Precision Spectroscopy of Helium
Authors: Cancio P., Artoni M., Giusfredi G., Minardi F., Pavone FS., Inguscio M.
Autors Affiliation: Istituto Nazionale di Ottica Applicata (INOA)
Dip. di Fisica, Università di Firenze
Abstract: High-precision laser spectroscopy of helium is a powerful tool for testing QED calculations and for an accurate determination of the fine-structure constant α. Here, we report a new measurement of the fine-structure intervals of the 23P level of helium with an accuracy of kHz. They are measured from the frequency difference between 23P1→23Pj optical transitions observed with fluorescence-saturation spectroscopy in an atomic beam, in the absence of magnetic fields. A discussion of the systematic effects in the measurements is given, describing for the first time in helium the shift induced by mechanical effects of the light. Finally, a comparison with previously reported measurements is discussed.
KeyWords: Fine structure; He;