Prospects for laser spectroscopy of highly charged ions with high-harmonic XUV and soft x-ray sources. (26th November 2015)

• Record Type: Journal Article
• Authors: Rothhardt, J; Hädrich, S; Demmler, S; Krebs, M; Winters, D F A; Kühl, Th; Stöhlker, Th; Limpert, J; Tünnermann, A
• Is Part Of: Physica scripta. Volume T166(2015:Nov.)
• Publication Date: 2015-11-26
• Subjects: highly-charged ions -- laser spectroscopy -- XUV laser; Physics -- Periodicals; 530.05
• DOI: 10.1088/0031-8949/2015/T166/014030
• Languages: English
• ISSNs: 0031-8949

Abstract

Abstract: We present novel high photon flux XUV and soft x-ray sources based on high harmonic generation (HHG). The sources employ femtosecond fiber lasers, which can be operated at very high (MHz) repetition rate and average power (>100 W). HHG with such lasers results in ∼10 13 photons s −1 within a single harmonic line at ∼40 nm (∼30 eV) wavelength, a photon flux comparable to what is typically available at synchrotron beam lines. In addition, resonant enhancement of HHG can result in narrow-band harmonics with high spectral purity—well suited for precision spectroscopy. These novel light sources will enable seminal studies on electronic transitions in highly-charged ions. For example, at the experimental storage ring 2s1/2 –2p1/2 transitions in Li-like ions can be excited up to Z = 47 (∼100 eV transition energy), which provides unique sensitivity to quantum electro-dynamical effects and nuclear corrections. We estimate fluorescence count rates of the order of tens per second, which would enable studies on short-lived isotopes as well. In combination with the Doppler up-shift available in head-on excitation at future heavy-ion storage rings, such as the high energy storage ring, even multi-keV transitions can potentially be excited. Pump–probe experiments with femtosecond resolution could also be feasible and access the lifetime of short-lived excited states, thus providing novel benchmarks for atomic structure theory.