中国物理B ›› 2006, Vol. 15 ›› Issue (7): 1511-1516.doi: 10.1088/1009-1963/15/7/022

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Cluster-assisted generation of multi-charged ions in nanosecond laser ionization of pulsed hydrogen sulfide beam at 1064 and 532nm

李海洋1, 罗晓琳1, 梁峰1, 李安林1, 牛冬梅2, 程爽2   

  1. (1)Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; (2)Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China；Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences,Hefei 230031, China
  • 收稿日期:2005-12-27 修回日期:2006-04-08 出版日期:2006-07-20 发布日期:2006-07-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 20573111) and partly supported by the Center for Computational Science, Hefei Institutes of Physical Sciences, China (Grant No 0331405002).

Cluster-assisted generation of multi-charged ions in nanosecond laser ionization of pulsed hydrogen sulfide beam at 1064 and 532nm

Niu Dong-Mei (牛冬梅)ab, Li Hai-Yang (李海洋)a, Luo Xiao-Lin (罗晓琳)a, Liang Feng (梁峰)a, Cheng Shuang (程爽)ab, Li An-Lin (李安林)a   

  1. a Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; b Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences,Hefei 230031, China
  • Received:2005-12-27 Revised:2006-04-08 Online:2006-07-20 Published:2006-07-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 20573111) and partly supported by the Center for Computational Science, Hefei Institutes of Physical Sciences, China (Grant No 0331405002).

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摘要： The multi-charged sulfur ions of Sq= (q\le 6) have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532,nm with an intensity of 1010\sim 1012W1\cdotcm-2. S6+ is the dominant multi-charged species at 1064nm, while S4+, S3+ and S2+ ions are the main multi-charged species at 532nm. A three-step model (i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing) is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to \lambda 2, \lambda being the laser wavelength.

关键词: cluster, multi-charged ion, inverse bremsstrahlung absorption, electron impact ionization

Abstract: The multi-charged sulfur ions of Sq+ ($q\leq 6$) have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532,nm with an intensity of 1010 $\sim$1012W1$\cdot$cm-2. S6+ is the dominant multi-charged species at 1064nm, while S4+, S3+ and S2+ ions are the main multi-charged species at 532nm. A three-step model (i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing) is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to $\lambda^2$, $\lambda$ being the laser wavelength.

Key words: cluster, multi-charged ion, inverse bremsstrahlung absorption, electron impact ionization

中图分类号:  (Charged clusters)

  • 36.40.Wa
33.15.Ta (Mass spectra) 33.80.Rv (Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states)) 34.80.Gs (Molecular excitation and ionization)