中国物理B ›› 2026, Vol. 35 ›› Issue (4): 43202-043202.doi: 10.1088/1674-1056/ae311d

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Comparing distinct dissociation pathways of C2H22+ under laser and electron impact

Xiangjie Chen(陈祥杰)1, Jianting Lei(雷建廷)1,2,†, Chenyu Tao(陶琛玉)2, Shuncheng Yan(闫顺成)2, Yongzhe Ma(马永哲)1, Fenghao Sun(孙烽豪)1, Qincao Liu(刘情操)1,‡, and Shaofeng Zhang(张少锋)2,3,4,§   

  1. 1 College of Science, Harbin Institute of Technology, Weihai 264209, China;
    2 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;
    3 University of Chinese Academy of Sciences, Beijing 100049, China;
    4 State Key Laboratory of Heavy Ion Science and Technology, Lanzhou 730000, China
  • 收稿日期:2025-10-23 修回日期:2025-12-21 接受日期:2025-12-25 出版日期:2026-03-24 发布日期:2026-03-24
  • 基金资助:
    This work was supported by the National Natural Science Foundation of China (Grant Nos. 12304376, 12504397, and 12204132), the Shandong Provincial Natural Science Foundation (Grant Nos. ZR2025QC1459, ZR2025QC1458, tsqn202408113, and ZR2023QA075), and the National Key Research and Development Program of China (Grant No. 2022YFA1602500).

Comparing distinct dissociation pathways of C2H22+ under laser and electron impact

Xiangjie Chen(陈祥杰)1, Jianting Lei(雷建廷)1,2,†, Chenyu Tao(陶琛玉)2, Shuncheng Yan(闫顺成)2, Yongzhe Ma(马永哲)1, Fenghao Sun(孙烽豪)1, Qincao Liu(刘情操)1,‡, and Shaofeng Zhang(张少锋)2,3,4,§   

  1. 1 College of Science, Harbin Institute of Technology, Weihai 264209, China;
    2 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;
    3 University of Chinese Academy of Sciences, Beijing 100049, China;
    4 State Key Laboratory of Heavy Ion Science and Technology, Lanzhou 730000, China
  • Received:2025-10-23 Revised:2025-12-21 Accepted:2025-12-25 Online:2026-03-24 Published:2026-03-24
  • Contact: Jianting Lei, Qincao Liu, Shaofeng Zhang E-mail:leijianting@hit.edu.cn;qingcao.liu@hit.edu.cn;zhangshf@impcas.ac.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (Grant Nos. 12304376, 12504397, and 12204132), the Shandong Provincial Natural Science Foundation (Grant Nos. ZR2025QC1459, ZR2025QC1458, tsqn202408113, and ZR2023QA075), and the National Key Research and Development Program of China (Grant No. 2022YFA1602500).

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摘要： We report a comparative study of the dissociation dynamics of ethyne (C$_{2}$H$_{2}$) molecules and clusters under a strong laser field ($9\times 10^{13}$ W/cm$^{2}$) and 1 keV electron impact. Using coincidence momentum imaging, we identify several two-body dissociation channels of C$_{2}$H$_{2}^{2+}$, including C$_{2}$H$^{+} + {\rm H}^{+}$, CH$_{2}^{+} + {\rm C}^{+}$, symmetric breakup into CH$^{+}$ + CH$^{+}$, as well as dimer dissociation channels such as C$_{2}$H$_{2}^{+} + {\rm C}_{2}$H$_{2}^{+}$ and C$_{2}$H$_{2}^{2+} + {\rm C}_{2}$H$_{2}^{+}$. By analyzing the kinetic energy release (KER) and branching ratios of the dominant fragmentation pathways, we demonstrate that double ionization under a strong laser field preferentially leads to dissociation on the singlet ground-state surface ($^{1}\Delta_{\rm g}$), whereas electron impact favors the triplet ground state ($^{3}\Sigma_{\rm g}^{-}$). This contrast is attributed to different ionization mechanisms: electron impact follows a propensity rule favoring the lower-energy triplet, while strong-field ionization aligned with the $\pi$ orbitals promotes singlet formation due to the Pauli exclusion principle. Our findings provide clear evidence of excitation-condition-dependent dissociation pathways in acetylene dications.

关键词: coincidence measurement, kinetic energy release (KER), Coulomb explosion, dissociation dynamics

Abstract: We report a comparative study of the dissociation dynamics of ethyne (C$_{2}$H$_{2}$) molecules and clusters under a strong laser field ($9\times 10^{13}$ W/cm$^{2}$) and 1 keV electron impact. Using coincidence momentum imaging, we identify several two-body dissociation channels of C$_{2}$H$_{2}^{2+}$, including C$_{2}$H$^{+} + {\rm H}^{+}$, CH$_{2}^{+} + {\rm C}^{+}$, symmetric breakup into CH$^{+}$ + CH$^{+}$, as well as dimer dissociation channels such as C$_{2}$H$_{2}^{+} + {\rm C}_{2}$H$_{2}^{+}$ and C$_{2}$H$_{2}^{2+} + {\rm C}_{2}$H$_{2}^{+}$. By analyzing the kinetic energy release (KER) and branching ratios of the dominant fragmentation pathways, we demonstrate that double ionization under a strong laser field preferentially leads to dissociation on the singlet ground-state surface ($^{1}\Delta_{\rm g}$), whereas electron impact favors the triplet ground state ($^{3}\Sigma_{\rm g}^{-}$). This contrast is attributed to different ionization mechanisms: electron impact follows a propensity rule favoring the lower-energy triplet, while strong-field ionization aligned with the $\pi$ orbitals promotes singlet formation due to the Pauli exclusion principle. Our findings provide clear evidence of excitation-condition-dependent dissociation pathways in acetylene dications.

Key words: coincidence measurement, kinetic energy release (KER), Coulomb explosion, dissociation dynamics

中图分类号:  (Photoionization and excitation)

  • 32.80.-t
32.10.-f (Properties of atoms) 32.80.Rm (Multiphoton ionization and excitation to highly excited states) 33.80.-b (Photon interactions with molecules)