispersion relations for small-amplitude phonon modes are derived,taking into account interactions between up to the fourth nearest neighbor.The frequency response of the DNVMs is calculated numerically,and for some DNVMs examples of analytical analysis are given.The energy stored by the interatomic bonds of different lengths is calculated,which is important for testing interatomic potentials.The pros and cons of using DNVMs to test and improve interatomic potentials for metals are discussed.Since DNVMs are the natural vibrational modes of bcc crystals,any reliable interatomic potential must reproduce their properties with reasonable accuracy.展开更多
Ammonium dinitramide(ADN),as a high-energy oxidizer widely applied in the field of rocket and missile propellants,has a prominent issue of high hygroscopicity due to its strong polarity.The previous coating encapsulat...Ammonium dinitramide(ADN),as a high-energy oxidizer widely applied in the field of rocket and missile propellants,has a prominent issue of high hygroscopicity due to its strong polarity.The previous coating encapsulation methods have struggled to address the problems of uneven coating and polarity mismatch.This research innovatively introduces perfluorooctanoic acid(PFOA)as a polar transition intermediate layer.Utilizing the polarity of one end of it to adsorb on the surface of ADN through hydrogen bonds,the problem of polarity mismatch is effectively overcome.Meanwhile,the vibrational magnetron sputtering process has been first applied in the energetic field,with a special vibrating abutment enhancing ADN particle fluidity to solve coating non-uniformity,thus preparing prilled ADN@PFOA@PTFE core-dual-shell composites.Performance tests reveal that this composite material possesses excellent hydrophobic and anti-hygroscopic properties.When left at 25℃and 75%RH for 3 days,moisture absorption was reduced by more than 90%compared to pure ADN.Simultaneously,its thermal stability,heat release performance,and combustion performance have been improved.The research achievements optimize the storage conditions of ADN in the application of rocket and missile propellants,providing solid support and broad development prospects for technological innovation in military fields.展开更多
Cryogenic ion traps offer substantial advantages over their room-temperature counterparts,particularly in terms of stable ion confinement and cooling.However,this technological advancement has introduced a significant...Cryogenic ion traps offer substantial advantages over their room-temperature counterparts,particularly in terms of stable ion confinement and cooling.However,this technological advancement has introduced a significant challenge,namely the generation of additional vibrational noise.This noise is pronounced during the compression and expansion phases of the Gifford–McMahon cycle refrigerator and stems from the mechanical operation of the cold head.The residual vibrational noise can modulate the Rabi oscillation frequency,thereby compromising the fidelity of the quantum logic gate.In this study,we quantitatively assess the impact of residual vibrational noise and introduce an innovative strategy for its mitigation.This strategy was designed to reduce superimposed potential fluctuations within a cryogenic surface electrode ion trap.The measured residual vibrational noise was used for real-time feedback control.Addressing the inverse determination of the compensating potential for a stable superimposed trapping potential is an inherently ill-posed problem considering known measurement noise results.By applying quadratic programming,we numerically calculated the optimal time series for the compensation potential.An ensemble of these compensation voltages was applied in real time to the static compensation electrodes.Although this method is in the theoretical stage,we believe that it can effectively suppress the translation induced by vibrational noise and foster the creation of a stable superimposed harmonic potential.The deployment of this technique is expected to substantially improve the accuracy of quantum operations,thereby fueling the evolution of quantum technologies.展开更多
We present a comprehensive investigation of the vibrational spectra and conformational distribution of neutral and cationic monoethanolamine(MEA)in the gas phase.Using infrared-vacuum ultraviolet non-resonant ionizati...We present a comprehensive investigation of the vibrational spectra and conformational distribution of neutral and cationic monoethanolamine(MEA)in the gas phase.Using infrared-vacuum ultraviolet non-resonant ionization fragmentation detected IR spectroscopy(NRIFD-IR),we obtained vibrational spectra in the 2500-3800 cm^(−1)range for both neutral and cationic MEA.Density functional theory(DFT)calculations at the B3LYPD3(BJ)/def2-TZVPP level were employed to elucidate the molecular structures and vibrational modes.Our analysis revealed twelve distinct conformers for neutral MEA,with N1gʹGgʹbeing the most stable,while cationic MEA exhibited four conformers,among which C1gʹGt conformer was found to be the primary contributor to the observed spectra.The experimental spectra were interpreted through comparison with anharmonic calculations,allowing for detailed assignment of vibrational modes.Notably,we observed significant differences in the OH stretch region between neutral and cationic species,reflecting changes in intramolecular hydrogen bonding upon ionization.Furthermore,our study highlights the necessity for distinct scaling factors when calculating harmonic frequencies for neutral and cationic substances.展开更多
This article presents the optical evaluation of the vibrational behavior of a steel bar,by a non-conventional optoacoustic procedure,the LPD(laser photo deflection)method.On this occasion the bar is located horizontal...This article presents the optical evaluation of the vibrational behavior of a steel bar,by a non-conventional optoacoustic procedure,the LPD(laser photo deflection)method.On this occasion the bar is located horizontal and fixed at both ends.Through our procedure we experimentally find the first 9 Eigen frequencies(21 Hz,60 Hz,116 Hz...)and correlate them using the cantilever theory.展开更多
Curved beams with complex geometries are vital in numerous engineering applications,where precise vibration analysis is crucial for ensuring safe and effective designs.Traditional finite element methods(FEMs) often st...Curved beams with complex geometries are vital in numerous engineering applications,where precise vibration analysis is crucial for ensuring safe and effective designs.Traditional finite element methods(FEMs) often struggle to accurately represent the dynamic characteristics of these structures due to the limitations in their shape function approximations.To overcome this challenge,the current study introduces an innovative finite element(FE)-based technique for the undamped vibrational analysis of curved beams with arbitrary curvature,employing explicitly derived interpolation functions.Initially,the exact interpolation functions are developed for circular are elements with the force method.These functions facilitate the creation of a highly accurate stiffness matrix,which is validated against the benchmark examples.To accommodate arbitrary curvature,a systematic transformation technique is established to approximate the intricate curves with a series of circular arcs.The numerical findings indicate that increasing the number of arc segments enhances accuracy,approaching the exact solutions.The analysis of free vibrations is conducted for both circular and non-circular beams.Mass matrices are derived using two methods:lumped mass and consistent mass,where the latter is based on the interpolation functions.The effectiveness of the proposed method is confirmed through the comparisons with the existing literature,demonstrating strong agreement.Finally,several practical cases involving beams with diverse curvature profiles are analyzed.Both natural frequencies and mode shapes are determined,providing significant insights into the dynamic behavior of these structures.This research offers a dependable and efficient analytical framework for the vibrational analysis of complex curved beams,with promising implications for structural and mechanical engineering.展开更多
Decoupling the complicated vibrational-vibrational （V-V） coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our pre...Decoupling the complicated vibrational-vibrational （V-V） coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our previous work [Acta Phys. Sin. 61 174301 （2012）], an analytical model to predict the sound absorption from vibrational relaxation in a gas medium is proposed. In this paper, we develop the model to decouple the V-V coupled energy to each vibrationaltranslational deexcitation path, and analyze how the multimode relaxations form the peaks of sound absorption spectra in gas mixtures. We prove that a multimode relaxation is the sum of its decoupled single-relaxation processes, and only the decoupled process with a significant isochoric-molar-heat can be observed as an absorption peak. The decoupling model clarifies the essential processes behind the peaks in spectra arising from the multimode relaxations in multi-component gas mixtures. The simulation validates the proposed decoupling model.展开更多
Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identi...Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identification, and time-resolved techniques. In this study, we employ several key technical procedures and successfully develop a highly sensitive femtosecond time-resolved sum frequency generation vibrational spectroscopy （SFG-VS） system. This system is able to measure the spectra with two polarization combinations （ssp and ppp, or psp and ssp） simultaneously. It takes less than several seconds to collect one spectrum. To the best of our knowledge, it is the fastest speed of collecting SFG spectra reported by now. Using the time-resolved measurement, ultrafast vibrational dynamics of the N-H mode of α-helical peptide at water interface is determined. It is found that the membrane environment does not affect the N-H vibrational relaxation dynamics. It is expected that the time-resolved SFG system will play a vital role in the deep understanding of the dynamics and interaction of the complex molecules at surface and interface. Our method may also provide an important technical proposal for the people who plan to develop time-resolved SFG systems with simultaneous measurement of multiple polarization combinations.展开更多
Based on previous laser-induced fluorescence excitation spectroscopy work, the vibrational constants of neutral FeS in the X5 △ electronic state were obtained by directly mapping the ground-state vibrational levels u...Based on previous laser-induced fluorescence excitation spectroscopy work, the vibrational constants of neutral FeS in the X5 △ electronic state were obtained by directly mapping the ground-state vibrational levels up to v＂=3 using conventional laser-induced dispersed fluorescence spectroscopy. The vibrational frequency of FeS（X5 △） （518±5 cm-1） agrees well with that reported in a recent PES measurement （520±30 cm-1） [J. Phys. Chem. A 107, 2821 （2003）] which is the only one prior experimental vibrational frequency value for the 5 △ state of FeS. Careful comparisons of our experimental results and those documented in the literature （mainly from theoretical predictions） suggest that the ground state of FeS is 5 △ state.展开更多
An algebraic Harniltonian for the two coupled nonlinear vibrations of highly excited nonrigid molecule HCP was presented. The Hamiltonian reduces to the conventional one in a limit which was expressed in terms of harm...An algebraic Harniltonian for the two coupled nonlinear vibrations of highly excited nonrigid molecule HCP was presented. The Hamiltonian reduces to the conventional one in a limit which was expressed in terms of harmonic oscillator operators. It showed that the algebraic model can better reproduce the data than the conventional model by fitting the observed data of HCP.展开更多
The potential energy curves of the ground state X2∑＋g of the fluorine molecule have been accurately reconstructed employing the Ryderg-Klein-Rees （RKR） method extrapolated by a Hulburt and Hirschfeler potential fu...The potential energy curves of the ground state X2∑＋g of the fluorine molecule have been accurately reconstructed employing the Ryderg-Klein-Rees （RKR） method extrapolated by a Hulburt and Hirschfeler potential function for longer internuclear distances. Solving the corresponding radial one-dimensional Schr？dinger equation of nuclear motion yields 22 bound vibrational levels above v=0. The comparison of these theoretical levels with the experimental data yields a mean absolute deviation of about 7.6 cm^-1 over the 23 levels. The highest vibrational level energy obtained using this method is 13308.16 cm？1 and the relative deviation compared with the experimental datum of 13408.49 cm^-1 is only 0.74%. The value from our method is much closer and more accurate than the value obtained by the quantum mechanical ab initio method by Bytautas. The reported agreement of the vibrational levels and dissociation energy with experiment is contingent upon the potential energy curve of the F2 ground state.展开更多
In this paper, we have applied the Lie algebraic model to nano-bio molecules to determine the vibrational spectra of different stretching and bending vibrational modes. The determined vibrational energy levels by the ...In this paper, we have applied the Lie algebraic model to nano-bio molecules to determine the vibrational spectra of different stretching and bending vibrational modes. The determined vibrational energy levels by the Lie algebraic model are compared with the experimental data. The results from the theoretical mode[ are consistent with the experimental data. The vibrational energy levels are clustering in the excited states.展开更多
The vibrational wave function of the target theoretically plays an important role in the calculation of vibrational excitation cross sections. By a careful study of the differential cross sections resulting from diffe...The vibrational wave function of the target theoretically plays an important role in the calculation of vibrational excitation cross sections. By a careful study of the differential cross sections resulting from different vibrational wave functions we find that cross sections are susceptible to vibrational wave functions. Minor changes in the vibration wave lhnction may cause a significant change in the cross section. Even more surprising is that by selecting a few numbers of potential models （which determine the vibrational wave functions） we can often calculate the differential scattering cross section in much closer agreement with experiment in the framework of body-frame vibrational close-coupling theory, which suggest that an accurate potential energy may play a more important role in scattering than we thought betbre.展开更多
An improved U（2） algebraic model is introduced to study the stretching and bending vibrational spectra of methane and its isotopomers.The algebraic model with fewer parameters reproduces the experimental spectra wit...An improved U（2） algebraic model is introduced to study the stretching and bending vibrational spectra of methane and its isotopomers.The algebraic model with fewer parameters reproduces the experimental spectra with good precision.Moreover,the obtained parameters describe well the correct behavior of isotopic substitution.It is shown that the Fermi resonance leads to a very fast intramolecular vibrational redistribution among stretches and bends.展开更多
Ba[(Zn_(1-x)Mg_x)_(1/3)Ta(2/3)]O_3(BZMT,x=0,0.2,0.4,0.6,0.8,and 1.0)solid solution ceramics were synthesized by a conventional solid-state sintering technique.Vibration spectra(Raman spectroscopy and Fourier trans for...Ba[(Zn_(1-x)Mg_x)_(1/3)Ta(2/3)]O_3(BZMT,x=0,0.2,0.4,0.6,0.8,and 1.0)solid solution ceramics were synthesized by a conventional solid-state sintering technique.Vibration spectra(Raman spectroscopy and Fourier trans form far-infrared reflection spectroscopy)and X-ray diffraction(XRD)were employed to evaluate the correla tion between microstructures and phonon modes of these solid solutions.Spectroscopic and structural data show sensitivity to structural evolution of samples with Mg^(2+)concentration,and a 1:2 ordered phase appears when x≥0.2.The unit cell parameters decrease with increasing Mg^(2+)content.The ordering degree reaches a relative maximum value in the range of Mg^(2+)content,0.4≤x<0.6.The phonon modes were assigned,and the correlation of phonon vibrations in the microstructure were analyzed.The position and width of the phonon modes were determined and correlated to the ionic radii for the different atoms substituted in the B'-site.展开更多
Cell membranes play a crucial role in many biological functions of cells. A small change in the composition of cell membranes can strongly influence the functions of membrane-associated proteins, such as ion and water...Cell membranes play a crucial role in many biological functions of cells. A small change in the composition of cell membranes can strongly influence the functions of membrane-associated proteins, such as ion and water channels, and thus mediate the chemical and physical balance in cells. Such composition change could originate from the introduction of short-chain alcohols, or other anesthetics into membranes. In this work, we have applied sum frequency generation vibrational spectroscopy （SFG-VS）, supplemented by attenuated total reflectance Fourier transform infrared spectroscopy （ATR-FTIR）, to investigate interaction between methanol and 1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine （d54-DMPC） lipid bilayers. Lipid＇s hydrocarbon interior is deuterated while its head group is hydrogenated. At the same time, CH3 symmetric stretch from methanol and lipid head amine group has different frequency, thus we can distinguish the behaviors of methanol, lipid head amine group, and lipid hydrocarbon interior. Based on the spectral feature of the bending mode of the water molecules replaced by methanol, we determined that the methanol molecules are intercalated into the region between amine and phosphate groups at the lipid hydrophilic head. The dipole of CH3 groups of methanol and lipid head, and the water O-H M1 adopt the same orientation directions. The introduction of methanol into the lipid hydrophilic head group can strongly perturb the entire length of the alkyl chains, resulting that the signals of CD2 and CD3 groups from both leaflets can not cancel each other.展开更多
Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the ...Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the stability of the end rings of the three silica nanotubes gradually decreases with increase in temperature. The validity of the vibrational features of silica nanotubes is shown by the vibrational density of states. Infrared spectra on the silica nanotubes under different temperatures are investigated. A detailed assignment of each spectral peak to the corresponding vibrational mode of the three nanotubes has been addressed. The results are in good agreement with the other theoretical and experimental展开更多
On the basis of the records of strong seismic events taking place in soft carbonate sediments, a new seismic sequence system of vibrational liquefaction is established, which consists of a series of units, such as esc...On the basis of the records of strong seismic events taking place in soft carbonate sediments, a new seismic sequence system of vibrational liquefaction is established, which consists of a series of units, such as escaped structure of micrite veins and liquefied deformation formed in the period of seismic liquefaction, land subsidence structure after liquefaction, tsunamic hummocky and turbidite produced by seismic events, This sequence is a generalization and summation of field observation in vast areas, which shows the whole process of a strong seismic event and provides an unified theoretical explanation. The pattern of the seismic sequence by vibrational liquefaction provides one of correlation standards for geologists in the field to discriminate events in carbonate sequences. Based on the pattern of seismic sequence, the authors first advance a new conception of the Palaeo-Tanlu (Tancheng-Lujiang) Zone and discuss primarily its geological significations.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12474089,12574102 for L.Y.and L.F.,and 12404102 for J.Z.)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions(for L.Y.and L.F.)+2 种基金the Natural Science Foundation of the Jiangsu Province(Grant No.BK20230806 for J.Z.)Southeast University Interdisciplinary Research Program for Young Scholars(Grant No.2024FGC1008 for J.Z.)the support by the State Key Laboratory of Solid State Microstructures(Nanjing University)(No.M37067)。
文摘The layered van der Waals(vdW)ferroelectric CuInP2S6(CIPS)exhibits unique cation-hopping-driven phenomena that bring about unconventional properties with intriguing mechanisms and hold promise for advanced applications in nanoelectronics.However,an explicit analysis of its lattice dynamics and vibrational symmetries,pivotal for understanding the material’s peculiar ferroelectric and ferroionic behaviors,remains incomplete.Here,we employ angle-resolved polarized Raman spectroscopy in concert with first-principles calculations to systematically unravel the anisotropic lattice vibrations of CIPS single crystals.By analyzing the polarization-dependent Raman intensities,we determine the symmetry assignments and Raman tensors of all major vibrational modes,revealing good agreement with theoretical predictions.Furthermore,we demonstrate the utility of Raman spectroscopy as a sensitive and non-invasive probe for structural and ferroelectric order evolution by examining temperature-driven phase transitions and thickness-dependent polarization suppression in CIPS.Our findings establish a foundational framework for correlating lattice dynamics with functional properties in CIPS and provide a methodological blueprint for studying other vdW ferroelectrics.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFE0105200)the National Nature Science Foundation of China(Grant No.62405284)+2 种基金the Key Research and Development Program of Henan Province(Grant No.241111220600)the JSPS KAKENHI(Grant No.JP20K14785)the Murata Science Foundation.
文摘Vibrational strong coupling(VSC)provides a promising way towards not only enhanced control of infrared light but also reshaping of molecular properties,which opens up unprecedented opportunities in ultrasensitive infrared spectroscopy,modification of chemical reactions,and exploration of nonlinear quantum effects.Surface plasmon resonance,excited on simple plasmonic resonators in the infrared,has been demonstrated as a means to realize VSC,but suffers from either limited quality factor for realizing large Rabi splitting or poor reconfigurability for precise detuning control.Here we propose and experimentally demonstrate,for the first time,an on-chip plasmonic resonator based on degeneracy breaking of Wood’s anomaly for VSC.Leveraging the low damping rate of the surface state induced by this degeneracy breaking,we achieve a plasmonic resonance with a high-Q factor exceeding~110,resulting in a Rabi splitting up to~112 cm^(-1) with a subwavelength molecular layer.Additionally,the dispersion of the surface state allows for precise control over VSC detuning by simply adjusting the incident angle of excitation light,even in the absence of photons,enabling a broad detuning range up to 300 cm^(-1).These experimental results align well with our analytical model and numerical simulation.This work provides a promising integrated platform for VSC,with various potential applications in on-chip spectroscopy,polariton chemistry,and polariton devices.
基金support of the RSF Grant No.24-11-00139(analytics,numerical results,manuscript writing)Daxing Xiong acknowledges the support of the NNSF Grant No.12275116,the NSF Grant No.2021J02051,and the startup fund Grant No.MJY21035For Aleksey A.Kudreyko,this work was supported by the Bashkir StateMedicalUniversity StrategicAcademic Leadership Program(PRIORITY-2030)(analytics).
文摘Molecular dynamics(MD)is a powerful method widely used in materials science and solid-state physics.The accuracy of MD simulations depends on the quality of the interatomic potentials.In this work,a special class of exact solutions to the equations of motion of atoms in a body-centered cubic(bcc)lattice is analyzed.These solutions take the form of delocalized nonlinear vibrational modes(DNVMs)and can serve as an excellent test of the accuracy of the interatomic potentials used in MD modeling for bcc crystals.The accuracy of the potentials can be checked by comparing the frequency response of DNVMs calculated using this or that interatomic potential with that calculated using the more accurate ab initio approach.DNVMs can also be used to train new,more accurate machine learning potentials for bcc metals.To address the above issues,it is important to analyze the properties of DNVMs,which is the main goal of this work.Considering only the point symmetry groups of the bcc lattice,34 DNVMs are found.Since interatomic potentials are not used in finding DNVMs,they are exact solutions for any type of potential.Here,the simplest interatomic potentials with cubic anharmonicity are used to simplify the analysis and to obtain some analytical results.For example,the dispersion relations for small-amplitude phonon modes are derived,taking into account interactions between up to the fourth nearest neighbor.The frequency response of the DNVMs is calculated numerically,and for some DNVMs examples of analytical analysis are given.The energy stored by the interatomic bonds of different lengths is calculated,which is important for testing interatomic potentials.The pros and cons of using DNVMs to test and improve interatomic potentials for metals are discussed.Since DNVMs are the natural vibrational modes of bcc crystals,any reliable interatomic potential must reproduce their properties with reasonable accuracy.
基金funded by Open Research Fund Program of National Key Laboratory of Aerospace Chemical Power(NKLACP120241B04)National Natural Science Foundation of China Youth Science Foundation(12402450)。
文摘Ammonium dinitramide(ADN),as a high-energy oxidizer widely applied in the field of rocket and missile propellants,has a prominent issue of high hygroscopicity due to its strong polarity.The previous coating encapsulation methods have struggled to address the problems of uneven coating and polarity mismatch.This research innovatively introduces perfluorooctanoic acid(PFOA)as a polar transition intermediate layer.Utilizing the polarity of one end of it to adsorb on the surface of ADN through hydrogen bonds,the problem of polarity mismatch is effectively overcome.Meanwhile,the vibrational magnetron sputtering process has been first applied in the energetic field,with a special vibrating abutment enhancing ADN particle fluidity to solve coating non-uniformity,thus preparing prilled ADN@PFOA@PTFE core-dual-shell composites.Performance tests reveal that this composite material possesses excellent hydrophobic and anti-hygroscopic properties.When left at 25℃and 75%RH for 3 days,moisture absorption was reduced by more than 90%compared to pure ADN.Simultaneously,its thermal stability,heat release performance,and combustion performance have been improved.The research achievements optimize the storage conditions of ADN in the application of rocket and missile propellants,providing solid support and broad development prospects for technological innovation in military fields.
基金supported by the National Natural Science Foundation of China(Grant Nos.12204543,12004430,12074433,12174447,and 12174448)。
文摘Cryogenic ion traps offer substantial advantages over their room-temperature counterparts,particularly in terms of stable ion confinement and cooling.However,this technological advancement has introduced a significant challenge,namely the generation of additional vibrational noise.This noise is pronounced during the compression and expansion phases of the Gifford–McMahon cycle refrigerator and stems from the mechanical operation of the cold head.The residual vibrational noise can modulate the Rabi oscillation frequency,thereby compromising the fidelity of the quantum logic gate.In this study,we quantitatively assess the impact of residual vibrational noise and introduce an innovative strategy for its mitigation.This strategy was designed to reduce superimposed potential fluctuations within a cryogenic surface electrode ion trap.The measured residual vibrational noise was used for real-time feedback control.Addressing the inverse determination of the compensating potential for a stable superimposed trapping potential is an inherently ill-posed problem considering known measurement noise results.By applying quadratic programming,we numerically calculated the optimal time series for the compensation potential.An ensemble of these compensation voltages was applied in real time to the static compensation electrodes.Although this method is in the theoretical stage,we believe that it can effectively suppress the translation induced by vibrational noise and foster the creation of a stable superimposed harmonic potential.The deployment of this technique is expected to substantially improve the accuracy of quantum operations,thereby fueling the evolution of quantum technologies.
基金the Dalian Coherent Light Source (DCLS) for support and assistancesurported by the National Natural Science Foundation of China (No.22288201)+1 种基金the Chinese Academy of Sciences (GJJSTD20220001)the Innovation Program for Quantum Science and Technology (No.2021ZD0303305)。
文摘We present a comprehensive investigation of the vibrational spectra and conformational distribution of neutral and cationic monoethanolamine(MEA)in the gas phase.Using infrared-vacuum ultraviolet non-resonant ionization fragmentation detected IR spectroscopy(NRIFD-IR),we obtained vibrational spectra in the 2500-3800 cm^(−1)range for both neutral and cationic MEA.Density functional theory(DFT)calculations at the B3LYPD3(BJ)/def2-TZVPP level were employed to elucidate the molecular structures and vibrational modes.Our analysis revealed twelve distinct conformers for neutral MEA,with N1gʹGgʹbeing the most stable,while cationic MEA exhibited four conformers,among which C1gʹGt conformer was found to be the primary contributor to the observed spectra.The experimental spectra were interpreted through comparison with anharmonic calculations,allowing for detailed assignment of vibrational modes.Notably,we observed significant differences in the OH stretch region between neutral and cationic species,reflecting changes in intramolecular hydrogen bonding upon ionization.Furthermore,our study highlights the necessity for distinct scaling factors when calculating harmonic frequencies for neutral and cationic substances.
文摘This article presents the optical evaluation of the vibrational behavior of a steel bar,by a non-conventional optoacoustic procedure,the LPD(laser photo deflection)method.On this occasion the bar is located horizontal and fixed at both ends.Through our procedure we experimentally find the first 9 Eigen frequencies(21 Hz,60 Hz,116 Hz...)and correlate them using the cantilever theory.
文摘Curved beams with complex geometries are vital in numerous engineering applications,where precise vibration analysis is crucial for ensuring safe and effective designs.Traditional finite element methods(FEMs) often struggle to accurately represent the dynamic characteristics of these structures due to the limitations in their shape function approximations.To overcome this challenge,the current study introduces an innovative finite element(FE)-based technique for the undamped vibrational analysis of curved beams with arbitrary curvature,employing explicitly derived interpolation functions.Initially,the exact interpolation functions are developed for circular are elements with the force method.These functions facilitate the creation of a highly accurate stiffness matrix,which is validated against the benchmark examples.To accommodate arbitrary curvature,a systematic transformation technique is established to approximate the intricate curves with a series of circular arcs.The numerical findings indicate that increasing the number of arc segments enhances accuracy,approaching the exact solutions.The analysis of free vibrations is conducted for both circular and non-circular beams.Mass matrices are derived using two methods:lumped mass and consistent mass,where the latter is based on the interpolation functions.The effectiveness of the proposed method is confirmed through the comparisons with the existing literature,demonstrating strong agreement.Finally,several practical cases involving beams with diverse curvature profiles are analyzed.Both natural frequencies and mode shapes are determined,providing significant insights into the dynamic behavior of these structures.This research offers a dependable and efficient analytical framework for the vibrational analysis of complex curved beams,with promising implications for structural and mechanical engineering.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60971009 and 61001011)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090142110019)+1 种基金the Natural Science Foundation of Hubei Province, China (Grant No. 2010CDB02701)the Fundamental Research Funds for the Central Universities, China (Grant No. 2012QN083)
文摘Decoupling the complicated vibrational-vibrational （V-V） coupling of a multimode vibrational relaxation remains a challenge for analyzing the sound relaxational absorption in multi-component gas mixtures. In our previous work [Acta Phys. Sin. 61 174301 （2012）], an analytical model to predict the sound absorption from vibrational relaxation in a gas medium is proposed. In this paper, we develop the model to decouple the V-V coupled energy to each vibrationaltranslational deexcitation path, and analyze how the multimode relaxations form the peaks of sound absorption spectra in gas mixtures. We prove that a multimode relaxation is the sum of its decoupled single-relaxation processes, and only the decoupled process with a significant isochoric-molar-heat can be observed as an absorption peak. The decoupling model clarifies the essential processes behind the peaks in spectra arising from the multimode relaxations in multi-component gas mixtures. The simulation validates the proposed decoupling model.
文摘Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identification, and time-resolved techniques. In this study, we employ several key technical procedures and successfully develop a highly sensitive femtosecond time-resolved sum frequency generation vibrational spectroscopy （SFG-VS） system. This system is able to measure the spectra with two polarization combinations （ssp and ppp, or psp and ssp） simultaneously. It takes less than several seconds to collect one spectrum. To the best of our knowledge, it is the fastest speed of collecting SFG spectra reported by now. Using the time-resolved measurement, ultrafast vibrational dynamics of the N-H mode of α-helical peptide at water interface is determined. It is found that the membrane environment does not affect the N-H vibrational relaxation dynamics. It is expected that the time-resolved SFG system will play a vital role in the deep understanding of the dynamics and interaction of the complex molecules at surface and interface. Our method may also provide an important technical proposal for the people who plan to develop time-resolved SFG systems with simultaneous measurement of multiple polarization combinations.
基金Acknowledgment： This work was supported by the National Natural Science Foundation of China （No.20673107 and No.20873133）, the National Basic Research Program of China （No.2007CB815203 and No.2010CB923302）, the Chinese Academy of Sciences （No.KJCX2-YW-N24）, and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education of China.
文摘Based on previous laser-induced fluorescence excitation spectroscopy work, the vibrational constants of neutral FeS in the X5 △ electronic state were obtained by directly mapping the ground-state vibrational levels up to v＂=3 using conventional laser-induced dispersed fluorescence spectroscopy. The vibrational frequency of FeS（X5 △） （518±5 cm-1） agrees well with that reported in a recent PES measurement （520±30 cm-1） [J. Phys. Chem. A 107, 2821 （2003）] which is the only one prior experimental vibrational frequency value for the 5 △ state of FeS. Careful comparisons of our experimental results and those documented in the literature （mainly from theoretical predictions） suggest that the ground state of FeS is 5 △ state.
文摘An algebraic Harniltonian for the two coupled nonlinear vibrations of highly excited nonrigid molecule HCP was presented. The Hamiltonian reduces to the conventional one in a limit which was expressed in terms of harmonic oscillator operators. It showed that the algebraic model can better reproduce the data than the conventional model by fitting the observed data of HCP.
基金This work was supported by the National Natural Science Foundation of China （No.20273066）.
文摘The potential energy curves of the ground state X2∑＋g of the fluorine molecule have been accurately reconstructed employing the Ryderg-Klein-Rees （RKR） method extrapolated by a Hulburt and Hirschfeler potential function for longer internuclear distances. Solving the corresponding radial one-dimensional Schr？dinger equation of nuclear motion yields 22 bound vibrational levels above v=0. The comparison of these theoretical levels with the experimental data yields a mean absolute deviation of about 7.6 cm^-1 over the 23 levels. The highest vibrational level energy obtained using this method is 13308.16 cm？1 and the relative deviation compared with the experimental datum of 13408.49 cm^-1 is only 0.74%. The value from our method is much closer and more accurate than the value obtained by the quantum mechanical ab initio method by Bytautas. The reported agreement of the vibrational levels and dissociation energy with experiment is contingent upon the potential energy curve of the F2 ground state.
文摘In this paper, we have applied the Lie algebraic model to nano-bio molecules to determine the vibrational spectra of different stretching and bending vibrational modes. The determined vibrational energy levels by the Lie algebraic model are compared with the experimental data. The results from the theoretical mode[ are consistent with the experimental data. The vibrational energy levels are clustering in the excited states.
基金supported by the National Natural Science Foundation of China(Grant No.11647058)the Fund for Sichuan Distinguished Scientists(Grant No.2015JQ0042)the Youth Innovation Team of the Education Department of Sichuan Province,China(Grant No.14TD0013)
文摘The vibrational wave function of the target theoretically plays an important role in the calculation of vibrational excitation cross sections. By a careful study of the differential cross sections resulting from different vibrational wave functions we find that cross sections are susceptible to vibrational wave functions. Minor changes in the vibration wave lhnction may cause a significant change in the cross section. Even more surprising is that by selecting a few numbers of potential models （which determine the vibrational wave functions） we can often calculate the differential scattering cross section in much closer agreement with experiment in the framework of body-frame vibrational close-coupling theory, which suggest that an accurate potential energy may play a more important role in scattering than we thought betbre.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11174099)
文摘An improved U（2） algebraic model is introduced to study the stretching and bending vibrational spectra of methane and its isotopomers.The algebraic model with fewer parameters reproduces the experimental spectra with good precision.Moreover,the obtained parameters describe well the correct behavior of isotopic substitution.It is shown that the Fermi resonance leads to a very fast intramolecular vibrational redistribution among stretches and bends.
文摘Ba[(Zn_(1-x)Mg_x)_(1/3)Ta(2/3)]O_3(BZMT,x=0,0.2,0.4,0.6,0.8,and 1.0)solid solution ceramics were synthesized by a conventional solid-state sintering technique.Vibration spectra(Raman spectroscopy and Fourier trans form far-infrared reflection spectroscopy)and X-ray diffraction(XRD)were employed to evaluate the correla tion between microstructures and phonon modes of these solid solutions.Spectroscopic and structural data show sensitivity to structural evolution of samples with Mg^(2+)concentration,and a 1:2 ordered phase appears when x≥0.2.The unit cell parameters decrease with increasing Mg^(2+)content.The ordering degree reaches a relative maximum value in the range of Mg^(2+)content,0.4≤x<0.6.The phonon modes were assigned,and the correlation of phonon vibrations in the microstructure were analyzed.The position and width of the phonon modes were determined and correlated to the ionic radii for the different atoms substituted in the B'-site.
文摘Cell membranes play a crucial role in many biological functions of cells. A small change in the composition of cell membranes can strongly influence the functions of membrane-associated proteins, such as ion and water channels, and thus mediate the chemical and physical balance in cells. Such composition change could originate from the introduction of short-chain alcohols, or other anesthetics into membranes. In this work, we have applied sum frequency generation vibrational spectroscopy （SFG-VS）, supplemented by attenuated total reflectance Fourier transform infrared spectroscopy （ATR-FTIR）, to investigate interaction between methanol and 1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine （d54-DMPC） lipid bilayers. Lipid＇s hydrocarbon interior is deuterated while its head group is hydrogenated. At the same time, CH3 symmetric stretch from methanol and lipid head amine group has different frequency, thus we can distinguish the behaviors of methanol, lipid head amine group, and lipid hydrocarbon interior. Based on the spectral feature of the bending mode of the water molecules replaced by methanol, we determined that the methanol molecules are intercalated into the region between amine and phosphate groups at the lipid hydrophilic head. The dipole of CH3 groups of methanol and lipid head, and the water O-H M1 adopt the same orientation directions. The introduction of methanol into the lipid hydrophilic head group can strongly perturb the entire length of the alkyl chains, resulting that the signals of CD2 and CD3 groups from both leaflets can not cancel each other.
文摘Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the stability of the end rings of the three silica nanotubes gradually decreases with increase in temperature. The validity of the vibrational features of silica nanotubes is shown by the vibrational density of states. Infrared spectra on the silica nanotubes under different temperatures are investigated. A detailed assignment of each spectral peak to the corresponding vibrational mode of the three nanotubes has been addressed. The results are in good agreement with the other theoretical and experimental
基金A part of the results of the Project cosponsored by the Natural Scienee Fundation of China(49070127)the Chinese Academy of Geological Sciences(B8901)
文摘On the basis of the records of strong seismic events taking place in soft carbonate sediments, a new seismic sequence system of vibrational liquefaction is established, which consists of a series of units, such as escaped structure of micrite veins and liquefied deformation formed in the period of seismic liquefaction, land subsidence structure after liquefaction, tsunamic hummocky and turbidite produced by seismic events, This sequence is a generalization and summation of field observation in vast areas, which shows the whole process of a strong seismic event and provides an unified theoretical explanation. The pattern of the seismic sequence by vibrational liquefaction provides one of correlation standards for geologists in the field to discriminate events in carbonate sequences. Based on the pattern of seismic sequence, the authors first advance a new conception of the Palaeo-Tanlu (Tancheng-Lujiang) Zone and discuss primarily its geological significations.
