The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_(1/2)nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ion...The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_(1/2)nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^(-1)and 44580 cm^(-1),from which auto-ionization spectra of the Eu 4f^76p_(1/2)nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.展开更多
A cold Rydberg gas, with its atoms prepared initially all in the excited state <span style="white-space:nowrap;">|<em>n</em><sub>0</sub>></span> , with <em>n</...A cold Rydberg gas, with its atoms prepared initially all in the excited state <span style="white-space:nowrap;">|<em>n</em><sub>0</sub>></span> , with <em>n</em><sub>0 </sub><span style="white-space:nowrap;">»</span>1, contains an excessive amount of energy, and presumably is to relax by the Penning-type <em>molecular auto-ionization</em> (<em>MAI</em>), in which a portion of excess energy of one atom is given to another near-by atom and ionizing it. Its complementary process, the <em>resonant energy transfer</em> (<em>RET</em>), is discussed, in which the excess energy of one atom is used on another to form a hyper-excited atomic state <span style="white-space:normal;">|</span><em style="white-space:normal;">n</em><sub style="white-space:normal;"><em>a</em></sub><span style="white-space:normal;">></span> with <em>n</em><sub><em>a</em></sub><span style="white-space:nowrap;">»</span><em style="white-space:normal;">n</em><sub style="white-space:normal;">0</sub>. This process is always present, provided certain resonance energy conditions are satisfied. In this report, the <em>n</em><sub>0</sub> and density dependences of the RET rates are studied in detail, employing a simple model: 1) at low densities, the RET is mediated by the dipole-dipole coupling <em>V</em><sub><em>dd</em></sub> and its rates are generally much smaller than that of MAI, especially for small <em>n</em><sub>0</sub>. But 2) as the density increases, our model shows that the rates become of comparable magnitude or even larger than the MAI rates. The<em> V</em><sub><em>dd</em></sub> is no longer adequate. We, then construct a semi-empirical potential to describe the RET process. 3) At high densities, we show that the atomic orbital of <span style="white-space:normal;">|</span><em style="white-space:normal;">n</em><sub style="white-space:normal;"><em>a</em></sub><span style="white-space:normal;">></span> overlaps with that of neighboring atoms, and the electron-electron potential becomes prominent, resulting in much higher rates.展开更多
The time-resolved photoelectron spectrum (TRPES) of RbI molecule is simulated using the time-dependent wave-packet method. Both the normal three-photon ionization process and auto-ionization process are involved in th...The time-resolved photoelectron spectrum (TRPES) of RbI molecule is simulated using the time-dependent wave-packet method. Both the normal three-photon ionization process and auto-ionization process are involved in the simulation. The calculated results show that the change of delay time will influence the shape of the photoelectron spectrum (PES), and the influence is sub- stantially due to the existence of the crossing between excited states and the strong laser field which will change the position of relevant curves.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11174218)
文摘The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_(1/2)nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^(-1)and 44580 cm^(-1),from which auto-ionization spectra of the Eu 4f^76p_(1/2)nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.
文摘A cold Rydberg gas, with its atoms prepared initially all in the excited state <span style="white-space:nowrap;">|<em>n</em><sub>0</sub>></span> , with <em>n</em><sub>0 </sub><span style="white-space:nowrap;">»</span>1, contains an excessive amount of energy, and presumably is to relax by the Penning-type <em>molecular auto-ionization</em> (<em>MAI</em>), in which a portion of excess energy of one atom is given to another near-by atom and ionizing it. Its complementary process, the <em>resonant energy transfer</em> (<em>RET</em>), is discussed, in which the excess energy of one atom is used on another to form a hyper-excited atomic state <span style="white-space:normal;">|</span><em style="white-space:normal;">n</em><sub style="white-space:normal;"><em>a</em></sub><span style="white-space:normal;">></span> with <em>n</em><sub><em>a</em></sub><span style="white-space:nowrap;">»</span><em style="white-space:normal;">n</em><sub style="white-space:normal;">0</sub>. This process is always present, provided certain resonance energy conditions are satisfied. In this report, the <em>n</em><sub>0</sub> and density dependences of the RET rates are studied in detail, employing a simple model: 1) at low densities, the RET is mediated by the dipole-dipole coupling <em>V</em><sub><em>dd</em></sub> and its rates are generally much smaller than that of MAI, especially for small <em>n</em><sub>0</sub>. But 2) as the density increases, our model shows that the rates become of comparable magnitude or even larger than the MAI rates. The<em> V</em><sub><em>dd</em></sub> is no longer adequate. We, then construct a semi-empirical potential to describe the RET process. 3) At high densities, we show that the atomic orbital of <span style="white-space:normal;">|</span><em style="white-space:normal;">n</em><sub style="white-space:normal;"><em>a</em></sub><span style="white-space:normal;">></span> overlaps with that of neighboring atoms, and the electron-electron potential becomes prominent, resulting in much higher rates.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos.10474060 and 10574083) the Natural Science Foundation of Shandong Province of China (Grant No. Y2003A02).
文摘The time-resolved photoelectron spectrum (TRPES) of RbI molecule is simulated using the time-dependent wave-packet method. Both the normal three-photon ionization process and auto-ionization process are involved in the simulation. The calculated results show that the change of delay time will influence the shape of the photoelectron spectrum (PES), and the influence is sub- stantially due to the existence of the crossing between excited states and the strong laser field which will change the position of relevant curves.