DATE2025.04.26 #Press Releases
Spectroscopic Measurement with Ultrahigh Resolution Using Intense Ultrashort-Pulsed Laser
-- Observation of Distortion in Electron Density Distribution in Atoms by Relativistic Effect --
Summary
A research group of Project Professor Kaoru Yamanouchi at the Institute for Attosecond Laser Facility, The University of Tokyo, and Project Associate Professor Toshiaki Ando, Assistant Professor Kana Yamada, and Professor Atsushi Iwasaki at School of Science has succeeded in measuring with high precision the isotope shift in the energy difference (fine structure splitting energy) between the 2P1/2 and 2P3/2 states of Krypton ions (Kr⁺) by introducing a long-arm interferometer into “Strong-Field Ultrahigh-Resolution Fourier Transform (SURF) Spectroscopy” technique and confirmed that the electron density distribution is distorted by the relativistic effect.
The isotope shift in the fine structure splitting energy of atoms is known to be an ideal system for observing the distortion of the electron density distribution induced by the relativistic effect. However, due to various limitations in experiments, such measurements had only been reported in Barium ions and Francium atoms around 40 years ago. If the precision of this SURF spectroscopy can be further improved, it is expected that isotope shift data may enable discussions beyond the Standard Model.
Figure: Isotope shift in Krypton ions (Kr⁺)
The slope of the fitted curve becomes negative because of the relativistic effect. (Reproduced from the original paper)
Publication details
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Journal Physical Review Research Paper Title Isotope shift of fine structure of Kr+ and hyperfine structure of 83Kr+ by strong-field ultrahigh-resolution Fourier-transform spectroscopyAuthors Toshiaki Ando, Kana Yamada, Atsushi Iwasaki, *Kaoru Yamanouchi (*Corresponding author) DOI 10.1103/PhysRevResearch.7.L022025