Mainz 2017 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
Q: Fachverband Quantenoptik und Photonik
Q 54: Ultracold atoms and BEC - V (with A)
Q 54.3: Vortrag
Freitag, 10. März 2017, 11:30–11:45, N 1
Ultracold electron source from a MOT studied by ToF-microscopy — •Olena Fedchenko1, Sergey Chernov1, Melissa Vielle-Grosjean2, Gerd Schönhense1, and Daniel Comparat2 — 1Institut für Physik, JGU Mainz, Germany — 2University Paris-Sud, Orsay, France
We report on the first results of the application of cold Cs atoms as a monochromatic (photo-) electron source obtained with time-of-flight momentum microscopy. Such sources provide an electron beam for high energy resolution (meV-range) spectroscopic electron microscopy [1]. The experimental set-up consists of a magneto-optical trap with Cs atoms, ionization lasers, lens system of the ToF-microscope and delay-line detector [2]. Last two allow mapping of 3D spectral function I(kx, ky, t). The ToF study of photoelectron dynamics was performed using pulsed pico- and femtosecond lasers for ionization above or just at the ionization threshold. In the first case a picosecond pulsed LD @ 375 nm was used for the direct ionization from 6p3/2. In the second case a LD @ 1470 nm (excitation 6p3/2→7s1/2) was used in combination with a Ti-sapphire laser @ 750-800 nm (ionization from the 7s1/2). Consequently, varying the initial photoelectron energy in the range from 5 meV up to 860 meV above the ionization limit gives the opportunity to find optimal conditions to get the best electron beam parameters - time and energy spread, emittance, brightness and focusing.
Funded by ANR/DFG HREELM
[1] M. Kitajima et al., Europ. Phys. J. D 66, 130 (2012). [2] A. Oelsner et al., J. Electron Spectrosc. 178-179, 317 (2010).