M Vedel

HIGHER ORDER NON-LINEAR RESONANCES IN A PAUL TRAP

Abstract We report some detailed investigations on non-linear resonances of high order as they appear in a radio-frequency ion trap, whose potential deviates from the ideal quadrupolar shape. The strength and shape of these resonances have been measured throughout the first stable region of the trap. Moreover, space charge shifts and also effects of a modulation of the trapping voltage on the shape of the resonances have been observed. Some of the resonances cannot be explained by the general rule that the sums of multiples of the ion macrofrequencies n r ω r + n z ω z ( n r , n z are integers) are multiples of the trapping field frequency Ω.

New Schemes for resonant ejection in r.f. quadrupolar ion traps

In order to achieve relative ion number measurement with the best possible accuracy, a systematic investigation of ion detection by resonance ejection has been performed. The first experiment is described here. Ions stored in a radiofrequency quadrupole trap were subjected, for a short time, to a sinusoidal voltage of small amplitude, the frequency of which was variable from zero to half of the r.f. drive frequency. This pulse, of duration 10 ms, was applied to the trap electrodes in either the dipolar or quadrupolar mode. The signal formed by ions ejected out of the trap was observed at two different times which permitted differentiation of ion ejection along the z direction from combined ion ejection along the x, y and z directions. As the frequency composition of the pulse is swept through the above range, the observed ion signals show absorptions at secular frequencies ωx, ωz, doubled frequencies, and combinations of ωx and ωz. These lines show anharmonicities and space charge perturbation. The second experiment attempts to analyze the effect of an initial pulse (or tickle) of a fixed frequency with a second pulse, the frequency of which is variable as described above, in order to explore the spectrum of ion motion under the influence of this tickle.

Evaluation of the ultimate performances of a Ca+ single-ion frequency standard

We numerically evaluate the expected performances of an optical frequency standard at 729 nm based on a single calcium ion. The frequency stability is studied through the Allan deviation and its dependence on the excitation method (single Rabi pulse or two Ramsey pulses schemes) and the laser linewidth are discussed. The minimum Allan deviation that can be expected is estimated to

Resonance excitation of ions stored in a quadrupole ion trap Part III. Introduction to the field interpolation simulation method

\sigma_y(\tau) \approx 2.5\times 10^{-15}/\sqrt{\tau}

High power broad-area diode laser at 794 nm injected by an external cavity laser

with

Metastable level lifetimes from electron-shelving measurements with ion clouds and single ions

\tau

A time-of-flight method for studying the properties of an ion cloud stored in an rf trap

the integration time. The frequency shifts induced by the environmental conditions are evaluated to minimize the uncertainty of the proposed standard by chosing the most suited environment for the ion. If using the odd isotope

Study of the SF6− ion lifetime in a rf quadrupole trap

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A sensitive method for the detection of stored ions by resonant ejection using a wide-band signal

Ca

Investigations on the Kinetic Energy of Trapped Ions by Consideration of Ion/Molecule Collisions

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