Speaker
Dr
Michael Meyer
(European XFEL)
Description
The combination of intense femtosecond X-ray and NIR pulses produced by Free Electron Lasers (FEL) and synchronized optical lasers, respectively, offers various opportunities to gain detailed insight into atomic photoionization dynamics. After an early study on the linear dichroism in the two-color photoionization of helium at FLASH [1], we have now taken advantage of the availability of circularly polarized XUV radiation at FERMI to explore the circular dichroism and its influence on the photoionization dynamics [2]. The combined XUV and optical fields give rise to the formation of so-called sidebands in the photoelectron spectrum. The variation of the intensity of these sidebands, when switching the helicity of one of the light fields, is defined as circular dichroism in the photoionization and provides unique information on the partial photoionization cross sections, i.e. on the relative importance of the angular momentum of the outgoing electrons. In addition, the comparison of the experimental data with the results of theoretical models describing the two-color photoionization process eenables us to determine the degree of circular polarization of the FEL beam as well as the sign of the helicity, i.e. parameters, which are generally difficult to extract by other means. Possibilities for future applications, including resonant phenomena, will be outlined and discussed.
[1] M. Meyer et al., Phys. Rev. Lett. 101, 193002 (2008)
[2] T. Mazza et al . Nat.Comm. 5, 3648 (2014)
Primary author
Dr
Michael Meyer
(European XFEL)
Co-authors
Prof.
Alexei Grum-Grhzimailo
(Lomonosov Moscow State University)
Prof.
Andrej Kazansky
(Donostia International Physics Center)
Dr
Carlo Callegari
(Elettra)
Dr
Elena Gryzlova
(Lomonosov Moscow State University)
Prof.
John Costello
(Dublin City University)
Dr
Kevin Prince
(Elettra)
Prof.
Kiyoshi Ueda
(Tohoku University)
Prof.
Lorenzo Avaldi
(CNR IMIP)
Dr
Marcello Coreno
(Elettra)
Dr
Markus Ilchen
(European XFEL)
Prof.
Nikolay Kabachnik
(European XFEL)
Dr
Oksana Plekan
(Elettra)
Dr
Paola Bolognesi
(CNR IMIP)
Dr
Paola Finetti
(Elettra)
Dr
Patrick O'Keeffe
(CNR IMIP)
Dr
Robert Richter
(Elettra)
Dr
Tommaso Mazza
(European XFEL)
