Scientific Results – CNR – Istituto Nazionale di Ottica

Precision Spectroscopy of Helium

Year: 1999

Authors: Cancio P., Artoni M., Giusfredi G., Minardi F., Pavone FS., Inguscio M.

Autors Affiliation: Istituto Nazionale di Ottica Applicata (INOA)
Dip. di Fisica, Universit� 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→2³P_j 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.

Journal/Review: JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS

KeyWords: Fine structure; He;