0000000000282056
AUTHOR
R. Alheit
Hyperfine-structure measurements on trapped Pb II.
The 6${\mathit{P}}_{3/2}$-6${\mathit{P}}_{1/2}$ magnetic dipole resonance transition in ${\mathrm{Pb}}^{+}$ has been observed by cw laser excitation of an ion cloud stored in a Paul trap and subsequent detection of the fluorescence radiation. From the hyperfine-structure splitting of the spectrum we determine the A factor for the ground state, A(${\mathit{P}}_{1/2}$)=12.967(13) GHz, and the excited state, A(${\mathit{P}}_{3/2}$)=0.580(3) GHz. From a contamination of $^{208}\mathrm{Pb}$ in our sample we derived the $^{207}\mathrm{Pb}^{+}$${\mathrm{\ensuremath{-}}}^{208}$${\mathrm{Pb}}^{+}$ isotope shift [\ensuremath{\Delta}\ensuremath{\nu}=311(14) MHz]. A small electric quadrupole admixture …
Vibrational population of H 2 + after electroionization of thermal H2
In an ion trap experiment we have determined the vibrational population of the lowest 9 vibrational levels of H2+. We used photodissociation of the trapped molecules by 248 nm light from an excimer laser and the dependence of the photodissociation cross section from the vibrational state. Our results are in good agreement to calculations, which are based on the Franck-Condon principle, but include a variation of the internuclear distance in the transition matrix element.
Fractional frequency collective parametric resonances of an ion cloud in a Paul trap
ion cloud ina Paul trap driven at simple fractions of twice the secular frequency of the trap by an additionally appliedquadrupole field. The fractional resonances are observable only if the excitation field surpasses a criticalstrength. Odd-even staggering of the thresholds is observed.@S1050-2947~98!51307-8#PACS number~s!: 32.80.Pj, 07.75.1h
Nonlinear collective oscillations of an ion cloud in a Paul trap
In an experiment using a Paul trap, we create a ${\mathrm{H}}_{2}^{+}$ ion cloud by electron ionization of the background gas at ${10}^{\ensuremath{-}9}$-mbar residual pressure. Exciting the ions parametrically at twice the frequency of the secular motion of ions in the $r$ or $z$ direction, we observe a narrow resonance at some distance from the motional resonance center if the amplitude of the exciting field exceeds a threshold value. The threshold value decreases with increasing ion number. Since the narrow resonance does not shift with ion number, we interpret it as a collective resonance of the center of mass of the ion cloud. The resonance shape exhibits the typical form of a driven a…
Observation of instabilities in a Paul trap with higher-order anharmonicities
Systematic measurements of the relative ion number stored in a Paul trap within the stability diagram given by the solution of the equation of motion reveal many lines, where only few or no ions can be confined. The observations can be explained by the presence of perturbations from higher-order components in the trapping potential, which is a quadrupole potential in the ideal case. The resonances follow the equation (nr/2)βr + (nr/2)βz = 1,nr +nz =N, where 2N is the order of the perturbation,nr,nz are integer andβr,βz are stability parameters of the trap. The experiments were performed on H+ and H2+ ions, which are detected after a storage time of 0.3 s by ejection from the trap.
Isotope separation by nonlinear resonances in a Paul trap
Deviations from the ideal quadrupole potential in a Paul ion trap create nonlinear resonances at certain operating points inside the stability diagram, where in the absence of potential pertubations storing times are very long. In the presence of those pertubations, however, the ions are lost from the trap. Since these resonances are mass dependent and the mass resolution is of the order of 100 it can be used to separate isotopes of a given element by choosing suitable trap operating conditions. Experiments on a natural mixture of Eu+ ions of mass 151 and 153 show that in a simple way, by proper choice of the operating point, the ions can be completely separated and laser-induced optical sp…