文中介绍了一种基于非谐振线圈的磁共振接收前端的设计原理和电路实现,将商用谱仪上的多通道谐振探头改造为非谐振线圈结构,并设计了一款与非谐振线圈匹配的低噪声放大器(Low Noise Amplifier,LNA),不但能够较好地放大非谐振线圈接收的...文中介绍了一种基于非谐振线圈的磁共振接收前端的设计原理和电路实现,将商用谱仪上的多通道谐振探头改造为非谐振线圈结构,并设计了一款与非谐振线圈匹配的低噪声放大器(Low Noise Amplifier,LNA),不但能够较好地放大非谐振线圈接收的信号,还可以与后级的商用谱仪系统匹配使用,将信号传输到控制台进行数字化处理。在商用300MHz Bruker AVANCE III谱仪上,通过接收前端成功探测到了重水样品的NMR(Nuclear Magnetic Resonance)信号,与谐振电路相比,文中接收前端具有无需重新调谐的优势,实验结果初步验证了该接收前端宽频探测的可行性。展开更多
Based on the vibrational potential curves coupled with the minimum energy reaction path, the partial potential energy surface of the reaction I＋HI→IH＋I was constructed at the QCISD（T）//MP4SDQ level with pseudo po...Based on the vibrational potential curves coupled with the minimum energy reaction path, the partial potential energy surface of the reaction I＋HI→IH＋I was constructed at the QCISD（T）//MP4SDQ level with pseudo potential method. And the formation mechanism of the scattering resonance states of this reaction was well interpreted with the partial potential energy surface. The scattering resonance states of this reaction should belong to Feshbach resonance because of the coupling of the vibrational mode and the translational mode. With the one-dimensional square potential well model, the resonance width and lifetime of the I＋HI（v=0）→IH（v＇=0）＋I state-to-state reaction were calculated, which preferably explained the high-resolved threshold photodetachment spectroscopy of the IHI- anion performed by Neumark et al..展开更多
Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method.To be specific,precise energy ...Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method.To be specific,precise energy eigenvalues of bound 1sns(~1S^e)(n=1-6)states and the resonance parameters i.e.positions and widths of^lS^e states due to 2sns(n=2-5)and 2pnp(n=2-5)configurations of confined helium below N=2 ionization threshold of He^+have been estimated.The two-parameter(Depth and Width)finite oscillator potential is used to represent the confining potential due to the quantum dot.It has been explicitly demonstrated that the electronic structural properties become sensitive functions of the dot size.It is observed from the calculations of ionization potential that the stability of an impurity ion within a quantum dot may be manipulated by varying the confinement parameters.A possibility of controlling the autoionization lifetime of doubly excited states of two-electron ions by tuning the width of the quantum cavity is also discussed here.展开更多
The even-parity autoionizing resonance series 4p^5np＇ [3/2] 1,2, [ 1/2] 1, and 4p^2nf＇ [5/213 of krytpon have been investigated by laser excitation from the two metastable states 4p55s [3/2]2 and 4p^55s＇ [1/2]0 in ...The even-parity autoionizing resonance series 4p^5np＇ [3/2] 1,2, [ 1/2] 1, and 4p^2nf＇ [5/213 of krytpon have been investigated by laser excitation from the two metastable states 4p55s [3/2]2 and 4p^55s＇ [1/2]0 in the photon energy region of 2900（P40000 cm^-1 at experimental bandwidth of -0.1 cm-1. The excitation spectra of the even-parity autoionizing resonance series, most of which are experimentally studied for the first time in this work, show typical asymmetric line shapes. Complementary information on level energies, quantum defects, line profile indices and resonance widths, resonance lifetimes and reduced widths of the auto- ionizing resonances are derived by Fano-type line-shape analyses of the experimental results. Results from this work indicate that the line profile index （q） and the resonance width （F） are approximately proportional to the effective principal quantum number （n＊）; the line separation of the 4p^5np＇ autoionizing resonances is also in good agreement with theoretical model展开更多
The structure and decay properties of d＊ have been detailedly investigated in both the chiral SU（3） quark model and the extended chiral SU（3） quark model that describe the energies of baryon ground states and the...The structure and decay properties of d＊ have been detailedly investigated in both the chiral SU（3） quark model and the extended chiral SU（3） quark model that describe the energies of baryon ground states and the nucleon-nucleon （NN） scattering data satisfactorily. By performing a dynamical coupled-channels study of the system of △△ and hidden-color channel （CC） with quantum numbers l（JP） = 0（3^＋） in the framework of the resonating group method （RGM）, we find that the d＊ has a mass of about 2.38-2.42 GeV and a root-mean-square radius （RMS） of about 0.76-0.88 fm. The channel wave function is extracted by a projection of the RGM wave function onto the physical basis, and the fraction of CC component in the d＊ is found to be about 66%-68%, which indicates that the d＊ is a hexaquark-dominated exotic state. Based on this scenario the partial decay widths of d＊ → dπ^0π^0 and d＊ → dn^＋n^- are further explicitly evaluated and the total width is then obtained by use of the branching ratios extracted from the measured cross sections of other possible decay channels. Both the mass and the decay width of d＊ calculated in this work are compatible with the data （M ≈ 2380 MeV, F ≈ 70 MeV） reported by WASA-at-COSY Collaboration.展开更多
文摘文中介绍了一种基于非谐振线圈的磁共振接收前端的设计原理和电路实现,将商用谱仪上的多通道谐振探头改造为非谐振线圈结构,并设计了一款与非谐振线圈匹配的低噪声放大器(Low Noise Amplifier,LNA),不但能够较好地放大非谐振线圈接收的信号,还可以与后级的商用谱仪系统匹配使用,将信号传输到控制台进行数字化处理。在商用300MHz Bruker AVANCE III谱仪上,通过接收前端成功探测到了重水样品的NMR(Nuclear Magnetic Resonance)信号,与谐振电路相比,文中接收前端具有无需重新调谐的优势,实验结果初步验证了该接收前端宽频探测的可行性。
基金Ⅴ. ACKN0WLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20573064） and Ph.D. Special Research Foundation of Chinese Education Department.
文摘Based on the vibrational potential curves coupled with the minimum energy reaction path, the partial potential energy surface of the reaction I＋HI→IH＋I was constructed at the QCISD（T）//MP4SDQ level with pseudo potential method. And the formation mechanism of the scattering resonance states of this reaction was well interpreted with the partial potential energy surface. The scattering resonance states of this reaction should belong to Feshbach resonance because of the coupling of the vibrational mode and the translational mode. With the one-dimensional square potential well model, the resonance width and lifetime of the I＋HI（v=0）→IH（v＇=0）＋I state-to-state reaction were calculated, which preferably explained the high-resolved threshold photodetachment spectroscopy of the IHI- anion performed by Neumark et al..
基金Financial Support under Grant No.37(3)/14/27/2014-BRNS from the Department of Atomic Energy,BRNS,Government of IndiaFinancial Support under Grant No.PSW-160/14-15(ERO)from University Grants Commission,Government of India
文摘Bound and resonance states of helium atom have been investigated inside a quantum dot by using explicitly correlated Hylleraas type basis set within the framework of stabilization method.To be specific,precise energy eigenvalues of bound 1sns(~1S^e)(n=1-6)states and the resonance parameters i.e.positions and widths of^lS^e states due to 2sns(n=2-5)and 2pnp(n=2-5)configurations of confined helium below N=2 ionization threshold of He^+have been estimated.The two-parameter(Depth and Width)finite oscillator potential is used to represent the confining potential due to the quantum dot.It has been explicitly demonstrated that the electronic structural properties become sensitive functions of the dot size.It is observed from the calculations of ionization potential that the stability of an impurity ion within a quantum dot may be manipulated by varying the confinement parameters.A possibility of controlling the autoionization lifetime of doubly excited states of two-electron ions by tuning the width of the quantum cavity is also discussed here.
基金financially supported by the National Natural Science Foundation of China(51007092)
文摘The even-parity autoionizing resonance series 4p^5np＇ [3/2] 1,2, [ 1/2] 1, and 4p^2nf＇ [5/213 of krytpon have been investigated by laser excitation from the two metastable states 4p55s [3/2]2 and 4p^55s＇ [1/2]0 in the photon energy region of 2900（P40000 cm^-1 at experimental bandwidth of -0.1 cm-1. The excitation spectra of the even-parity autoionizing resonance series, most of which are experimentally studied for the first time in this work, show typical asymmetric line shapes. Complementary information on level energies, quantum defects, line profile indices and resonance widths, resonance lifetimes and reduced widths of the auto- ionizing resonances are derived by Fano-type line-shape analyses of the experimental results. Results from this work indicate that the line profile index （q） and the resonance width （F） are approximately proportional to the effective principal quantum number （n＊）; the line separation of the 4p^5np＇ autoionizing resonances is also in good agreement with theoretical model
基金the National Natural Science Foundation of China(Grant Nos.1147518111475192+2 种基金11035006 and 11165005)the fund provided to the Sino-German CRC 110"Symmetries and the Emergence of Structure in QCD"project by the DFGthe IHEP InnovationFund(Grant No.Y4545190Y2)
文摘The structure and decay properties of d＊ have been detailedly investigated in both the chiral SU（3） quark model and the extended chiral SU（3） quark model that describe the energies of baryon ground states and the nucleon-nucleon （NN） scattering data satisfactorily. By performing a dynamical coupled-channels study of the system of △△ and hidden-color channel （CC） with quantum numbers l（JP） = 0（3^＋） in the framework of the resonating group method （RGM）, we find that the d＊ has a mass of about 2.38-2.42 GeV and a root-mean-square radius （RMS） of about 0.76-0.88 fm. The channel wave function is extracted by a projection of the RGM wave function onto the physical basis, and the fraction of CC component in the d＊ is found to be about 66%-68%, which indicates that the d＊ is a hexaquark-dominated exotic state. Based on this scenario the partial decay widths of d＊ → dπ^0π^0 and d＊ → dn^＋n^- are further explicitly evaluated and the total width is then obtained by use of the branching ratios extracted from the measured cross sections of other possible decay channels. Both the mass and the decay width of d＊ calculated in this work are compatible with the data （M ≈ 2380 MeV, F ≈ 70 MeV） reported by WASA-at-COSY Collaboration.
