中国物理B ›› 2019, Vol. 28 ›› Issue (1): 13201-013201.doi: 10.1088/1674-1056/28/1/013201

• SPECIAL TOPIC—Recent advances in thermoelectric materials and devices • 上一篇    下一篇

Validity of extracting photoionization time delay from the first moment of streaking spectrogram

Chang-Li Wei(魏长立), Xi Zhao(赵曦)   

  1. 1 School of Physics and Electronics, Qiannan Normal College for Nationalities, Duyun 558000, China;
    2 Department of Physics, Kansas State University, Manhattan, KS 66506, USA
  • 收稿日期:2018-09-12 修回日期:2018-10-26 出版日期:2019-01-05 发布日期:2019-01-05
  • 通讯作者: Xi Zhao E-mail:zhaoxi719@ksu.edu
  • 基金资助:

    Project supported by the Talent Introduction Foundation of Qiannan Normal University of Nationalities, China (Grant No. qnsyrc201619), Natural Science Foundation of Guizhou Provincial Education Department for Young Talents, China (Grant No. Qian Education Contract KY[2017]339), and Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (Grant No. DE-FG02-86ER13491).

Validity of extracting photoionization time delay from the first moment of streaking spectrogram

Chang-Li Wei(魏长立)1, Xi Zhao(赵曦)2   

  1. 1 School of Physics and Electronics, Qiannan Normal College for Nationalities, Duyun 558000, China;
    2 Department of Physics, Kansas State University, Manhattan, KS 66506, USA
  • Received:2018-09-12 Revised:2018-10-26 Online:2019-01-05 Published:2019-01-05
  • Contact: Xi Zhao E-mail:zhaoxi719@ksu.edu
  • Supported by:

    Project supported by the Talent Introduction Foundation of Qiannan Normal University of Nationalities, China (Grant No. qnsyrc201619), Natural Science Foundation of Guizhou Provincial Education Department for Young Talents, China (Grant No. Qian Education Contract KY[2017]339), and Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (Grant No. DE-FG02-86ER13491).

摘要:

Photoionization time delays have been studied in many streaking experiments in which an attosecond pulse is used to ionize the atomic or solid state target in the presence of a dressing infrared laser field. Among the methods of extracting the time delay from the streaking spectrogram, the simplest one is to calculate the first moment of the spectrogram and to measure its offset relative to the vector potential of the infrared field. The first moment method has been used in many theoretical simulations and analysis of experimental data, but the meaning of this offset needs to be investigated. We simulate the spectrograms and compare the extracted time delay from the first moment with the input Wigner delay. In this study, we show that the first moment method is valid only when the group delay dispersions corresponding to both the spectral phase of the attosecond pulse and the phase of the single-photon transition dipole matrix element of the target are small. Under such circumstance, the electron wave packet behaves like a classical particle and the extracted time delay can be related to a group delay in the photoionization process. To avoid ambiguity and confusion, we also suggest that the photoionization time delay be replaced by photoionization group delay and the Wigner time delay be replaced by Wigner group delay.

关键词: photoionization time delay, strong laser field, attosecond science, first moment

Abstract:

Photoionization time delays have been studied in many streaking experiments in which an attosecond pulse is used to ionize the atomic or solid state target in the presence of a dressing infrared laser field. Among the methods of extracting the time delay from the streaking spectrogram, the simplest one is to calculate the first moment of the spectrogram and to measure its offset relative to the vector potential of the infrared field. The first moment method has been used in many theoretical simulations and analysis of experimental data, but the meaning of this offset needs to be investigated. We simulate the spectrograms and compare the extracted time delay from the first moment with the input Wigner delay. In this study, we show that the first moment method is valid only when the group delay dispersions corresponding to both the spectral phase of the attosecond pulse and the phase of the single-photon transition dipole matrix element of the target are small. Under such circumstance, the electron wave packet behaves like a classical particle and the extracted time delay can be related to a group delay in the photoionization process. To avoid ambiguity and confusion, we also suggest that the photoionization time delay be replaced by photoionization group delay and the Wigner time delay be replaced by Wigner group delay.

Key words: photoionization time delay, strong laser field, attosecond science, first moment

中图分类号:  (Multiphoton ionization and excitation to highly excited states)

  • 32.80.Rm
42.50.Hz (Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift) 42.65.Ky (Frequency conversion; harmonic generation, including higher-order harmonic generation)