Description
Precision experiments in the hydrogen atom have a long tradition and extensive studies of transitions between low lying $n\leq12$ states were carried out [1-6]. These measurements can be used to determine values of the Rydberg constant and the proton charge radius. We present a new experimental approach to perform measurements of transition frequencies between the metastable 2s $^{2}$S$_{1/2} (F = 0,1)$ state of H and highly excited $n$p-Rydberg states with principal quantum number $n \geq 23$.
We generate the hydrogen atoms by dissociating H$_2$ in a dielectric barrier discharge located at the orifice of a pulsed cryogenic valve. The hydrogen atoms are entrained in the supersonic expansion of H$_2$. The atoms are photoexcited to a specific hyperfine level of the metastable 2s $^{2}$S$_{1/2}$ state by a home-built frequency-tripled Fourier-transform-limited pulsed titanium-sapphire laser (pulse length 40 ns). They enter a magnetically shielded region in which transitions to $n$p Rydberg states are induced by a narrow-band frequency-doubled continuous-wave titanium-sapphire laser, which is phase locked to an optically stabilized frequency comb and referenced over a fiber network to a SI traceable primary frequency standard [7]. The highly excited Rydberg states are detected by pulsed-field ionization. We will report progress on our efforts to minimize uncertainties from stray electric fields and Doppler shifts and to obtain spectral lines with a FWHM below 10 MHz.
This work was supported by the Swiss National Science Foundation through the Sinergia-Program (Grant No. CRSII5-183579) and Grant No. 200020B-200478.
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| Presenter name | Simon Scheidegger |
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