Precision Determination of Cyclotron Frequencies of Free Electrons and Ions

Abstract

Within the last two decades the electrodynamical storage of electrons and ions developed into an experimental method of great versatility. That this method is now being used in so many different fields of physics and chemistry results primarily from the long storage times which nowadays can be achieved. Under ultrahigh vacuum conditions and in sufficiently strong electromagnetic fields the particles can easily be trapped for hours or even days. This really long storage time offers the possibility of studying reactions of very slow rate to the chemist and of precision measurement of photon-ion interactions to the physicist. The accuracy of photon-ion interaction measurement is finally limited by Heisenberg’s uncertainty relation. Therefore long interaction times correspond to narrow line widths. An excellent example is the determination of the hyperfine structure of stored Barium ions [1] . The transition frequency is about 10 GHz, the absolute line width achieved in this experiment was a few Hz only. Therefore the fractional line width is of the order of one part in 10¹⁰ opening the introduction of this method as a future frequency or time standard. In an analogous fashion electrons were trapped to measure the anomalous part of their magnetic moment to one part in 10⁸ , now the best known elementary particle poperty at all [2]. Last not least atomic masses have been measured to high accuracy.