Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser Pulses
Photoionization dynamics of bounded electrons in the ground state, the first and second excited states of a hydrogen atom, triggered by ultrashort near-infrared laser pulses, have been investigated in a transition regime (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML&...
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MDPI AG
2022-04-01
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| Series: | Photonics |
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| Online Access: | https://www.mdpi.com/2304-6732/9/4/256 |
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| author | Peipei Xin Tianhui Qiu Hongyang Ma Hua Yuan Hongping Liu |
| author_facet | Peipei Xin Tianhui Qiu Hongyang Ma Hua Yuan Hongping Liu |
| author_sort | Peipei Xin |
| collection | DOAJ |
| description | Photoionization dynamics of bounded electrons in the ground state, the first and second excited states of a hydrogen atom, triggered by ultrashort near-infrared laser pulses, have been investigated in a transition regime (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>γ</mi><mo>∼</mo><mn>1</mn></mrow></semantics></math></inline-formula>) that offers both multiphoton and tunneling features. Significant differences in spectral characteristics are found between the three low-energy states. The H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>s</mi></mrow></semantics></math></inline-formula>) ionization probability is larger than the H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>p</mi></mrow></semantics></math></inline-formula>) value with a special oscillating structure, but both are much greater than the ground state H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mi>s</mi></mrow></semantics></math></inline-formula>) in a wide range of laser intensities. By comparing the momentum spectrum and angular distributions of low-energy photoelectrons released from these degenerate states, we find the H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>p</mi></mrow></semantics></math></inline-formula>) state shows a stronger long-range Coulomb attraction force than the H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>s</mi></mrow></semantics></math></inline-formula>) state on account of the difference in the initial electron wave packet. Furthermore, analysis of the photoelectron momentum distributions sheds light on both the first and second excited states with a symmetrical intercycle interference structure in a multicycle field but an intracycle interference of an asymmetric left-handed or right-handed rotating spectrum in a few-cycle field. By analyzing photoelectron spectroscopy, we identify the parity characteristics of photoelectrons in different energy intervals and their corresponding above-threshold single-photon ionization (ATSI) or above-threshold double-photon ionization (ATDI) processes. We finally present the momentum distributions of the electrons ionized by laser pulses with different profiles and find the carrier-envelope phase (CEP) is a strong factor in deciding the rotating structure of the emission spectrum, which provides a new method to distinguish the CEP of few-cycle pulses. |
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| spelling | doaj.art-6b95faa226134d5e8465100af3a1a3c42023-12-01T21:19:25ZengMDPI AGPhotonics2304-67322022-04-019425610.3390/photonics9040256Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser PulsesPeipei Xin0Tianhui Qiu1Hongyang Ma2Hua Yuan3Hongping Liu4School of Science, Qingdao University of Technology, Qingdao 266525, ChinaSchool of Science, Qingdao University of Technology, Qingdao 266525, ChinaSchool of Science, Qingdao University of Technology, Qingdao 266525, ChinaSchool of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255049, ChinaState Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, ChinaPhotoionization dynamics of bounded electrons in the ground state, the first and second excited states of a hydrogen atom, triggered by ultrashort near-infrared laser pulses, have been investigated in a transition regime (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>γ</mi><mo>∼</mo><mn>1</mn></mrow></semantics></math></inline-formula>) that offers both multiphoton and tunneling features. Significant differences in spectral characteristics are found between the three low-energy states. The H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>s</mi></mrow></semantics></math></inline-formula>) ionization probability is larger than the H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>p</mi></mrow></semantics></math></inline-formula>) value with a special oscillating structure, but both are much greater than the ground state H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mi>s</mi></mrow></semantics></math></inline-formula>) in a wide range of laser intensities. By comparing the momentum spectrum and angular distributions of low-energy photoelectrons released from these degenerate states, we find the H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>p</mi></mrow></semantics></math></inline-formula>) state shows a stronger long-range Coulomb attraction force than the H(<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>s</mi></mrow></semantics></math></inline-formula>) state on account of the difference in the initial electron wave packet. Furthermore, analysis of the photoelectron momentum distributions sheds light on both the first and second excited states with a symmetrical intercycle interference structure in a multicycle field but an intracycle interference of an asymmetric left-handed or right-handed rotating spectrum in a few-cycle field. By analyzing photoelectron spectroscopy, we identify the parity characteristics of photoelectrons in different energy intervals and their corresponding above-threshold single-photon ionization (ATSI) or above-threshold double-photon ionization (ATDI) processes. We finally present the momentum distributions of the electrons ionized by laser pulses with different profiles and find the carrier-envelope phase (CEP) is a strong factor in deciding the rotating structure of the emission spectrum, which provides a new method to distinguish the CEP of few-cycle pulses.https://www.mdpi.com/2304-6732/9/4/256degenerate statestunneling ionizationmultiphoton excitationstrong laser pulses |
| spellingShingle | Peipei Xin Tianhui Qiu Hongyang Ma Hua Yuan Hongping Liu Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser Pulses Photonics degenerate states tunneling ionization multiphoton excitation strong laser pulses |
| title | Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser Pulses |
| title_full | Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser Pulses |
| title_fullStr | Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser Pulses |
| title_full_unstemmed | Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser Pulses |
| title_short | Photoionization of Electrons in Degenerate Energy Level of Hydrogen Atom Induced by Strong Laser Pulses |
| title_sort | photoionization of electrons in degenerate energy level of hydrogen atom induced by strong laser pulses |
| topic | degenerate states tunneling ionization multiphoton excitation strong laser pulses |
| url | https://www.mdpi.com/2304-6732/9/4/256 |
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