The electron momentum spectroscopy of the inner valence orbitals 3a 1 and 2b 2 of methylene fluoride was studied by electron momentum spectroscopy(EMS). The experiment was performed using a high resolution(ΔE=1.15 eV...The electron momentum spectroscopy of the inner valence orbitals 3a 1 and 2b 2 of methylene fluoride was studied by electron momentum spectroscopy(EMS). The experiment was performed using a high resolution(ΔE=1.15 eV FWHM, Δp=0.1 a.u.)(e,2e) EMS spectrometer. The experimental momentum profiles of these two orbitals are compared with those calculated by Hartree-Fork method and Density Functional Theory.展开更多
We report the first measurements of the momentum profiles of highest occupied molecular orbital （HOMO） and the complete valence shell binding energy spectra of cyclopentanone with impact energies of 600 and 1200 eV ...We report the first measurements of the momentum profiles of highest occupied molecular orbital （HOMO） and the complete valence shell binding energy spectra of cyclopentanone with impact energies of 600 and 1200 eV by a binary （e, 2e） spectrometer. The experimental momentum profiles of the HOMO orbital are compared with the theoretical momentum distribution calculated using the Hartree Fock and density functional theory methods with various basis sets. However, none of these calculations gives a completely satisfactory description of the momentum distributions of the HOMO 762. The inadequacy of the calculations could result in the intensity difference of the second maximum at p-1.2a.u. between the experiment and the theory. The discrepancy between experimental and theoretical data in the low-momentum region is explained with the distorted wave effect.展开更多
The binding energy spectrum of all valence orbitals and the momentum distributions of highest occupied molecular orbital （HOMO： 8ag）, 7bu＋7ag, 4bu, 2bg ＋4ag and 2au in 1, 4-dioxane are investigated by electron mo...The binding energy spectrum of all valence orbitals and the momentum distributions of highest occupied molecular orbital （HOMO： 8ag）, 7bu＋7ag, 4bu, 2bg ＋4ag and 2au in 1, 4-dioxane are investigated by electron momentum spectroscopy （EMS） with 600 eV impact energy. The experimental results are consistent with theoretical calcula- tions of C2h chair conformation using the Hartree-Fock method and density functional theory with 6-311＋＋G^＊＊ and AUG-CC-PVTZ basis sets.展开更多
The first electronic structural study of the complete valence shell binding energy spectra of the antimicrobial agent diacetyl, encompassing both the outer and inner valence regions, is reported. The binding energy sp...The first electronic structural study of the complete valence shell binding energy spectra of the antimicrobial agent diacetyl, encompassing both the outer and inner valence regions, is reported. The binding energy spectra as well as the individual orbital momentum profiles have been measured by using a high resolution （e, 2e） electron momentum spectrometer （EMS） at an impact energy of 1200eV plus the binding energy, and using symmetric noncoplanar kinematics. The experimental orbital electron momentum profiles are compared with self-consistent field （SCF） theoretical profiles calculated using the Hartree-Fock approximation and Density Functional theory predictions in the target Kohn-Sham approximation which includes some treatment of correlation via the exchange and correlation potentials with a range of basis sets. The pole strengths of the main ionization peaks from the inner valence orbitals are estimated.展开更多
Dynamic nature of hydrogen bond (H-bond) is central in molecular science of substance transportation, energy transfer, and phase transition in H-bonding networks diversely expressed as solution, crystal, and interfaci...Dynamic nature of hydrogen bond (H-bond) is central in molecular science of substance transportation, energy transfer, and phase transition in H-bonding networks diversely expressed as solution, crystal, and interfacial systems, thus attracting the state-of-the-art revealing of its phenomenological edges and sophisticated causes. However, the current understanding of the ground-state fluctuation from zero-point vibration (ZPV) lacks a firm quasi-classical base, concerning three basic dimensions as geometry, electronic structure, and interaction energy. Here, based on the ab initio molecular dynamics simulation of a ground-state water dimer, temporally separated fluctuation features in the elementary H-bond as the long-time weakening and the minor short-time strengthening are respectively assigned to two low-frequency intermolecular ZPV modes and two O–H stretching ones. Geometrically, the former modes instantaneously lengthen H-bond up to 0.2 Å whose time-averaged effect coverages to about 0.03 Å over 1-picosecond. Electronic-structure fluctuation crosses criteria' borders, dividing into partially covalent and noncovalent H-bonding established for equilibrium models, with a 370% amplitude and the district trend in interaction energy fluctuation compared with conventional dragging models using frozen monomers. Extended physical picture within the normal-mode disclosure further approaches to the dynamic nature of H-bond and better supports the upper-building explorations towards ultrafast and mode-specific manipulation.展开更多
Electronic states of CF2Cl2 （dichlorodifluoromethane, Freon 12） have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. Th...Electronic states of CF2Cl2 （dichlorodifluoromethane, Freon 12） have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. The experimental electron momentum profiles are compared with the density functional theory （DFT） and Hartree-Fock （HF） calculations. The relationship between orbital assignments in different coordinate systems is discussed. A new method of difference analysis based on the new type of electron momentum spectrometer is used to clarify the ambiguities regarding the orbital ordering.展开更多
Imaging the charge distributions and structures of molecules and clusters will promote the understanding of the dynamics of the quantum system.Here,we report a method by using an Ar atom as a tip to probe the charge d...Imaging the charge distributions and structures of molecules and clusters will promote the understanding of the dynamics of the quantum system.Here,we report a method by using an Ar atom as a tip to probe the charge distributions of benzene(Bz)cations in gas phase.Remarkably,the measured charge distributions of Bz^(+)(δ_(H)=0.204,δ_(C)=-0.037)and Bz^(2+)(δ_(H)=0.248,δ_(C)=0.0853)agree well with the calculated Mulliken distributions,and the structures of Bz2 is reconstructed by using the measured charge distributions.The structures of two Bz2isomers(T-shaped and PD isomers)can be resolved from the measured inter-molecular potential V(R)between two Bz ions,and the structures of Bz dimer agree well with the theoretical predictions.展开更多
文摘The electron momentum spectroscopy of the inner valence orbitals 3a 1 and 2b 2 of methylene fluoride was studied by electron momentum spectroscopy(EMS). The experiment was performed using a high resolution(ΔE=1.15 eV FWHM, Δp=0.1 a.u.)(e,2e) EMS spectrometer. The experimental momentum profiles of these two orbitals are compared with those calculated by Hartree-Fork method and Density Functional Theory.
基金Supported by the National Natural Science Foundation of China under Grant No 10575062, and the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20050003084.
文摘We report the first measurements of the momentum profiles of highest occupied molecular orbital （HOMO） and the complete valence shell binding energy spectra of cyclopentanone with impact energies of 600 and 1200 eV by a binary （e, 2e） spectrometer. The experimental momentum profiles of the HOMO orbital are compared with the theoretical momentum distribution calculated using the Hartree Fock and density functional theory methods with various basis sets. However, none of these calculations gives a completely satisfactory description of the momentum distributions of the HOMO 762. The inadequacy of the calculations could result in the intensity difference of the second maximum at p-1.2a.u. between the experiment and the theory. The discrepancy between experimental and theoretical data in the low-momentum region is explained with the distorted wave effect.
基金Supported bv the National Natural Science Foundation of China under Grant No 10575062, and the Specialized Research Fund for the Doctoral Programme of Higher Education under Grant No 20050003084.
文摘The binding energy spectrum of all valence orbitals and the momentum distributions of highest occupied molecular orbital （HOMO： 8ag）, 7bu＋7ag, 4bu, 2bg ＋4ag and 2au in 1, 4-dioxane are investigated by electron momentum spectroscopy （EMS） with 600 eV impact energy. The experimental results are consistent with theoretical calcula- tions of C2h chair conformation using the Hartree-Fock method and density functional theory with 6-311＋＋G^＊＊ and AUG-CC-PVTZ basis sets.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 19854002, 19774037 and 10274040） and the Research Fund for the Doctoral Program Foundation of Institution of Higher Education of China （Grant No 1999000327）.
文摘The first electronic structural study of the complete valence shell binding energy spectra of the antimicrobial agent diacetyl, encompassing both the outer and inner valence regions, is reported. The binding energy spectra as well as the individual orbital momentum profiles have been measured by using a high resolution （e, 2e） electron momentum spectrometer （EMS） at an impact energy of 1200eV plus the binding energy, and using symmetric noncoplanar kinematics. The experimental orbital electron momentum profiles are compared with self-consistent field （SCF） theoretical profiles calculated using the Hartree-Fock approximation and Density Functional theory predictions in the target Kohn-Sham approximation which includes some treatment of correlation via the exchange and correlation potentials with a range of basis sets. The pole strengths of the main ionization peaks from the inner valence orbitals are estimated.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11974136 and 11674123)。
文摘Dynamic nature of hydrogen bond (H-bond) is central in molecular science of substance transportation, energy transfer, and phase transition in H-bonding networks diversely expressed as solution, crystal, and interfacial systems, thus attracting the state-of-the-art revealing of its phenomenological edges and sophisticated causes. However, the current understanding of the ground-state fluctuation from zero-point vibration (ZPV) lacks a firm quasi-classical base, concerning three basic dimensions as geometry, electronic structure, and interaction energy. Here, based on the ab initio molecular dynamics simulation of a ground-state water dimer, temporally separated fluctuation features in the elementary H-bond as the long-time weakening and the minor short-time strengthening are respectively assigned to two low-frequency intermolecular ZPV modes and two O–H stretching ones. Geometrically, the former modes instantaneously lengthen H-bond up to 0.2 Å whose time-averaged effect coverages to about 0.03 Å over 1-picosecond. Electronic-structure fluctuation crosses criteria' borders, dividing into partially covalent and noncovalent H-bonding established for equilibrium models, with a 370% amplitude and the district trend in interaction energy fluctuation compared with conventional dragging models using frozen monomers. Extended physical picture within the normal-mode disclosure further approaches to the dynamic nature of H-bond and better supports the upper-building explorations towards ultrafast and mode-specific manipulation.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 19854002, 19774037 and 10274040） and the Research Fund for the Doctorate Program of Higher Education （Grant No 1999000327）.
文摘Electronic states of CF2Cl2 （dichlorodifluoromethane, Freon 12） have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. The experimental electron momentum profiles are compared with the density functional theory （DFT） and Hartree-Fock （HF） calculations. The relationship between orbital assignments in different coordinate systems is discussed. A new method of difference analysis based on the new type of electron momentum spectrometer is used to clarify the ambiguities regarding the orbital ordering.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0307700)the National Natural Science Foundation of China(Grant Nos.12074143,11974272,11774281,and 12134005)the Science Challenge Project(Grant No.TZ2018005)。
文摘Imaging the charge distributions and structures of molecules and clusters will promote the understanding of the dynamics of the quantum system.Here,we report a method by using an Ar atom as a tip to probe the charge distributions of benzene(Bz)cations in gas phase.Remarkably,the measured charge distributions of Bz^(+)(δ_(H)=0.204,δ_(C)=-0.037)and Bz^(2+)(δ_(H)=0.248,δ_(C)=0.0853)agree well with the calculated Mulliken distributions,and the structures of Bz2 is reconstructed by using the measured charge distributions.The structures of two Bz2isomers(T-shaped and PD isomers)can be resolved from the measured inter-molecular potential V(R)between two Bz ions,and the structures of Bz dimer agree well with the theoretical predictions.
