Düsseldorf 2007 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 33: Poster Präzisionsmessungen
Q 33.8: Poster
Dienstag, 20. März 2007, 16:30–18:30, Poster C
Precision spectroscopy of trapped HD+ ions and the electron-to-proton mass ratio — •Jeroen Koelemeij, Bernhard Roth, Andreas Wicht, Ingo Ernsting, and Stephan Schiller — Institut für Experimentalphysik, Universität Düsseldorf
Recently, we successfully demonstrated infrared rovibrational spectroscopy of trapped and sympathetically cooled HD+ ions at millikelvin temperatures. The long (tens of minutes) storage time of HD+, together with the low translational temperature and near absence of background-gas collisions in our ultrahigh vacuum apparatus, provide excellent circumstances for precision spectroscopy. Being one of the simplest molecules, HD+ is also highly accessible to theory. As the rovibrational energy levels of HD+ depend on the electron-proton mass ratio me/mp, the calculated and measured energy differences between those levels can be combined to extract this fundamental mass ratio. Our latest experimental result agrees with the most accurate available ab initio theory to within the measurement accuracy (2 ppb), whereas the theoretical uncertainty is 0.2 ppb. This allows confirmation of the 2002 CODATA recommended value for me/mp to within 5 ppb. For comparison, the 2002 CODATA value itself has a relative accuracy of 0.46 ppb. Our experimental uncertainty is currently limited by substantial Doppler broadening of the observed spectra, even at the low translational temperatures achieved here. Therefore, a new ion trap is under construction, which should enable Doppler-free infrared spectroscopy in the Lamb-Dicke regime. This is expected to improve the spectroscopic accuracy by more than one order of magnitude.