Low-Energy Protons in Strong-Field Dissociation of H_(2)^(+) via Dipole-Transitions at Large Bond Lengths  

作　　者：Shengzhe Pan Chenxi Hu Zhaohan Zhang Peifen Lu Chenxu Lu Lianrong Zhou Jiawei Wang Fenghao Sun Junjie Qiang Hui Li Hongcheng Ni Xiaochun Gong Feng He Jian Wu 

机构地区：[1]State Key Laboratory of Precision Spectroscopy,East China Normal University,Shanghai 200241,China [2]Key Laboratory for Laser Plasmas(Ministry of Education)and School of Physics and Astronomy,Collaborative Innovation Center of IFSA(CICIFSA),Shanghai Jiao Tong University,Shanghai 200240,China [3]CAS Center for Excellence in Ultra-Intense Laser Science,Shanghai 201800,China [4]Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan,Shanxi 030006,China

出　　处：《Ultrafast Science》2022年第2期9-17,共9页超快科学（英文）

基　　金：supported by the National Key R&D Program of China(Grant Nos.2018YFA0306303,2018YFA0404802);the National Natural Science Fund(Grant Nos.11834004,11621404,11925405,91850203);the 111 Project of China(Grant No.B12024);Projects from Shanghai Science and Technology Commission(Grant No.19JC1412200);the Innovation Program of Shanghai Municipal Education Commission(Grant No.2017-01-07-00-02-E00034);S.Pan acknowledges the support from the Academic Innovation Ability Enhancement Program for Excellent Doctoral Students of East China Normal University in 2021(Grant No.40600-30302-515100/141).

摘　　要：More than ten years ago,the observation of the low-energy structure in the photoelectron energy spectrum,regarded as an“ionization surprise,”has overthrown our understanding of strong-field physics.However,the similar low-energy nuclear fragment generation from dissociating molecules upon the photon energy absorption,one of the well-observed phenomena in light-molecule interaction,still lacks an unambiguous mechanism and remains mysterious.Here,we introduce a time-energy-resolved manner using a multicycle near-infrared femtosecond laser pulse to identify the physical origin of the light-induced ultrafast dynamics of molecules.By simultaneously measuring the bond-stretching times and photon numbers involved in the dissociation of H_(2)^(+) driven by a polarization-skewed laser pulse,we reveal that the low-energy protons(below 0.7 eV)are produced via dipole-transitions at large bond lengths.The observed low-energy protons originate from strong-field dissociation of high vibrational states rather than the low ones of H_(2)^(+) cation,which is distinct from the well-accepted bond-softening picture.Further numerical simulation of the time-dependent Schrödinger equation unveils that the electronic states are periodically distorted by the strong laser field,and the energy gap between the field-dressed transient electronic states may favor the one-or three-photon transitions at the internuclear distance larger than 5 a.u.The time-dependent scenario and our time-energy-resolved approach presented here can be extended to other molecules to understand the complex ultrafast dynamics.

关 键 词：dynamics TRANSITIONS DISSOCIATION 

分 类 号：O57[理学—粒子物理与原子核物理]