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Ultrafast Structural Changes in Chiral Molecules Measured with Free-Electron Lasers
2020, Schmidt, P., Music, V., Hartmann, G., Boll, R., Erk, B., Bari, S., Allum, F., Baumann, T.M., Brenner, G., Brouard, M., Burt, M., Coffee, R., Dörner, S., Galler, A., Grychtol, P., Heathcote, D., Inhester, L., Kazemi, M., Larsson, M., Li, Z., Lutmann, A., Manschwetus, B., Marder, L., Mason, R., Moeller, S., Osipov, T., Otto, H., Passow, C., Rolles, D., Rupprecht, P., Schubert, K., Schwob, L., Thomas, R., Vallance, C., Von Korff Schmising, C., Wagner, R., Walter, P., Wolf, T.J.A., Zhaunerchyk, V., Meyer, M., Ehresmann, A., Knie, A., Demekhin, P.V., Ilchen, M.
(X-ray) free-electron lasers are employed to site specifically interrogate atomic fragments during ultra-fast photolysis of chiral molecules via time-resolved photoelectron circular dichroism. © 2020 Institute of Physics Publishing. All rights reserved.
Photon-electron coincidence experiments at synchrotron radiation facilities with arbitrary bunch modes
2021, Ozga, C., Honisch, C., Schmidt, P., Holzapfel, X., Zindel, C., Küstner-Wetekam, C., Richter, C., Hergenhahn, U., Ehresmann, A., Knie, A., Hans, A.
We report the adaptation of an electron–photon coincidence detection scheme to the multibunch hybrid mode of the synchrotron radiation source BESSY II (Helmholtz-Zentrum Berlin). Single-event-based data acquisition and evaluation, combined with the use of relative detection times between the coincident particles, enable the acquisition of proper coincidence signals from a quasi-continuous excitation pattern. The background signal produced by accidental coincidences in the time difference representation is modeled using the non-coincident electron and photon spectra. We validate the method by reproducing previously published results, which were obtained in the single bunch mode, and illustrate its usability for the multibunch hybrid mode by investigating the photoionization of CO2 into CO+2 B satellite states, followed by subsequent photon emission. The radiative lifetime obtained and the electron binding energy are in good agreement with earlier publications. We expect this method to be a useful tool to extend the versatility of coincident particle detection to arbitrary operation modes of synchrotron radiation facilities and other excitation sources without the need for additional experimental adjustments.