Berlin 2001 – wissenschaftliches Programm
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Q: Quantenoptik
Q 32: Poster: Laser Spectroscopy
Q 32.4: Poster
Freitag, 6. April 2001, 12:30–15:00, AT2
High Resolution Spectroscopy of Atomic Hydrogen — •Marc Fischer1, Markus Niering1, Martin Weitz1,2, and Theodor W. Hänsch1,2 — 1Max-Planck-Institut für Quantenoptik, Garching, Germany — 2Ludwig-Maximilians-Universität München, Germany
Spectroscopy of the simple hydrogen atom allows for critical comparisons of theory and experiment. In particular, the hydrogen 1S-2S two-photon transition with its natural linewidth of 1.3 Hz is an intriguing object for determinations of fundamental constants, tests of QED, and furthermore is a candidate for a new optical frequency standard.
In our experiment, we investigate this transition by means of Doppler-free two-photon spectroscopy on a cold atomic beam, which is emitted collinearly to a standing laser wave near 243 nm. We use a time resolved measurement technique to select slow atoms from the thermal atomic beam. The frequency of the 1S-2S transition was determined to 1.8 parts in 1014[1]. We discuss systematic effects, as the second order Doppler shift and the ac Stark shift.
We give an overview of our experimental scheme and current work focusing on an improvement of the laser stability and the realization of a vacuum system with differential pumping. The latter should yield a reduced number of background gas particles and is expected to allow for spectroscopy of slower atoms.
[1] M. Niering et al., Phys. Rev. Lett. 84, 5496 (2000)