自由电子激光制备高强度亚稳态氦原子和类氦离子  

Free electron laser prepared high-intensity metastable helium and helium-like ions

作　　者：杜小娇 魏龙 孙羽 胡水明[2] Du Xiao-Jiao;Wei Long;Sun Yu;Hu Shui-Ming(Institute of Advanced Science Facilities,Shenzhen 518107,China;Department of Chemical Physics,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]深圳综合粒子设施研究院,深圳518107 [2]中国科学技术大学化学物理系,合肥230026

出　　处：《物理学报》2024年第15期22-29,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12304291,22241301,91736101,12393822);国家科技部博士后基金(批准号:2022M723062)资助的课题

摘　　要：在少电子原子精密光谱测量中,产生高强度、单一量子态的氦原子和类氦离子是实验研究的关键,也是改善实验测量信噪比的决定性因素.本文提出利用自由电子激光获得高强度亚稳态氦原子和类氦离子的实验方案.激光的制备效率可以通过求解光和原子相互作用的主方程获得,根据拟建设的深圳自由电子激光装置的设计参数和实验条件,计算得到亚稳态He,Li^(+)和Be^(2+)的制备效率分别可达3%,6%和2%以上.与常见的气体放电和电子轰击等制备方法相比,激光激发产生亚稳态原子/离子不仅可以提高制备产率,也可以降低放电时产生的电子、离子以及光子等高能杂散粒子的影响.利用自由电子激光激发制备亚稳态氦原子和类氦离子有望应用于多个研究领域.In the precision spectroscopy of few-electron atoms,the generation of high-intensity metastable helium atoms and helium-like ions is crucial for implementing experimental studies as well as a critical factor for improving the signal-to-noise ratio of experimental measurements.With the rapid development of free-electronlaser(FEL)and technology,FEL wavelengths extend from hard X-rays to soft X-rays and even vacuum ultraviolet bands.Meanwhile,laser pulses with ultra-fast,ultra-intense and high repetition frequencies are realized,thus making it possible for FEL to prepare single-quantum state atoms/ions with high efficiency.In this work,we propose an experimental method for obtaining high-intensity single-quantum state helium atoms and helium-like ions by using FEL.The preparation efficiency can be calculated by solving the master equation of light-atom interaction.Considering the experimental parameters involved in this work,we predict that the efficiencies of preparing metastable 2^(3)S He,Li^(+)and Be^(2+)are about 3%,6%and 2%,respectively.Compared with the common preparation methods such as gas discharge and electron bombardment,a state-of-the-art laser excitation method can not only increase the preparation efficiency,but also reduce the effects of high-energy stray particles such as electrons,ions,and photons generated during discharge.Furthermore,combined with the laser preparation technique,the sophisticated ion confinement technique,which can ensure a long interaction time between the ions and laser,increases the efficiency of metastableLi^(+)and Be^(2+)by several orders of magnitude.Therefore,the preparation of high-intensity metastable helium and helium-like ions can improve the measurement accuracy of precision spectroscopy of atoms and ions.A new experimental method,based on FEL,to study the fine structure energy levels 2^(3)P of helium,has the potential to obtain the results with an accuracy exceeding the sub-kHz level.Thus,the high-precision fine structure constants can be determined with the developme

关 键 词：亚稳态氦原子和类氦离子 精密光谱 自由电子激光 测量信噪比 制备效率 

分 类 号：O56[理学—原子与分子物理]