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Hanle Effect for Lifetime Determinations in the Soft X-Ray Regime
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Orientador(es)
Resumo(s)
By exciting a series of 1s2 S01→1snpP11 transitions in heliumlike nitrogen ions with linearly polarized monochromatic soft x rays at the Elettra facility, we found a change in the angular distribution of the fluorescence sensitive to the principal quantum number n. In particular it is observed that the ratio of emission in directions parallel and perpendicular to the polarization of incident radiation increases with higher n. We find this n dependence to be a manifestation of the Hanle effect, which served as a practical tool for lifetime determinations of optical transitions since its discovery in 1924. In contrast to traditional Hanle effect experiments, in which one varies the magnetic field and considers a particular excited state, we demonstrate a "soft x-ray Hanle effect"which arises in a static magnetic field but for a series of excited states. By comparing experimental data with theoretical predictions, we were able to determine lifetimes ranging from hundreds of femtoseconds to tens of picoseconds of the 1snpP11 levels, which find excellent agreement with atomic-structure calculations. We argue that dedicated soft x-ray measurements could yield lifetime data that are beyond current experimental reach and cannot yet be predicted with sufficient accuracy.
Descrição
Grant No. UID/FIS/04559/2020 (LIBPhys).
Financial support was provided by the Max-Planck-Gesellschaft (MPG), Bundesministerium for Bildung und Forschung (BMBF) through project 05K13SJ2
C.S. acknowledges support from MPG and NASA-JHU Cooperative Agreement.
We acknowledge Elettra Sincrotrone Trieste for providing access to its synchrotron radiation facilities (long term proposals No. 20205206). Fabio Zuccaro is acknowledged for technical support during beamtime preparation and realization. J.R. and A.S. acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy-EXC-2123 QuantumFrontiers-390837967.
Publisher Copyright:
© 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society.
Palavras-chave
General Physics and Astronomy