When the molecular ions XYZ＋ （XY2＋） are excited simultaneously from an electronic state E0 into two higher electronic states Ea and EZ with supervened dissociation or predisso- ciation, competition between the α ...When the molecular ions XYZ＋ （XY2＋） are excited simultaneously from an electronic state E0 into two higher electronic states Ea and EZ with supervened dissociation or predisso- ciation, competition between the α and β excitation-dissociation channels occurs. A the- oretical model is provided to deal with the competition of the two excitation-dissociation channels with more than two kinds of ionic products for XYZ＋ （XY2＋）. Supposing that the photo-excitation rates of two states Eα and Eβ are much less than their dissociation or pre-dissociation rates, a theoretical equation can be deduced to fit the measured data, which reflects the dependence of the product branching ratios on the intensity ratios of two excitation lasers. From the fitted parameters the excitation cross section ratios are obtained. In experiment, we studied the competition between two excitation-dissociation channels of CO^2＋. By measuring the dependence of the product branching ratio on the intensity ratio of two dissociation lasers and fitting the experiment data with the theoretical equation, excitation cross section ratios were deduced.展开更多
We propose an efficient method for the generation of an isolated attosecond pulse from the asymmetric molecular ions HeH^2＋ by adding a half-cycle-like field （HCLF） to the fundamental driving laser field. The high-...We propose an efficient method for the generation of an isolated attosecond pulse from the asymmetric molecular ions HeH^2＋ by adding a half-cycle-like field （HCLF） to the fundamental driving laser field. The high-order harmonic generation （HHG） is investigated by numerically sowing the time-dependent Schrodinger equation. By performing the time-frequency distributions and the electronic wave packet probability densities, we find that the optimizing combined field is not only useful for extending the HHG cutoff, but also for simplifying the recombination channels through controlling the electron localization. In addition, by adjusting the intensity of the HCLF, a dominant short quantum path is selected to contribute the HHG spectrum. As a result, a 75-as isolated attosecond pulse is obtained by superposing a proper range of the harmonics.展开更多
We theoretically investigate the electron localization around two nuclei in harmonic emission from asymmetric molecular ion. The results show that the ionization process of electron localized around one nucleus compet...We theoretically investigate the electron localization around two nuclei in harmonic emission from asymmetric molecular ion. The results show that the ionization process of electron localized around one nucleus competes with its transfer process to the other nucleus. By increasing the initial vibrational level, more electrons localized around the nucleus D＋ tend to transfer to the nucleus He2＋ so that the ionizations of electrons localized around the nucleus He2＋ increase. In this case, the difference in harmonic efficiency between Hell2＋ and HeD2＋ decreases while the difference in harmonic spectral structure increases. The evident minimum can be observed the spectral structure of HeD2＋, which is due to the strong in the harmonic spectrum of Hell2＋ compared with that in interference of multiple recombination channels originating from two nuclei. Time-dependent nuclear probability density, electron-nuclear probability density, double-well model, and time-frequency maps are presented to explain the underlying mechanisms.展开更多
In this paper, we overview recent advances in high-precision structure calculations of the hydrogen molecular ions （H2＋ and HD＋）, including nonrelativistic energy eigenvalues and relativistic and quantum electrody...In this paper, we overview recent advances in high-precision structure calculations of the hydrogen molecular ions （H2＋ and HD＋）, including nonrelativistic energy eigenvalues and relativistic and quantum electrodynamic corrections. In combination with high-precision measurements, it is feasible to precisely determine a molecular-based value of the proton- to-electron mass ratio. An experimental scheme is presented for measuring the rovibrational transition frequency （v,L） ： （0, 0） → （6,1） in HD＋, which is currently underway at the Wuhan Institute of Physics and Mathematics.展开更多
As an improvement on our previous work [J. Phys. B： At. Mol. Opt. Phys. 45 085101（2012）], an accurate method combining the spheroidal coordinates and B-spline basis is applied to study the ground state 1σg and low...As an improvement on our previous work [J. Phys. B： At. Mol. Opt. Phys. 45 085101（2012）], an accurate method combining the spheroidal coordinates and B-spline basis is applied to study the ground state 1σg and low excited states1σu, 1πg,u, 1δg,u, 2σg of the H＋2in magnetic fields ranging from 10^9Gs（1 Gs = 10^-4T） to 4.414 × 10^13 Gs. Comparing the one-center method used in our previous work, the present method has a higher precision with a shorter computing time.Equilibrium distances of the states of the H＋2in strong magnetic fields were found to be accurate to 3-5 significant digits（s.d.） and the total energies 6-11 s.d., even for some antibonding state, such as 1πg, which is difficult for the one-center method to give reliable results while the field strength is B ≥ 10^13 Gs. For the large disagreement in previous works, such as the equilibrium distances of the 1πg state at B = 10^9 Gs, the present data may be used as a reference. Further, the potential energy curves（PECs） and the electronic probability density distributions（EPDDs） of the bound states 1σg, 1πu, 1δg and antibonding states 1σu, 1πg, 1δu for B = 1, 10, 100, 1000 a.u.（atomic unit） are compared, so that the different influences of the magnetic fields on the chemical bonds of the bound states and antibonding states are discussed in detail.展开更多
The high-order harmonic generation from an asymmetric molecular ion is theoretically investigated based on the Born-Oppenheimer model with two-dimensional electron dynamics.It is shown that the harmonic intensity chan...The high-order harmonic generation from an asymmetric molecular ion is theoretically investigated based on the Born-Oppenheimer model with two-dimensional electron dynamics.It is shown that the harmonic intensity changes periodically in elliptically polarized laser fields.The periodical character is ellipticity-dependent.By establishing the physical image,the periodicity of the harmonic intensity can be ascribed to the contributions of the ground state and the excited state.Furthermore,the electron dynamics from different electronic states can be selected via combining the elliptically polarized laser field with a static electric field.The harmonics dominated either by ground state or excited state are emitted once in an optical cycle in the combined laser field.展开更多
Based on the reaction microscope at the institute of modern physics, the reaction mechanism in molecular ion-atom collisions is investigated experimentally. The features of this system is illustrated by a kinematicall...Based on the reaction microscope at the institute of modern physics, the reaction mechanism in molecular ion-atom collisions is investigated experimentally. The features of this system is illustrated by a kinematically complete experhnent performed for the collision process. Using the so-called list-mode data recording technique and the coincidence measurement, the momentum vector of each fragment from the molecular ion were recorded event by event. The orientation of the molecular axis for H2^＋ dissociation reactions could be determined for each event in the off-line analysis. The measured orientation of the molecular ion is believed the same as the one at the instance of collision under axial recoil approximation. The polar angle resolution of the molecular orientation of ±8° was obtained.展开更多
High-order harmonic generation from one-dimensional （1D） multi-atom molecular ions ill an ultra-short laser field is theoretically- investigated, The dynamics of the electron in a linearly polarized intense laser fi...High-order harmonic generation from one-dimensional （1D） multi-atom molecular ions ill an ultra-short laser field is theoretically- investigated, The dynamics of the electron in a linearly polarized intense laser field is analyzed in terms of 1D Schroedinger equation with the Crank-Nicolson algorithm, The dependence of high-order harmonics on the laser frequeney and the biter-nuclear distance is discussed, It is found that the optimum range of inter-nuclear distance should be changed to get extended harmonic generation for different laser frequency, and the lower frequency laser pulse is favorable to higher order harmonic generation as the inter-nuclear distance increases.展开更多
We theoretically investigate the elliptical high-order harmonic generation from H_(2)^(+)in two-color cross-linearlypolarized laser fields by numerically solving the two-dimensional time-dependent Schr¨odinger eq...We theoretically investigate the elliptical high-order harmonic generation from H_(2)^(+)in two-color cross-linearlypolarized laser fields by numerically solving the two-dimensional time-dependent Schr¨odinger equation.Numerical simulations show that the crossing-angle-dependent harmonic ellipticity exhibits a prominent antisymmetric structure,which tends to disappear as the internuclear distance increases.Furthermore,ground-state electrons experience resonant transitions to the first excited state at larger internuclear distances,where the disruption of symmetric electron motion suppresses the antisymmetric structure.Additionally,a near-circularly-polarized attosecond pulse can be obtained by modulating the crossing angle.展开更多
In this paper, humic acid （HA） was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since hum...In this paper, humic acid （HA） was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.展开更多
The hydrogen ion implantation process in Smart-Cut technology is investigated in the present paper using molecular dynamics（MD） simulations.This work focuses on the effects of the implantation energy,dose of hydroge...The hydrogen ion implantation process in Smart-Cut technology is investigated in the present paper using molecular dynamics（MD） simulations.This work focuses on the effects of the implantation energy,dose of hydrogen ions and implantation temperature on the distribution of hydrogen ions and defect rate induced by ion implantation.Numerical analysis shows that implanted hydrogen ions follow an approximate Gaussian distribution which mainly depends on the implantation energy and is independent of the hydrogen ion dose and implantation temperature.By introducing a new parameter of defect rate,the influence of the processing parameters on defect rate is also quantitatively examined.展开更多
Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compar...Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.展开更多
The ion selectivity of nickel hexacyanoferrate thin film to alkali cations in ESIX (electrochemically switched ion exchange) processes was investigated using molecular dynamics(MD) techniques; water and cation (Na+ an...The ion selectivity of nickel hexacyanoferrate thin film to alkali cations in ESIX (electrochemically switched ion exchange) processes was investigated using molecular dynamics(MD) techniques; water and cation (Na+ and Cs+) intercalation, configuration, and dynamics in reduced nickel hexacyanoferrate structures with different cation combinations were studied and compared with the experimental results. In the simulations, water was represented by an extended simple point-charge(SPC/E) model, and all other atomic interactions were represented by a universal force field(UFF). The potential energies of various cations combination (Cs+ and Na+) in reduced i-NiHCF and 1 mol/L Cs/NaCl mixed solution were obtained. In most cases, the total potential energy of the solid is reduced when water is intercalated into the various reduced NiHCF structures. Combining the solid and the solution simulation results, it is shown that the solid composition of 3Cs+/1Na+ is the stablest structure form (NaCs3Ni4[Fe(CN)6]3) over a range of solution compositions.展开更多
Molecular dynamics simulation was adopted to study the interaction between sulfosalicylic acid and aluminum,lanthanum and yttrium,and adsorption on kaolinite surfaces.A complexation reaction occurs between sulfosalicy...Molecular dynamics simulation was adopted to study the interaction between sulfosalicylic acid and aluminum,lanthanum and yttrium,and adsorption on kaolinite surfaces.A complexation reaction occurs between sulfosalicylic acid and aluminum,with an interaction energy of-10472.05 kJ/mol.O—Al covalent bonds are formed with a peak value of 7.93,while there is only weak adsorption between sulfosalicylic acid and rare earth ions.A hydrogen bonding reaction with 13605.82 kJ/mol energy occurs between sulfosalicylic acid and the surface of kaolinite(100).Thus,sulfosalicylic acid can form a complex with free aluminum ions,and can also be adsorbed on kaolinite by hydrogen bonding with aluminum in kaolinite(100)surfaces.Leaching of ion-adsorbed type rare earth ore was performed with aluminum inhibited,results show that when sulfosalicylic acid dosage increases from 0 to 0.15 wt%,aluminum ion concentration in the leaching solution decreases from 273.23 to 47.19 mg/L.And the effect of leaching pH value on the effect of sulfosalicylic acid on aluminum inhibition was studied,the result shows that,when the leaching pH value is 4.0—5.0,the rare earth leaching rate and the aluminum ion concentration basically remain unchanged.The molecular dynamics simulation results were verified by detection and analysis of XPS and SEM.展开更多
Physical and chemical phenomena of low-energy ion irradiation on solid surfaces have been studied systematically for many years, due to the wide applications in surface modification, ion implantation and thin-film gro...Physical and chemical phenomena of low-energy ion irradiation on solid surfaces have been studied systematically for many years, due to the wide applications in surface modification, ion implantation and thin-film growth. Recently the bombardment of nano-scale materials with low-energy ions gained much attention. Comared to bulk materials, nano-scale materials show different physical and chemical properties. In this article, we employed molecular dynamics simulations to study the damage caused by low-energy ion irradiation on copper nanowires. By simulating the ion bombardment of 5 different incident energies, namely, 1 keV, 2 keV, 3 keV, 4 keV and 5 keV, we found that the sputtering yield of the incident ion is linearly proportional to the energies of incident ions. Low-energy impacts mainly induce surface damage to the nanowires, and only a few bulk defects were observed. Surface vacancies and adatoms accumulated to form defect clusters on the surface, and their distribution are related to the type of crystal plane, e.g. surface vacancies prefer to stay on （100） plane, while adatoms prefer （110） plane. These results reveal that the size effect will influence the interaction between low-energy ion and nanowire.展开更多
The photodetachment of a hetero-nuclear diatomic molecular negative ion is studied by using a two-centre model. An analytic formula is presented for the electron flux distribution of a heteronuclear diatomic molecular...The photodetachment of a hetero-nuclear diatomic molecular negative ion is studied by using a two-centre model. An analytic formula is presented for the electron flux distribution of a heteronuclear diatomic molecular negative ion. Taking HF- as an example, we calculated the electron flux distributions of this ion for various detached electron energies. The results show that the electron flux distributions exhibit oscillatory structures, which are caused by the interference effect between the two nuclei. Besides, the laser light polarization also has a great influence on the electron flux distribution. The oscillation amplitude is the largest when the laser polarization is parallel to the z-axis; when the laser polarization is perpendicular to the z-axis, the oscillation almost vanishes. This study provides a new understanding of the photodetachment of a heteronuclear diatomic molecular negative ion.展开更多
The interaction of MeV H2^+ molecular ions with thin layer graphene and graphite foils was studied by using a highresolution electrostatic analyzer.A large number of fragment protons were observed at zero degree(along...The interaction of MeV H2^+ molecular ions with thin layer graphene and graphite foils was studied by using a highresolution electrostatic analyzer.A large number of fragment protons were observed at zero degree(along the beam direction) when the H2^+ beam was passing through the monolayer graphene foil, which indicates that the electron of the H2^+ molecular ions can be stripped easily even by the monolayer graphene foil.More trailing than leading protons were found in the energy spectrum, which means significant wake effect was observed in the monolayer graphene foil.The ratio of the numbers of trailing protons over leading protons first increased with the thickness for the much thinner graphene foils, and then decreased with the thickness for the much thicker graphite foils, which indicates that the bending effect of the wake field on the trailing proton varied with the foil thickness.展开更多
This paper reports a comparison between the two kinds of damage behavior in silicon implanted with P_2^+ molecular ions and P^+ atomic ions. The dependence of damage enhancement effect of P_2^+ implanted silicon on io...This paper reports a comparison between the two kinds of damage behavior in silicon implanted with P_2^+ molecular ions and P^+ atomic ions. The dependence of damage enhancement effect of P_2^+ implanted silicon on ion doses, energies and target temperatures, and their annealing behavior in subsequent thermal anneal process are investigated systematically. A multiple collision model has been developed to elucidate the mechanism of the damage enhancement effect.展开更多
A new theoretical model of the triatomic molecular wake effect is proposed and applied to molecular ions D^＋3 and HD^＋2 while passing through a solid. The wake effects resulting from the reactions of the two similar...A new theoretical model of the triatomic molecular wake effect is proposed and applied to molecular ions D^＋3 and HD^＋2 while passing through a solid. The wake effects resulting from the reactions of the two similar ions with thin carbon foil are also investigated by using the Coulomb explosion technique. The experimental results are in good agreement with theoretical estimates and the molecular structure of HD^＋2 is determined by using the model.展开更多
Molecular dynamics was used to quantify the role of the size, charge and polarisability of F–, Cl–, Br–, I– and Na+ ions in their distribution in the water/vapour interface system. Our results show that the larger...Molecular dynamics was used to quantify the role of the size, charge and polarisability of F–, Cl–, Br–, I– and Na+ ions in their distribution in the water/vapour interface system. Our results show that the larger polarizable anions I– and Br– is attracted to the surface which is traced back to surface-modified ion hydration, while the F– was repelled from the interface and the Cl– occupied the total volume of the water slab. Moreover, by artificially increasing the ions charge, anions were localized to the center of the water slab. These results demonstrate that the effect of polarizability cannot be neglected in the transport mechanism.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.20673108）.
文摘When the molecular ions XYZ＋ （XY2＋） are excited simultaneously from an electronic state E0 into two higher electronic states Ea and EZ with supervened dissociation or predisso- ciation, competition between the α and β excitation-dissociation channels occurs. A the- oretical model is provided to deal with the competition of the two excitation-dissociation channels with more than two kinds of ionic products for XYZ＋ （XY2＋）. Supposing that the photo-excitation rates of two states Eα and Eβ are much less than their dissociation or pre-dissociation rates, a theoretical equation can be deduced to fit the measured data, which reflects the dependence of the product branching ratios on the intensity ratios of two excitation lasers. From the fitted parameters the excitation cross section ratios are obtained. In experiment, we studied the competition between two excitation-dissociation channels of CO^2＋. By measuring the dependence of the product branching ratio on the intensity ratio of two dissociation lasers and fitting the experiment data with the theoretical equation, excitation cross section ratios were deduced.
基金Supported by the National Natural Science Foundation of China under Grant No 11404204the Key Project of the Ministry of Education of China under Grant No 211025+1 种基金the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20111404120004the Natural Science Foundation for Young Scientists of Shanxi Province under Grant No 2009021005
文摘We propose an efficient method for the generation of an isolated attosecond pulse from the asymmetric molecular ions HeH^2＋ by adding a half-cycle-like field （HCLF） to the fundamental driving laser field. The high-order harmonic generation （HHG） is investigated by numerically sowing the time-dependent Schrodinger equation. By performing the time-frequency distributions and the electronic wave packet probability densities, we find that the optimizing combined field is not only useful for extending the HHG cutoff, but also for simplifying the recombination channels through controlling the electron localization. In addition, by adjusting the intensity of the HCLF, a dominant short quantum path is selected to contribute the HHG spectrum. As a result, a 75-as isolated attosecond pulse is obtained by superposing a proper range of the harmonics.
基金Project supported by the National Natural Science Foundation of China(Grant No.11404204)the Key Project of Chinese Ministry of Education(Grant No.211025)+2 种基金the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20111404120004)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2009021005)the Innovation Project for Postgraduates of Shanxi Province,China(Grant No.20133081)
文摘We theoretically investigate the electron localization around two nuclei in harmonic emission from asymmetric molecular ion. The results show that the ionization process of electron localized around one nucleus competes with its transfer process to the other nucleus. By increasing the initial vibrational level, more electrons localized around the nucleus D＋ tend to transfer to the nucleus He2＋ so that the ionizations of electrons localized around the nucleus He2＋ increase. In this case, the difference in harmonic efficiency between Hell2＋ and HeD2＋ decreases while the difference in harmonic spectral structure increases. The evident minimum can be observed the spectral structure of HeD2＋, which is due to the strong in the harmonic spectrum of Hell2＋ compared with that in interference of multiple recombination channels originating from two nuclei. Time-dependent nuclear probability density, electron-nuclear probability density, double-well model, and time-frequency maps are presented to explain the underlying mechanisms.
基金supported by the National Natural Science Foundation of China(Grants Nos.11474316,11004221,10974224,and 11274348)the"Hundred Talent Program"of Chinese Academy of Sciences+1 种基金supported by NSERC,SHARCnet,ACEnet of Canadathe CAS/SAFEA International Partnership Program for Creative Research Teams
文摘In this paper, we overview recent advances in high-precision structure calculations of the hydrogen molecular ions （H2＋ and HD＋）, including nonrelativistic energy eigenvalues and relativistic and quantum electrodynamic corrections. In combination with high-precision measurements, it is feasible to precisely determine a molecular-based value of the proton- to-electron mass ratio. An experimental scheme is presented for measuring the rovibrational transition frequency （v,L） ： （0, 0） → （6,1） in HD＋, which is currently underway at the Wuhan Institute of Physics and Mathematics.
基金Project supported by the National Natural Science Foundation of China(Grant No.11204389)the Natural Science Foundation Project of Chongqing(Grant Nos.CSTC2012jj A50015 and CSTC2012jj A00012)
文摘As an improvement on our previous work [J. Phys. B： At. Mol. Opt. Phys. 45 085101（2012）], an accurate method combining the spheroidal coordinates and B-spline basis is applied to study the ground state 1σg and low excited states1σu, 1πg,u, 1δg,u, 2σg of the H＋2in magnetic fields ranging from 10^9Gs（1 Gs = 10^-4T） to 4.414 × 10^13 Gs. Comparing the one-center method used in our previous work, the present method has a higher precision with a shorter computing time.Equilibrium distances of the states of the H＋2in strong magnetic fields were found to be accurate to 3-5 significant digits（s.d.） and the total energies 6-11 s.d., even for some antibonding state, such as 1πg, which is difficult for the one-center method to give reliable results while the field strength is B ≥ 10^13 Gs. For the large disagreement in previous works, such as the equilibrium distances of the 1πg state at B = 10^9 Gs, the present data may be used as a reference. Further, the potential energy curves（PECs） and the electronic probability density distributions（EPDDs） of the bound states 1σg, 1πu, 1δg and antibonding states 1σu, 1πg, 1δu for B = 1, 10, 100, 1000 a.u.（atomic unit） are compared, so that the different influences of the magnetic fields on the chemical bonds of the bound states and antibonding states are discussed in detail.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974229,11404204,and 11947002)the Scientific and Technological Innovation Program of Higher Education Institutions in Shanxi,China(Grant No.2021L255)。
文摘The high-order harmonic generation from an asymmetric molecular ion is theoretically investigated based on the Born-Oppenheimer model with two-dimensional electron dynamics.It is shown that the harmonic intensity changes periodically in elliptically polarized laser fields.The periodical character is ellipticity-dependent.By establishing the physical image,the periodicity of the harmonic intensity can be ascribed to the contributions of the ground state and the excited state.Furthermore,the electron dynamics from different electronic states can be selected via combining the elliptically polarized laser field with a static electric field.The harmonics dominated either by ground state or excited state are emitted once in an optical cycle in the combined laser field.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.10434100） and the Knowledge Innovation Project of Chinese Academy of Sciences.
文摘Based on the reaction microscope at the institute of modern physics, the reaction mechanism in molecular ion-atom collisions is investigated experimentally. The features of this system is illustrated by a kinematically complete experhnent performed for the collision process. Using the so-called list-mode data recording technique and the coincidence measurement, the momentum vector of each fragment from the molecular ion were recorded event by event. The orientation of the molecular axis for H2^＋ dissociation reactions could be determined for each event in the off-line analysis. The measured orientation of the molecular ion is believed the same as the one at the instance of collision under axial recoil approximation. The polar angle resolution of the molecular orientation of ±8° was obtained.
基金This work was supported by the Shanghai Priority Academic Discipline, the National Natural Science Foundation of China (No. 10234030 and 10374030)the National Key Project for Basic Research of China (No.1999075204)the Key Project sponsored by Shanghai Science and Technology Committee (No. 036105019and 03DJ14001)the Twilight Project sponsored by Shanghai Education Committee (No. 03SG23)
文摘High-order harmonic generation from one-dimensional （1D） multi-atom molecular ions ill an ultra-short laser field is theoretically- investigated, The dynamics of the electron in a linearly polarized intense laser field is analyzed in terms of 1D Schroedinger equation with the Crank-Nicolson algorithm, The dependence of high-order harmonics on the laser frequeney and the biter-nuclear distance is discussed, It is found that the optimum range of inter-nuclear distance should be changed to get extended harmonic generation for different laser frequency, and the lower frequency laser pulse is favorable to higher order harmonic generation as the inter-nuclear distance increases.
基金supported by the National Natural Science Foundation of China(Grant Nos.11974229,12204291,and 11404204)the Fund from Graduate Students of Shanxi Normal University,China(Grant No.2023XSY044).
文摘We theoretically investigate the elliptical high-order harmonic generation from H_(2)^(+)in two-color cross-linearlypolarized laser fields by numerically solving the two-dimensional time-dependent Schr¨odinger equation.Numerical simulations show that the crossing-angle-dependent harmonic ellipticity exhibits a prominent antisymmetric structure,which tends to disappear as the internuclear distance increases.Furthermore,ground-state electrons experience resonant transitions to the first excited state at larger internuclear distances,where the disruption of symmetric electron motion suppresses the antisymmetric structure.Additionally,a near-circularly-polarized attosecond pulse can be obtained by modulating the crossing angle.
基金support provided by the National Nature Science Fund(No.50778088)China National Funds for Distinguished Young Scientists(No.50825802)Resources Special Subject of National High Technology Research & Development Project(863 project,No.2006AA06Z383),China.
文摘In this paper, humic acid （HA） was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.
基金Project supported by the National Natural Science Foundation of China(No.11372261)the Excellent Young Scientists Supporting Project of Science and Technology Department of Sichuan Province(No.2013JQ0030)+3 种基金the Supporting Project of Department of Education of Sichuan Province(No.2014zd3132)the Opening Project of Key Laboratory of Testing Technology for Manufacturing Process,Southwest University of Science and Technology-Ministry of Education(No.12zxzk02)the Fund of Doctoral Research of Southwest University of Science and Technology(No.12zx7106)the Postgraduate Innovation Fund Project of Southwest University of Science and Technology(No.14ycxjj0121)
文摘The hydrogen ion implantation process in Smart-Cut technology is investigated in the present paper using molecular dynamics（MD） simulations.This work focuses on the effects of the implantation energy,dose of hydrogen ions and implantation temperature on the distribution of hydrogen ions and defect rate induced by ion implantation.Numerical analysis shows that implanted hydrogen ions follow an approximate Gaussian distribution which mainly depends on the implantation energy and is independent of the hydrogen ion dose and implantation temperature.By introducing a new parameter of defect rate,the influence of the processing parameters on defect rate is also quantitatively examined.
基金the National Natural Science Foundation in China(No.20705028)the Foundation of Key Laboratory of Modem Separation Science in Shaanxi Province(No.05JS61).
文摘Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.
基金Project (20006011) supported by the National Natural Science Foundation of China Project (20021017) by the Natural Science Foundation of Shanxi Province Project (2004-24) by the Scholarship Council Foundation of Shanxi Province
文摘The ion selectivity of nickel hexacyanoferrate thin film to alkali cations in ESIX (electrochemically switched ion exchange) processes was investigated using molecular dynamics(MD) techniques; water and cation (Na+ and Cs+) intercalation, configuration, and dynamics in reduced nickel hexacyanoferrate structures with different cation combinations were studied and compared with the experimental results. In the simulations, water was represented by an extended simple point-charge(SPC/E) model, and all other atomic interactions were represented by a universal force field(UFF). The potential energies of various cations combination (Cs+ and Na+) in reduced i-NiHCF and 1 mol/L Cs/NaCl mixed solution were obtained. In most cases, the total potential energy of the solid is reduced when water is intercalated into the various reduced NiHCF structures. Combining the solid and the solution simulation results, it is shown that the solid composition of 3Cs+/1Na+ is the stablest structure form (NaCs3Ni4[Fe(CN)6]3) over a range of solution compositions.
基金Project supported by the National Natural Science Foundation of China,(51674125,51604128)Outstanding Doctoral Dissertation Project Fund of JXUST(YB2016001)
文摘Molecular dynamics simulation was adopted to study the interaction between sulfosalicylic acid and aluminum,lanthanum and yttrium,and adsorption on kaolinite surfaces.A complexation reaction occurs between sulfosalicylic acid and aluminum,with an interaction energy of-10472.05 kJ/mol.O—Al covalent bonds are formed with a peak value of 7.93,while there is only weak adsorption between sulfosalicylic acid and rare earth ions.A hydrogen bonding reaction with 13605.82 kJ/mol energy occurs between sulfosalicylic acid and the surface of kaolinite(100).Thus,sulfosalicylic acid can form a complex with free aluminum ions,and can also be adsorbed on kaolinite by hydrogen bonding with aluminum in kaolinite(100)surfaces.Leaching of ion-adsorbed type rare earth ore was performed with aluminum inhibited,results show that when sulfosalicylic acid dosage increases from 0 to 0.15 wt%,aluminum ion concentration in the leaching solution decreases from 273.23 to 47.19 mg/L.And the effect of leaching pH value on the effect of sulfosalicylic acid on aluminum inhibition was studied,the result shows that,when the leaching pH value is 4.0—5.0,the rare earth leaching rate and the aluminum ion concentration basically remain unchanged.The molecular dynamics simulation results were verified by detection and analysis of XPS and SEM.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10675009)
文摘Physical and chemical phenomena of low-energy ion irradiation on solid surfaces have been studied systematically for many years, due to the wide applications in surface modification, ion implantation and thin-film growth. Recently the bombardment of nano-scale materials with low-energy ions gained much attention. Comared to bulk materials, nano-scale materials show different physical and chemical properties. In this article, we employed molecular dynamics simulations to study the damage caused by low-energy ion irradiation on copper nanowires. By simulating the ion bombardment of 5 different incident energies, namely, 1 keV, 2 keV, 3 keV, 4 keV and 5 keV, we found that the sputtering yield of the incident ion is linearly proportional to the energies of incident ions. Low-energy impacts mainly induce surface damage to the nanowires, and only a few bulk defects were observed. Surface vacancies and adatoms accumulated to form defect clusters on the surface, and their distribution are related to the type of crystal plane, e.g. surface vacancies prefer to stay on （100） plane, while adatoms prefer （110） plane. These results reveal that the size effect will influence the interaction between low-energy ion and nanowire.
基金supported by the National Natural Science Foundation of China (Grant No. 10604045)the University Science and Technology Planning Program of Shandong Province of China (Grant No. J09LA02)
文摘The photodetachment of a hetero-nuclear diatomic molecular negative ion is studied by using a two-centre model. An analytic formula is presented for the electron flux distribution of a heteronuclear diatomic molecular negative ion. Taking HF- as an example, we calculated the electron flux distributions of this ion for various detached electron energies. The results show that the electron flux distributions exhibit oscillatory structures, which are caused by the interference effect between the two nuclei. Besides, the laser light polarization also has a great influence on the electron flux distribution. The oscillation amplitude is the largest when the laser polarization is parallel to the z-axis; when the laser polarization is perpendicular to the z-axis, the oscillation almost vanishes. This study provides a new understanding of the photodetachment of a heteronuclear diatomic molecular negative ion.
基金Project supported by the National Natural Science Foundation of China(Grant No.11575121)the National Magnetic Confinement Fusion Program of China(Grant No.2014GB125004)
文摘The interaction of MeV H2^+ molecular ions with thin layer graphene and graphite foils was studied by using a highresolution electrostatic analyzer.A large number of fragment protons were observed at zero degree(along the beam direction) when the H2^+ beam was passing through the monolayer graphene foil, which indicates that the electron of the H2^+ molecular ions can be stripped easily even by the monolayer graphene foil.More trailing than leading protons were found in the energy spectrum, which means significant wake effect was observed in the monolayer graphene foil.The ratio of the numbers of trailing protons over leading protons first increased with the thickness for the much thinner graphene foils, and then decreased with the thickness for the much thicker graphite foils, which indicates that the bending effect of the wake field on the trailing proton varied with the foil thickness.
文摘This paper reports a comparison between the two kinds of damage behavior in silicon implanted with P_2^+ molecular ions and P^+ atomic ions. The dependence of damage enhancement effect of P_2^+ implanted silicon on ion doses, energies and target temperatures, and their annealing behavior in subsequent thermal anneal process are investigated systematically. A multiple collision model has been developed to elucidate the mechanism of the damage enhancement effect.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10574095 and 10675087)
文摘A new theoretical model of the triatomic molecular wake effect is proposed and applied to molecular ions D^＋3 and HD^＋2 while passing through a solid. The wake effects resulting from the reactions of the two similar ions with thin carbon foil are also investigated by using the Coulomb explosion technique. The experimental results are in good agreement with theoretical estimates and the molecular structure of HD^＋2 is determined by using the model.
文摘Molecular dynamics was used to quantify the role of the size, charge and polarisability of F–, Cl–, Br–, I– and Na+ ions in their distribution in the water/vapour interface system. Our results show that the larger polarizable anions I– and Br– is attracted to the surface which is traced back to surface-modified ion hydration, while the F– was repelled from the interface and the Cl– occupied the total volume of the water slab. Moreover, by artificially increasing the ions charge, anions were localized to the center of the water slab. These results demonstrate that the effect of polarizability cannot be neglected in the transport mechanism.
