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ionization cross sections for electron scattering from metastable rare-gas atoms （Ne~＊ and Ar~＊）

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Chinese Physics B 2013年第7期22卷 159-162页

作者：张永志周雅君 Center for Theoretical Atomic and Molecular Physics Academy of Fundamental and Interdisciplinary SciencesHarbin Institute of Technology Academy of Physical Science and Technology Heilongjiang University

The optical-model approach has been used to investigate the electron-impact ionization of metastable rare-gas atoms. A complex equivalent-local polarization potential is obtained to describe the ionization continuum channels. We have calculated the cross sections for collisional ionization of the metastable atoms Ne＊ and Ar＊ by electrons in the energy range from threshold to 200 eV. The present results are in agreement with the available experimental measurements and other theoretical calculations.

关键词： electron scattering metastable rare-gas atom ionization

ionization properties in the collision of Rydberg Cs atoms with CCl_4 molecules

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Science China Mathematics 1998年第7期41卷 779-784页

作者：龚顺生刘炳模王嘉珉顾思洪戴作跃李白文 Wuhan Institute of Physics & Mathematics Chinese Academy of Sciences Wuhan China

The experimental study of ionization in the collision of Rydberg Cs atoms with CCl 4 molecules is conducted using the crossed atomic and molecular beam apparatus. It is found that the relative collision rate constants are not consistent with the prediction of the essentially free electron model in the range of n =30-50. The possible reason for this discrepancy is discussed.

关键词： ionization Rydberg atoms.

ionization and Fragmentation of Butanone Clusters Irradiated by Photons at 355 and 118 nm

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Chemical Research in Chinese Universities 2011年第3期27卷 508-511页

作者： SUN Chang-kai HU Zhan YANG Xue JIN Ming-xing HU Wen-cheng DING Da-jun Institute of Atomic and Molecular Physics Jilin University Changchun 130012 P. R. China

Time-of-flight（TOF） mass spectra of molecular butanone clusters were measured under the irradiation of photons at 355 and 118 nm. Butanone molecular parent ion and several series of butanone cluster fragments such as （CH3COC2H5）nH＋, （CH3COC2H5）nC2H5＋, （CH3COC2H5）nCH3CO＋ and （CH3COC2H5）nC2H5CO＋ were observed. Odd-even variation pattern in the intensity of （CH3COC2H5）nCH3CO＋ is obvious from n=4 to 8. A connection is es-tablished between the fragment clusters （CH3COC2H5）nCH3CO＋ and the neutral clusters （CH3COC2H5）n＋1 based on the consideration of butanone cluster dissociation mainly by losing a radical C2H5？. The stability variation of the neutral clusters calculated via the HF-B3LYP method based on DFT is in agreement with the observed phenomena experimentally, indicating （CH3COC2H5）n＋1（n＋1=5,7） with a ring structure are with higher stability over the adjacent even-number clusters.

关键词： Cluster ionization Fragment Butanone

ionization and Dissociation of Nitrosyl Chloride Molecule in the Intense Femtosecond Laser Field

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Chinese Journal of Chemistry 2006年第7期24卷 867-871页

作者：姚立葛茂发王殿勋吴成印徐楠龚旗煌 Beijing National Laboratory for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China State Key Laboratory for Mesoscopic Physics Department of Physics Peking University Beijing 100871 China

ionization and dissociation of nitrosyl chloride CINO were studied using femtosecond laser mass spectra technique. Strong fragmental ions NO^＋ and Cl^＋ were observed with the laser intensity varied from 3.2× 10^14 to 2.5×10^15 W/cm^2. These fragmental ions were attributed to the direct dissociation of the parent ions. Electronic structure calculations were also carried out with Hartree-Fock, density functional and correlated levels of theory to understand the possible fragmentation pathways. The very low N-Cl bond energy in the parent ion of nitrosyl chloride is a clear reason for the absence of CINO^＋ and CIN^＋ ion peaks from the femtosecond laser mass spectrum.

关键词： nitrosyl chloride intense femtosecond laser field electronic structure calculation ionization dissociation

ionization Equilibrium and NLTE Effects on Compact Circumstellar HII Regions

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Science China Mathematics 1994年第7期37卷 850-861页

作者：蒋栋荣侯金良傅承启 Shanghai Observatory Academia Sinica Shanghai 200030 PRC

This paper presents the results of an extensive set of calculations about ionization equilibrium and NLTE effects on compact circumstellar HII regions embedded in clouds. In the mode! of a spherically symmetric and isothermal wind with a steady mass loss, pure hydrogen composition as well as Sobolev approximation, our research indicates that compact HII regions are far away from LTE state. The collisional ionization and photoionization from excited levels have great effects on the size of an HII region, the distribution of departure coefficients and the flux ratio of observed spectral lines. They can be used to explain the infrared line excess and the line deficit problems of YSOs. We conclude that it is unreasonable to infer the spectral type, mass loss rate and foreground extinction of the central star from optically thin line recombination theory.

关键词： compact HII region NLTE ionization equilibrium line excess and line deficit.

Excitation and ionization of OCS molecules in strong UV and NIR laser fields

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Chinese Physics B 2024年第7期33卷 285-291页

作者：师慧军刘洋孙添吕航徐海峰 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

Rydberg state excitation(RSE) is a highly non-linear physical phenomenon that is induced by the ionization of atoms or molecules in strong femtosecond laser fields. Here we observe that both parent and fragments(S, C, OC) of the triatomic molecule carbonyl sulfide(OCS) can survive strong 800 nm or 400 nm laser fields in high Rydberg states. The dependence of parent and fragment RSE yields on laser intensity and ellipticity is investigated in both laser fields, and the results are compared with those for strong-field ionization. Distinctly different tendencies for laser intensity and ellipticity are observed for fragment RSE compared with the corresponding ions. The mechanisms of RSE and strong-field ionization of OCS molecules in different laser fields are discussed based on the experimental results. Our study sheds some light on the strong-field excitation and ionization of molecules irradiated by femtosecond NIR and UV laser fields.

关键词： Rydberg state excitation strong field carbonyl sulfide ionization

Trajectory analysis of few-cycle strong field ionization in two-color circularly polarized fields

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Chinese Physics B 2019年第9期28卷 16-21页

作者： Yan Huang Chaochao Qin Yizhu Zhang Xincheng Wang Tian-Min Yan Yuhai Jiang College of Physics and Materials Science Henan Normal UniversityXinxiang 453007China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China University of Chinese Academy of Sciences Beijing 100049China ShanghaiTech University Shanghai 201210China Key Laboratory of Opto-electronics Information and Technical Science Tianjin UniversityTianjin 300072China

Bichromatic circularly polarized fields provide a useful tool to probe the ionization *** this work, we compare the photoelectron momentum distribution in few-cycle bichromatic field of different *** spectral features are analyzed with semiclassical trajectories derived from the strong field *** particular, the interference fringes in momentum distribution are investigated by tracking the ionization time and tunneling exits of released *** types of trajectories that contribute to the interference fringes are elucidated.

关键词： strong field ionization semiclassical trajectories bicircularly polarized fields photoelectron momentum

Abnormal ionization in sonoluminescence

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Chinese Physics B 2015年第4期24卷 456-462页

作者：张文娟安宇 Department of Physics Tsinghua University High School Affiliated to Shanghai Jiao Tong University (Jia Ding Campus)

Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%-70% as the bubble flashes, which is difficult to explain by using previous models.

关键词： sonoluminescence ionization ionized gas

Angle-resolved spectra of the direct above-threshold ionization of diatomic molecule in IR + XUV laser fields

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Chinese Physics B 2019年第2期28卷 185-191页

作者： Shang Shi Fa-Cheng Jin Bing-Bing Wang Laboratory of Optical Physics Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences Faculty of Science Xi'an Aeronautical University

The direct above-threshold ionization(ATI) of diatomic molecules in linearly-polarized infrared and extreme ultraviolet(IR+XUV) laser fields is investigated by the frequency–domain theory based on the nonperturbative quantum electrodynamics. The destructive interference fringes on the angle-resolved ATI spectra, which are closely related to the molecular structure, can be well fitted by a simple predictive formula for any alignment of the molecular axis. By comparing the direct ATI spectra for monochromatic and two-color laser fields, we found that the XUV laser field can both raise the ionization probability and the kinetic energy of the ionized electron, while the infrared(IR) laser field can broaden the energy distribution of the ionized electron. Our results demonstrate that, by using IR+XUV two-color laser fields, the angle-resolved spectra of the direct ATI can image the structural information of molecules without considering the recollision process of the ionized electron.

关键词： above-threshold ionization IR+XUV laser fields molecular structure